Skip to content

Most visited

Recently visited

navigation

RecyclerView.LayoutManager

public static abstract class RecyclerView.LayoutManager
extends Object

java.lang.Object
   ↳ android.support.v7.widget.RecyclerView.LayoutManager
Known Direct Subclasses
Known Indirect Subclasses


A LayoutManager is responsible for measuring and positioning item views within a RecyclerView as well as determining the policy for when to recycle item views that are no longer visible to the user. By changing the LayoutManager a RecyclerView can be used to implement a standard vertically scrolling list, a uniform grid, staggered grids, horizontally scrolling collections and more. Several stock layout managers are provided for general use.

If the LayoutManager specifies a default constructor or one with the signature (Context, AttributeSet, int, int), RecyclerView will instantiate and set the LayoutManager when being inflated. Most used properties can be then obtained from getProperties(Context, AttributeSet, int, int). In case a LayoutManager specifies both constructors, the non-default constructor will take precedence.

Summary

Nested classes

interface RecyclerView.LayoutManager.LayoutPrefetchRegistry

Interface for LayoutManagers to request items to be prefetched, based on position, with specified distance from viewport, which indicates priority. 

class RecyclerView.LayoutManager.Properties

Some general properties that a LayoutManager may want to use. 

XML attributes

android.support.v7.recyclerview:reverseLayout  
android.support.v7.recyclerview:spanCount  
android.support.v7.recyclerview:stackFromEnd  
android:orientation  

Public constructors

RecyclerView.LayoutManager()

Public methods

void addDisappearingView(View child, int index)

To be called only during onLayoutChildren(Recycler, State) to add a view to the layout that is known to be going away, either because it has been removed or because it is actually not in the visible portion of the container but is being laid out in order to inform RecyclerView in how to animate the item out of view.

void addDisappearingView(View child)

To be called only during onLayoutChildren(Recycler, State) to add a view to the layout that is known to be going away, either because it has been removed or because it is actually not in the visible portion of the container but is being laid out in order to inform RecyclerView in how to animate the item out of view.

void addView(View child, int index)

Add a view to the currently attached RecyclerView if needed.

void addView(View child)

Add a view to the currently attached RecyclerView if needed.

void assertInLayoutOrScroll(String message)

Checks if RecyclerView is in the middle of a layout or scroll and throws an IllegalStateException if it is not.

void assertNotInLayoutOrScroll(String message)

Checks if RecyclerView is in the middle of a layout or scroll and throws an IllegalStateException if it is.

void attachView(View child)

Reattach a previously detached view.

void attachView(View child, int index)

Reattach a previously detached view.

void attachView(View child, int index, RecyclerView.LayoutParams lp)

Reattach a previously detached view.

void calculateItemDecorationsForChild(View child, Rect outRect)

Calculates the item decor insets applied to the given child and updates the provided Rect instance with the inset values.

boolean canScrollHorizontally()

Query if horizontal scrolling is currently supported.

boolean canScrollVertically()

Query if vertical scrolling is currently supported.

boolean checkLayoutParams(RecyclerView.LayoutParams lp)

Determines the validity of the supplied LayoutParams object.

static int chooseSize(int spec, int desired, int min)

Chooses a size from the given specs and parameters that is closest to the desired size and also complies with the spec.

void collectAdjacentPrefetchPositions(int dx, int dy, RecyclerView.State state, RecyclerView.LayoutManager.LayoutPrefetchRegistry layoutPrefetchRegistry)

Gather all positions from the LayoutManager to be prefetched, given specified momentum.

void collectInitialPrefetchPositions(int adapterItemCount, RecyclerView.LayoutManager.LayoutPrefetchRegistry layoutPrefetchRegistry)

Gather all positions from the LayoutManager to be prefetched in preperation for its RecyclerView to come on screen, due to the movement of another, containing RecyclerView.

int computeHorizontalScrollExtent(RecyclerView.State state)

Override this method if you want to support scroll bars.

int computeHorizontalScrollOffset(RecyclerView.State state)

Override this method if you want to support scroll bars.

int computeHorizontalScrollRange(RecyclerView.State state)

Override this method if you want to support scroll bars.

int computeVerticalScrollExtent(RecyclerView.State state)

Override this method if you want to support scroll bars.

int computeVerticalScrollOffset(RecyclerView.State state)

Override this method if you want to support scroll bars.

int computeVerticalScrollRange(RecyclerView.State state)

Override this method if you want to support scroll bars.

void detachAndScrapAttachedViews(RecyclerView.Recycler recycler)

Temporarily detach and scrap all currently attached child views.

void detachAndScrapView(View child, RecyclerView.Recycler recycler)

Detach a child view and add it to a Recycler's scrap heap.

void detachAndScrapViewAt(int index, RecyclerView.Recycler recycler)

Detach a child view and add it to a Recycler's scrap heap.

void detachView(View child)

Temporarily detach a child view.

void detachViewAt(int index)

Temporarily detach a child view.

void endAnimation(View view)

Ends all animations on the view created by the RecyclerView.ItemAnimator.

View findContainingItemView(View view)

Traverses the ancestors of the given view and returns the item view that contains it and also a direct child of the LayoutManager.

View findViewByPosition(int position)

Finds the view which represents the given adapter position.

abstract RecyclerView.LayoutParams generateDefaultLayoutParams()

Create a default LayoutParams object for a child of the RecyclerView.

RecyclerView.LayoutParams generateLayoutParams(Context c, AttributeSet attrs)

Create a LayoutParams object suitable for this LayoutManager from an inflated layout resource.

RecyclerView.LayoutParams generateLayoutParams(ViewGroup.LayoutParams lp)

Create a LayoutParams object suitable for this LayoutManager, copying relevant values from the supplied LayoutParams object if possible.

int getBaseline()

Returns offset of the RecyclerView's text baseline from the its top boundary.

int getBottomDecorationHeight(View child)

Returns the total height of item decorations applied to child's bottom.

View getChildAt(int index)

Return the child view at the given index

int getChildCount()

Return the current number of child views attached to the parent RecyclerView.

static int getChildMeasureSpec(int parentSize, int parentMode, int padding, int childDimension, boolean canScroll)

Calculate a MeasureSpec value for measuring a child view in one dimension.

static int getChildMeasureSpec(int parentSize, int padding, int childDimension, boolean canScroll)

This method was deprecated in API level 23.2.0. use getChildMeasureSpec(int, int, int, int, boolean)

boolean getClipToPadding()

Check if the RecyclerView is configured to clip child views to its padding.

int getColumnCountForAccessibility(RecyclerView.Recycler recycler, RecyclerView.State state)

Returns the number of columns for accessibility.

int getDecoratedBottom(View child)

Returns the bottom edge of the given child view within its parent, offset by any applied ItemDecorations.

void getDecoratedBoundsWithMargins(View view, Rect outBounds)

Returns the bounds of the view including its decoration and margins.

int getDecoratedLeft(View child)

Returns the left edge of the given child view within its parent, offset by any applied ItemDecorations.

int getDecoratedMeasuredHeight(View child)

Returns the measured height of the given child, plus the additional size of any insets applied by ItemDecorations.

int getDecoratedMeasuredWidth(View child)

Returns the measured width of the given child, plus the additional size of any insets applied by ItemDecorations.

int getDecoratedRight(View child)

Returns the right edge of the given child view within its parent, offset by any applied ItemDecorations.

int getDecoratedTop(View child)

Returns the top edge of the given child view within its parent, offset by any applied ItemDecorations.

View getFocusedChild()

Returns the item View which has or contains focus.

int getHeight()

Return the height of the parent RecyclerView

int getHeightMode()

Return the height measurement spec mode of the RecyclerView.

int getItemCount()

Returns the number of items in the adapter bound to the parent RecyclerView.

int getItemViewType(View view)

Returns the View type defined by the adapter.

int getLayoutDirection()

Returns the resolved layout direction for this RecyclerView.

int getLeftDecorationWidth(View child)

Returns the total width of item decorations applied to child's left.

int getMinimumHeight()
int getMinimumWidth()
int getPaddingBottom()

Return the bottom padding of the parent RecyclerView

int getPaddingEnd()

Return the end padding of the parent RecyclerView

int getPaddingLeft()

Return the left padding of the parent RecyclerView

int getPaddingRight()

Return the right padding of the parent RecyclerView

int getPaddingStart()

Return the start padding of the parent RecyclerView

int getPaddingTop()

Return the top padding of the parent RecyclerView

int getPosition(View view)

Returns the adapter position of the item represented by the given View.

static RecyclerView.LayoutManager.Properties getProperties(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes)

Parse the xml attributes to get the most common properties used by layout managers.

int getRightDecorationWidth(View child)

Returns the total width of item decorations applied to child's right.

int getRowCountForAccessibility(RecyclerView.Recycler recycler, RecyclerView.State state)

Returns the number of rows for accessibility.

int getSelectionModeForAccessibility(RecyclerView.Recycler recycler, RecyclerView.State state)

Returns the selection mode for accessibility.

int getTopDecorationHeight(View child)

Returns the total height of item decorations applied to child's top.

void getTransformedBoundingBox(View child, boolean includeDecorInsets, Rect out)

Calculates the bounding box of the View while taking into account its matrix changes (translation, scale etc) with respect to the RecyclerView.

int getWidth()

Return the width of the parent RecyclerView

int getWidthMode()

Return the width measurement spec mode of the RecyclerView.

boolean hasFocus()

Returns true if the RecyclerView this LayoutManager is bound to has or contains focus.

void ignoreView(View view)

Flags a view so that it will not be scrapped or recycled.

boolean isAttachedToWindow()

Returns whether LayoutManager is currently attached to a RecyclerView which is attached to a window.

boolean isAutoMeasureEnabled()

Returns whether the LayoutManager uses the automatic measurement API or not.

boolean isFocused()

Returns true if the RecyclerView this LayoutManager is bound to has focus.

final boolean isItemPrefetchEnabled()

Sets whether the LayoutManager should be queried for views outside of its viewport while the UI thread is idle between frames.

boolean isLayoutHierarchical(RecyclerView.Recycler recycler, RecyclerView.State state)

Returns whether layout is hierarchical or not to be used for accessibility.

boolean isMeasurementCacheEnabled()

In addition to the View Framework's measurement cache, RecyclerView uses its own additional measurement cache for its children to avoid re-measuring them when not necessary.

boolean isSmoothScrolling()
boolean isViewPartiallyVisible(View child, boolean completelyVisible, boolean acceptEndPointInclusion)

Returns whether the given child view is partially or fully visible within the padded bounded area of RecyclerView, depending on the input parameters.

void layoutDecorated(View child, int left, int top, int right, int bottom)

Lay out the given child view within the RecyclerView using coordinates that include any current ItemDecorations.

void layoutDecoratedWithMargins(View child, int left, int top, int right, int bottom)

Lay out the given child view within the RecyclerView using coordinates that include any current ItemDecorations and margins.

void measureChild(View child, int widthUsed, int heightUsed)

Measure a child view using standard measurement policy, taking the padding of the parent RecyclerView and any added item decorations into account.

void measureChildWithMargins(View child, int widthUsed, int heightUsed)

Measure a child view using standard measurement policy, taking the padding of the parent RecyclerView, any added item decorations and the child margins into account.

void moveView(int fromIndex, int toIndex)

Moves a View from one position to another.

void offsetChildrenHorizontal(int dx)

Offset all child views attached to the parent RecyclerView by dx pixels along the horizontal axis.

void offsetChildrenVertical(int dy)

Offset all child views attached to the parent RecyclerView by dy pixels along the vertical axis.

void onAdapterChanged(Adapter oldAdapter, Adapter newAdapter)

Called if the RecyclerView this LayoutManager is bound to has a different adapter set.

boolean onAddFocusables(RecyclerView recyclerView, ArrayList<View> views, int direction, int focusableMode)

Called to populate focusable views within the RecyclerView.

void onAttachedToWindow(RecyclerView view)

Called when this LayoutManager is both attached to a RecyclerView and that RecyclerView is attached to a window.

void onDetachedFromWindow(RecyclerView view, RecyclerView.Recycler recycler)

Called when this LayoutManager is detached from its parent RecyclerView or when its parent RecyclerView is detached from its window.

void onDetachedFromWindow(RecyclerView view)

This method was deprecated in API level 22.0.0. override onDetachedFromWindow(RecyclerView, Recycler)

View onFocusSearchFailed(View focused, int direction, RecyclerView.Recycler recycler, RecyclerView.State state)

Called when searching for a focusable view in the given direction has failed for the current content of the RecyclerView.

void onInitializeAccessibilityEvent(AccessibilityEvent event)
void onInitializeAccessibilityEvent(RecyclerView.Recycler recycler, RecyclerView.State state, AccessibilityEvent event)

Called by the accessibility delegate to initialize an accessibility event.

void onInitializeAccessibilityNodeInfo(RecyclerView.Recycler recycler, RecyclerView.State state, AccessibilityNodeInfoCompat info)

Called by the AccessibilityDelegate when the information about the current layout should be populated.

void onInitializeAccessibilityNodeInfoForItem(RecyclerView.Recycler recycler, RecyclerView.State state, View host, AccessibilityNodeInfoCompat info)

Called by the AccessibilityDelegate when the accessibility information for a specific item should be populated.

View onInterceptFocusSearch(View focused, int direction)

This method gives a LayoutManager an opportunity to intercept the initial focus search before the default behavior of FocusFinder is used.

void onItemsAdded(RecyclerView recyclerView, int positionStart, int itemCount)

Called when items have been added to the adapter.

void onItemsChanged(RecyclerView recyclerView)

Called when notifyDataSetChanged() is triggered instead of giving detailed information on what has actually changed.

void onItemsMoved(RecyclerView recyclerView, int from, int to, int itemCount)

Called when an item is moved withing the adapter.

void onItemsRemoved(RecyclerView recyclerView, int positionStart, int itemCount)

Called when items have been removed from the adapter.

void onItemsUpdated(RecyclerView recyclerView, int positionStart, int itemCount)

Called when items have been changed in the adapter.

void onItemsUpdated(RecyclerView recyclerView, int positionStart, int itemCount, Object payload)

Called when items have been changed in the adapter and with optional payload.

void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state)

Lay out all relevant child views from the given adapter.

void onLayoutCompleted(RecyclerView.State state)

Called after a full layout calculation is finished.

void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state, int widthSpec, int heightSpec)

Measure the attached RecyclerView.

boolean onRequestChildFocus(RecyclerView parent, View child, View focused)

This method was deprecated in API level 22.0.0. Use onRequestChildFocus(RecyclerView, State, View, View)

boolean onRequestChildFocus(RecyclerView parent, RecyclerView.State state, View child, View focused)

Called when a descendant view of the RecyclerView requests focus.

void onRestoreInstanceState(Parcelable state)
Parcelable onSaveInstanceState()

Called when the LayoutManager should save its state.

void onScrollStateChanged(int state)

RecyclerView calls this method to notify LayoutManager that scroll state has changed.

boolean performAccessibilityAction(RecyclerView.Recycler recycler, RecyclerView.State state, int action, Bundle args)

Called by AccessibilityDelegate when an action is requested from the RecyclerView.

boolean performAccessibilityActionForItem(RecyclerView.Recycler recycler, RecyclerView.State state, View view, int action, Bundle args)

Called by AccessibilityDelegate when an accessibility action is requested on one of the children of LayoutManager.

void postOnAnimation(Runnable action)

Causes the Runnable to execute on the next animation time step.

void removeAllViews()

Remove all views from the currently attached RecyclerView.

void removeAndRecycleAllViews(RecyclerView.Recycler recycler)

Removes all views and recycles them using the given recycler.

void removeAndRecycleView(View child, RecyclerView.Recycler recycler)

Remove a child view and recycle it using the given Recycler.

void removeAndRecycleViewAt(int index, RecyclerView.Recycler recycler)

Remove a child view and recycle it using the given Recycler.

boolean removeCallbacks(Runnable action)

Removes the specified Runnable from the message queue.

void removeDetachedView(View child)

Finish removing a view that was previously temporarily detached.

void removeView(View child)

Remove a view from the currently attached RecyclerView if needed.

void removeViewAt(int index)

Remove a view from the currently attached RecyclerView if needed.

boolean requestChildRectangleOnScreen(RecyclerView parent, View child, Rect rect, boolean immediate, boolean focusedChildVisible)

Requests that the given child of the RecyclerView be positioned onto the screen.

boolean requestChildRectangleOnScreen(RecyclerView parent, View child, Rect rect, boolean immediate)

Called when a child of the RecyclerView wants a particular rectangle to be positioned onto the screen.

void requestLayout()

Calls RecyclerView#requestLayout on the underlying RecyclerView

void requestSimpleAnimationsInNextLayout()

A LayoutManager can call this method to force RecyclerView to run simple animations in the next layout pass, even if there is not any trigger to do so.

int scrollHorizontallyBy(int dx, RecyclerView.Recycler recycler, RecyclerView.State state)

Scroll horizontally by dx pixels in screen coordinates and return the distance traveled.

void scrollToPosition(int position)

Scroll to the specified adapter position.

int scrollVerticallyBy(int dy, RecyclerView.Recycler recycler, RecyclerView.State state)

Scroll vertically by dy pixels in screen coordinates and return the distance traveled.

void setAutoMeasureEnabled(boolean enabled)

Defines whether the layout should be measured by the RecyclerView or the LayoutManager wants to handle the layout measurements itself.

final void setItemPrefetchEnabled(boolean enabled)

Sets whether the LayoutManager should be queried for views outside of its viewport while the UI thread is idle between frames.

void setMeasuredDimension(int widthSize, int heightSize)

Set the measured dimensions of the host RecyclerView.

void setMeasuredDimension(Rect childrenBounds, int wSpec, int hSpec)

Sets the measured dimensions from the given bounding box of the children and the measurement specs that were passed into onMeasure(int, int).

void setMeasurementCacheEnabled(boolean measurementCacheEnabled)

Sets whether RecyclerView should use its own measurement cache for the children.

void smoothScrollToPosition(RecyclerView recyclerView, RecyclerView.State state, int position)

Smooth scroll to the specified adapter position.

void startSmoothScroll(RecyclerView.SmoothScroller smoothScroller)

Starts a smooth scroll using the provided SmoothScroller.

void stopIgnoringView(View view)

View can be scrapped and recycled again.

boolean supportsPredictiveItemAnimations()

Returns whether this LayoutManager supports automatic item animations.

Inherited methods

From class java.lang.Object

XML attributes

android.support.v7.recyclerview:reverseLayout

Related methods:

android.support.v7.recyclerview:spanCount

Related methods:

android.support.v7.recyclerview:stackFromEnd

Related methods:

android:orientation

Related methods:

Public constructors

RecyclerView.LayoutManager

added in version 22.0.0
RecyclerView.LayoutManager ()

Public methods

addDisappearingView

added in version 22.0.0
void addDisappearingView (View child, 
                int index)

To be called only during onLayoutChildren(Recycler, State) to add a view to the layout that is known to be going away, either because it has been removed or because it is actually not in the visible portion of the container but is being laid out in order to inform RecyclerView in how to animate the item out of view.

Views added via this method are going to be invisible to LayoutManager after the dispatchLayout pass is complete. They cannot be retrieved via getChildAt(int) or won't be included in getChildCount() method.

Parameters
child View: View to add and then remove with animation.

index int: Index of the view.

addDisappearingView

added in version 22.0.0
void addDisappearingView (View child)

To be called only during onLayoutChildren(Recycler, State) to add a view to the layout that is known to be going away, either because it has been removed or because it is actually not in the visible portion of the container but is being laid out in order to inform RecyclerView in how to animate the item out of view.

Views added via this method are going to be invisible to LayoutManager after the dispatchLayout pass is complete. They cannot be retrieved via getChildAt(int) or won't be included in getChildCount() method.

Parameters
child View: View to add and then remove with animation.

addView

added in version 22.0.0
void addView (View child, 
                int index)

Add a view to the currently attached RecyclerView if needed. LayoutManagers should use this method to add views obtained from a RecyclerView.Recycler using getViewForPosition(int).

Parameters
child View: View to add

index int: Index to add child at

addView

added in version 22.0.0
void addView (View child)

Add a view to the currently attached RecyclerView if needed. LayoutManagers should use this method to add views obtained from a RecyclerView.Recycler using getViewForPosition(int).

Parameters
child View: View to add

assertInLayoutOrScroll

added in version 22.0.0
void assertInLayoutOrScroll (String message)

Checks if RecyclerView is in the middle of a layout or scroll and throws an IllegalStateException if it is not.

Parameters
message String: The message for the exception. Can be null.

See also:

assertNotInLayoutOrScroll

added in version 22.0.0
void assertNotInLayoutOrScroll (String message)

Checks if RecyclerView is in the middle of a layout or scroll and throws an IllegalStateException if it is.

Parameters
message String: The message for the exception. Can be null.

See also:

attachView

added in version 22.0.0
void attachView (View child)

Reattach a previously detached view. This method should not be used to reattach views that were previously detachAndScrapView(android.view.View, RecyclerView.Recycler) scrapped}.

Parameters
child View: Child to reattach

attachView

added in version 22.0.0
void attachView (View child, 
                int index)

Reattach a previously detached view. This method should not be used to reattach views that were previously detachAndScrapView(android.view.View, RecyclerView.Recycler) scrapped}.

Parameters
child View: Child to reattach

index int: Intended child index for child

attachView

added in version 22.0.0
void attachView (View child, 
                int index, 
                RecyclerView.LayoutParams lp)

Reattach a previously detached view. This method should not be used to reattach views that were previously detachAndScrapView(android.view.View, RecyclerView.Recycler) scrapped}.

Parameters
child View: Child to reattach

index int: Intended child index for child

lp RecyclerView.LayoutParams: LayoutParams for child

calculateItemDecorationsForChild

added in version 22.0.0
void calculateItemDecorationsForChild (View child, 
                Rect outRect)

Calculates the item decor insets applied to the given child and updates the provided Rect instance with the inset values.

  • The Rect's left is set to the total width of left decorations.
  • The Rect's top is set to the total height of top decorations.
  • The Rect's right is set to the total width of right decorations.
  • The Rect's bottom is set to total height of bottom decorations.

Note that item decorations are automatically calculated when one of the LayoutManager's measure child methods is called. If you need to measure the child with custom specs via measure(int, int), you can use this method to get decorations.

Parameters
child View: The child view whose decorations should be calculated

outRect Rect: The Rect to hold result values

canScrollHorizontally

added in version 22.0.0
boolean canScrollHorizontally ()

Query if horizontal scrolling is currently supported. The default implementation returns false.

Returns
boolean True if this LayoutManager can scroll the current contents horizontally

canScrollVertically

added in version 22.0.0
boolean canScrollVertically ()

Query if vertical scrolling is currently supported. The default implementation returns false.

Returns
boolean True if this LayoutManager can scroll the current contents vertically

checkLayoutParams

added in version 22.0.0
boolean checkLayoutParams (RecyclerView.LayoutParams lp)

Determines the validity of the supplied LayoutParams object.

This should check to make sure that the object is of the correct type and all values are within acceptable ranges. The default implementation returns true for non-null params.

Parameters
lp RecyclerView.LayoutParams: LayoutParams object to check

Returns
boolean true if this LayoutParams object is valid, false otherwise

chooseSize

added in version 23.2.0
int chooseSize (int spec, 
                int desired, 
                int min)

Chooses a size from the given specs and parameters that is closest to the desired size and also complies with the spec.

Parameters
spec int: The measureSpec

desired int: The preferred measurement

min int: The minimum value

Returns
int A size that fits to the given specs

collectAdjacentPrefetchPositions

added in version 25.1.0
void collectAdjacentPrefetchPositions (int dx, 
                int dy, 
                RecyclerView.State state, 
                RecyclerView.LayoutManager.LayoutPrefetchRegistry layoutPrefetchRegistry)

Gather all positions from the LayoutManager to be prefetched, given specified momentum.

If item prefetch is enabled, this method is called in between traversals to gather which positions the LayoutManager will soon need, given upcoming movement in subsequent traversals.

The LayoutManager should call addPosition(int, int) for each item to be prepared, and these positions will have their ViewHolders created and bound, if there is sufficient time available, in advance of being needed by a scroll or layout.

Parameters
dx int: X movement component.

dy int: Y movement component.

state RecyclerView.State: State of RecyclerView

layoutPrefetchRegistry RecyclerView.LayoutManager.LayoutPrefetchRegistry: PrefetchRegistry to add prefetch entries into.

See also:

collectInitialPrefetchPositions

added in version 25.1.0
void collectInitialPrefetchPositions (int adapterItemCount, 
                RecyclerView.LayoutManager.LayoutPrefetchRegistry layoutPrefetchRegistry)

Gather all positions from the LayoutManager to be prefetched in preperation for its RecyclerView to come on screen, due to the movement of another, containing RecyclerView.

This method is only called when a RecyclerView is nested in another RecyclerView.

If item prefetch is enabled for this LayoutManager, as well in another containing LayoutManager, this method is called in between draw traversals to gather which positions this LayoutManager will first need, once it appears on the screen.

For example, if this LayoutManager represents a horizontally scrolling list within a vertically scrolling LayoutManager, this method would be called when the horizontal list is about to come onscreen.

The LayoutManager should call addPosition(int, int) for each item to be prepared, and these positions will have their ViewHolders created and bound, if there is sufficient time available, in advance of being needed by a scroll or layout.

Parameters
adapterItemCount int: number of items in the associated adapter.

layoutPrefetchRegistry RecyclerView.LayoutManager.LayoutPrefetchRegistry: PrefetchRegistry to add prefetch entries into.

See also:

computeHorizontalScrollExtent

added in version 22.0.0
int computeHorizontalScrollExtent (RecyclerView.State state)

Override this method if you want to support scroll bars.

Read computeHorizontalScrollExtent() for details.

Default implementation returns 0.

Parameters
state RecyclerView.State: Current state of RecyclerView

Returns
int The horizontal extent of the scrollbar's thumb

See also:

computeHorizontalScrollOffset

added in version 22.0.0
int computeHorizontalScrollOffset (RecyclerView.State state)

Override this method if you want to support scroll bars.

Read computeHorizontalScrollOffset() for details.

Default implementation returns 0.

Parameters
state RecyclerView.State: Current State of RecyclerView where you can find total item count

Returns
int The horizontal offset of the scrollbar's thumb

See also:

computeHorizontalScrollRange

added in version 22.0.0
int computeHorizontalScrollRange (RecyclerView.State state)

Override this method if you want to support scroll bars.

Read computeHorizontalScrollRange() for details.

Default implementation returns 0.

Parameters
state RecyclerView.State: Current State of RecyclerView where you can find total item count

Returns
int The total horizontal range represented by the vertical scrollbar

See also:

computeVerticalScrollExtent

added in version 22.0.0
int computeVerticalScrollExtent (RecyclerView.State state)

Override this method if you want to support scroll bars.

Read computeVerticalScrollExtent() for details.

Default implementation returns 0.

Parameters
state RecyclerView.State: Current state of RecyclerView

Returns
int The vertical extent of the scrollbar's thumb

See also:

computeVerticalScrollOffset

added in version 22.0.0
int computeVerticalScrollOffset (RecyclerView.State state)

Override this method if you want to support scroll bars.

Read computeVerticalScrollOffset() for details.

Default implementation returns 0.

Parameters
state RecyclerView.State: Current State of RecyclerView where you can find total item count

Returns
int The vertical offset of the scrollbar's thumb

See also:

computeVerticalScrollRange

added in version 22.0.0
int computeVerticalScrollRange (RecyclerView.State state)

Override this method if you want to support scroll bars.

Read computeVerticalScrollRange() for details.

Default implementation returns 0.

Parameters
state RecyclerView.State: Current State of RecyclerView where you can find total item count

Returns
int The total vertical range represented by the vertical scrollbar

See also:

detachAndScrapAttachedViews

added in version 22.0.0
void detachAndScrapAttachedViews (RecyclerView.Recycler recycler)

Temporarily detach and scrap all currently attached child views. Views will be scrapped into the given Recycler. The Recycler may prefer to reuse scrap views before other views that were previously recycled.

Parameters
recycler RecyclerView.Recycler: Recycler to scrap views into

detachAndScrapView

added in version 22.0.0
void detachAndScrapView (View child, 
                RecyclerView.Recycler recycler)

Detach a child view and add it to a Recycler's scrap heap.

Scrapping a view allows it to be rebound and reused to show updated or different data.

Parameters
child View: Child to detach and scrap

recycler RecyclerView.Recycler: Recycler to deposit the new scrap view into

detachAndScrapViewAt

added in version 22.0.0
void detachAndScrapViewAt (int index, 
                RecyclerView.Recycler recycler)

Detach a child view and add it to a Recycler's scrap heap.

Scrapping a view allows it to be rebound and reused to show updated or different data.

Parameters
index int: Index of child to detach and scrap

recycler RecyclerView.Recycler: Recycler to deposit the new scrap view into

detachView

added in version 22.0.0
void detachView (View child)

Temporarily detach a child view.

LayoutManagers may want to perform a lightweight detach operation to rearrange views currently attached to the RecyclerView. Generally LayoutManager implementations will want to use detachAndScrapView(android.view.View, RecyclerView.Recycler) so that the detached view may be rebound and reused.

If a LayoutManager uses this method to detach a view, it must reattach or fully remove the detached view before the LayoutManager entry point method called by RecyclerView returns.

Parameters
child View: Child to detach

detachViewAt

added in version 22.0.0
void detachViewAt (int index)

Temporarily detach a child view.

LayoutManagers may want to perform a lightweight detach operation to rearrange views currently attached to the RecyclerView. Generally LayoutManager implementations will want to use detachAndScrapView(android.view.View, RecyclerView.Recycler) so that the detached view may be rebound and reused.

If a LayoutManager uses this method to detach a view, it must reattach or fully remove the detached view before the LayoutManager entry point method called by RecyclerView returns.

Parameters
index int: Index of the child to detach

endAnimation

added in version 22.0.0
void endAnimation (View view)

Ends all animations on the view created by the RecyclerView.ItemAnimator.

Parameters
view View: The View for which the animations should be ended.

See also:

findContainingItemView

added in version 23.2.0
View findContainingItemView (View view)

Traverses the ancestors of the given view and returns the item view that contains it and also a direct child of the LayoutManager.

Note that this method may return null if the view is a child of the RecyclerView but not a child of the LayoutManager (e.g. running a disappear animation).

Parameters
view View: The view that is a descendant of the LayoutManager.

Returns
View The direct child of the LayoutManager which contains the given view or null if the provided view is not a descendant of this LayoutManager.

See also:

findViewByPosition

added in version 22.0.0
View findViewByPosition (int position)

Finds the view which represents the given adapter position.

This method traverses each child since it has no information about child order. Override this method to improve performance if your LayoutManager keeps data about child views.

If a view is ignored via ignoreView(View), it is also ignored by this method.

Parameters
position int: Position of the item in adapter

Returns
View The child view that represents the given position or null if the position is not laid out

generateDefaultLayoutParams

added in version 22.0.0
RecyclerView.LayoutParams generateDefaultLayoutParams ()

Create a default LayoutParams object for a child of the RecyclerView.

LayoutManagers will often want to use a custom LayoutParams type to store extra information specific to the layout. Client code should subclass RecyclerView.LayoutParams for this purpose.

Important: if you use your own custom LayoutParams type you must also override checkLayoutParams(LayoutParams), generateLayoutParams(android.view.ViewGroup.LayoutParams) and generateLayoutParams(android.content.Context, android.util.AttributeSet).

Returns
RecyclerView.LayoutParams A new LayoutParams for a child view

generateLayoutParams

added in version 22.0.0
RecyclerView.LayoutParams generateLayoutParams (Context c, 
                AttributeSet attrs)

Create a LayoutParams object suitable for this LayoutManager from an inflated layout resource.

Important: if you use your own custom LayoutParams type you must also override checkLayoutParams(LayoutParams), generateLayoutParams(android.view.ViewGroup.LayoutParams) and generateLayoutParams(android.content.Context, android.util.AttributeSet).

Parameters
c Context: Context for obtaining styled attributes

attrs AttributeSet: AttributeSet describing the supplied arguments

Returns
RecyclerView.LayoutParams a new LayoutParams object

generateLayoutParams

added in version 22.0.0
RecyclerView.LayoutParams generateLayoutParams (ViewGroup.LayoutParams lp)

Create a LayoutParams object suitable for this LayoutManager, copying relevant values from the supplied LayoutParams object if possible.

Important: if you use your own custom LayoutParams type you must also override checkLayoutParams(LayoutParams), generateLayoutParams(android.view.ViewGroup.LayoutParams) and generateLayoutParams(android.content.Context, android.util.AttributeSet).

Parameters
lp ViewGroup.LayoutParams: Source LayoutParams object to copy values from

Returns
RecyclerView.LayoutParams a new LayoutParams object

getBaseline

added in version 22.1.0
int getBaseline ()

Returns offset of the RecyclerView's text baseline from the its top boundary.

Returns
int The offset of the RecyclerView's text baseline from the its top boundary; -1 if there is no baseline.

getBottomDecorationHeight

added in version 22.0.0
int getBottomDecorationHeight (View child)

Returns the total height of item decorations applied to child's bottom.

Note that this value is not updated until the View is measured or calculateItemDecorationsForChild(View, Rect) is called.

Parameters
child View: Child to query

Returns
int The total height of item decorations applied to the child's bottom.

See also:

getChildAt

added in version 22.0.0
View getChildAt (int index)

Return the child view at the given index

Parameters
index int: Index of child to return

Returns
View Child view at index

getChildCount

added in version 22.0.0
int getChildCount ()

Return the current number of child views attached to the parent RecyclerView. This does not include child views that were temporarily detached and/or scrapped.

Returns
int Number of attached children

getChildMeasureSpec

added in version 23.2.0
int getChildMeasureSpec (int parentSize, 
                int parentMode, 
                int padding, 
                int childDimension, 
                boolean canScroll)

Calculate a MeasureSpec value for measuring a child view in one dimension.

Parameters
parentSize int: Size of the parent view where the child will be placed

parentMode int: The measurement spec mode of the parent

padding int: Total space currently consumed by other elements of parent

childDimension int: Desired size of the child view, or MATCH_PARENT/WRAP_CONTENT. Generally obtained from the child view's LayoutParams

canScroll boolean: true if the parent RecyclerView can scroll in this dimension

Returns
int a MeasureSpec value for the child view

getChildMeasureSpec

added in version 22.0.0
int getChildMeasureSpec (int parentSize, 
                int padding, 
                int childDimension, 
                boolean canScroll)

This method was deprecated in API level 23.2.0.
use getChildMeasureSpec(int, int, int, int, boolean)

Calculate a MeasureSpec value for measuring a child view in one dimension.

Parameters
parentSize int: Size of the parent view where the child will be placed

padding int: Total space currently consumed by other elements of the parent

childDimension int: Desired size of the child view, or MATCH_PARENT/WRAP_CONTENT. Generally obtained from the child view's LayoutParams

canScroll boolean: true if the parent RecyclerView can scroll in this dimension

Returns
int a MeasureSpec value for the child view

getClipToPadding

added in version 22.0.0
boolean getClipToPadding ()

Check if the RecyclerView is configured to clip child views to its padding.

Returns
boolean true if this RecyclerView clips children to its padding, false otherwise

getColumnCountForAccessibility

added in version 22.0.0
int getColumnCountForAccessibility (RecyclerView.Recycler recycler, 
                RecyclerView.State state)

Returns the number of columns for accessibility.

Default implementation returns the number of items in the adapter if LayoutManager supports horizontal scrolling or 1 if LayoutManager does not support horizontal scrolling.

Parameters
recycler RecyclerView.Recycler: The Recycler that can be used to convert view positions into adapter positions

state RecyclerView.State: The current state of RecyclerView

Returns
int The number of rows in LayoutManager for accessibility.

getDecoratedBottom

added in version 22.0.0
int getDecoratedBottom (View child)

Returns the bottom edge of the given child view within its parent, offset by any applied ItemDecorations.

Parameters
child View: Child to query

Returns
int Child bottom edge with offsets applied

See also:

getDecoratedBoundsWithMargins

added in version 24.0.0
void getDecoratedBoundsWithMargins (View view, 
                Rect outBounds)

Returns the bounds of the view including its decoration and margins.

Parameters
view View: The view element to check

outBounds Rect: A rect that will receive the bounds of the element including its decoration and margins.

getDecoratedLeft

added in version 22.0.0
int getDecoratedLeft (View child)

Returns the left edge of the given child view within its parent, offset by any applied ItemDecorations.

Parameters
child View: Child to query

Returns
int Child left edge with offsets applied

See also:

getDecoratedMeasuredHeight

added in version 22.0.0
int getDecoratedMeasuredHeight (View child)

Returns the measured height of the given child, plus the additional size of any insets applied by ItemDecorations.

Parameters
child View: Child view to query

Returns
int child's measured height plus ItemDecoration insets

See also:

getDecoratedMeasuredWidth

added in version 22.0.0
int getDecoratedMeasuredWidth (View child)

Returns the measured width of the given child, plus the additional size of any insets applied by ItemDecorations.

Parameters
child View: Child view to query

Returns
int child's measured width plus ItemDecoration insets

See also:

getDecoratedRight

added in version 22.0.0
int getDecoratedRight (View child)

Returns the right edge of the given child view within its parent, offset by any applied ItemDecorations.

Parameters
child View: Child to query

Returns
int Child right edge with offsets applied

See also:

getDecoratedTop

added in version 22.0.0
int getDecoratedTop (View child)

Returns the top edge of the given child view within its parent, offset by any applied ItemDecorations.

Parameters
child View: Child to query

Returns
int Child top edge with offsets applied

See also:

getFocusedChild

added in version 22.0.0
View getFocusedChild ()

Returns the item View which has or contains focus.

Returns
View A direct child of RecyclerView which has focus or contains the focused child.

getHeight

added in version 22.0.0
int getHeight ()

Return the height of the parent RecyclerView

Returns
int Height in pixels

getHeightMode

added in version 23.2.0
int getHeightMode ()

Return the height measurement spec mode of the RecyclerView.

This value is set only if the LayoutManager opts into the auto measure api via setAutoMeasureEnabled(boolean).

When RecyclerView is running a layout, this value is always set to EXACTLY even if it was measured with a different spec mode.

Returns
int Height measure spec mode.

See also:

getItemCount

added in version 22.0.0
int getItemCount ()

Returns the number of items in the adapter bound to the parent RecyclerView.

Note that this number is not necessarily equal to State#getItemCount(). In methods where RecyclerView.State is available, you should use State#getItemCount() instead. For more details, check the documentation for State#getItemCount().

Returns
int The number of items in the bound adapter

See also:

getItemViewType

added in version 22.0.0
int getItemViewType (View view)

Returns the View type defined by the adapter.

Parameters
view View: The view to query

Returns
int The type of the view assigned by the adapter.

getLayoutDirection

added in version 22.0.0
int getLayoutDirection ()

Returns the resolved layout direction for this RecyclerView.

Returns
int LAYOUT_DIRECTION_RTL if the layout direction is RTL or returns LAYOUT_DIRECTION_LTR if the layout direction is not RTL.

getLeftDecorationWidth

added in version 22.0.0
int getLeftDecorationWidth (View child)

Returns the total width of item decorations applied to child's left.

Note that this value is not updated until the View is measured or calculateItemDecorationsForChild(View, Rect) is called.

Parameters
child View: Child to query

Returns
int The total width of item decorations applied to the child's left.

See also:

getMinimumHeight

added in version 22.0.0
int getMinimumHeight ()

Returns
int The host RecyclerView's getMinimumHeight()

getMinimumWidth

added in version 22.0.0
int getMinimumWidth ()

Returns
int The host RecyclerView's getMinimumWidth()

getPaddingBottom

added in version 22.0.0
int getPaddingBottom ()

Return the bottom padding of the parent RecyclerView

Returns
int Padding in pixels

getPaddingEnd

added in version 22.0.0
int getPaddingEnd ()

Return the end padding of the parent RecyclerView

Returns
int Padding in pixels

getPaddingLeft

added in version 22.0.0
int getPaddingLeft ()

Return the left padding of the parent RecyclerView

Returns
int Padding in pixels

getPaddingRight

added in version 22.0.0
int getPaddingRight ()

Return the right padding of the parent RecyclerView

Returns
int Padding in pixels

getPaddingStart

added in version 22.0.0
int getPaddingStart ()

Return the start padding of the parent RecyclerView

Returns
int Padding in pixels

getPaddingTop

added in version 22.0.0
int getPaddingTop ()

Return the top padding of the parent RecyclerView

Returns
int Padding in pixels

getPosition

added in version 22.0.0
int getPosition (View view)

Returns the adapter position of the item represented by the given View. This does not contain any adapter changes that might have happened after the last layout.

Parameters
view View: The view to query

Returns
int The adapter position of the item which is rendered by this View.

getProperties

added in version 22.2.0
RecyclerView.LayoutManager.Properties getProperties (Context context, 
                AttributeSet attrs, 
                int defStyleAttr, 
                int defStyleRes)

Parse the xml attributes to get the most common properties used by layout managers.

Related XML Attributes:

Parameters
context Context

attrs AttributeSet

defStyleAttr int

defStyleRes int

Returns
RecyclerView.LayoutManager.Properties an object containing the properties as specified in the attrs.

getRightDecorationWidth

added in version 22.0.0
int getRightDecorationWidth (View child)

Returns the total width of item decorations applied to child's right.

Note that this value is not updated until the View is measured or calculateItemDecorationsForChild(View, Rect) is called.

Parameters
child View: Child to query

Returns
int The total width of item decorations applied to the child's right.

See also:

getRowCountForAccessibility

added in version 22.0.0
int getRowCountForAccessibility (RecyclerView.Recycler recycler, 
                RecyclerView.State state)

Returns the number of rows for accessibility.

Default implementation returns the number of items in the adapter if LayoutManager supports vertical scrolling or 1 if LayoutManager does not support vertical scrolling.

Parameters
recycler RecyclerView.Recycler: The Recycler that can be used to convert view positions into adapter positions

state RecyclerView.State: The current state of RecyclerView

Returns
int The number of rows in LayoutManager for accessibility.

getSelectionModeForAccessibility

added in version 22.0.0
int getSelectionModeForAccessibility (RecyclerView.Recycler recycler, 
                RecyclerView.State state)

Returns the selection mode for accessibility. Should be SELECTION_MODE_NONE, SELECTION_MODE_SINGLE or SELECTION_MODE_MULTIPLE.

Default implementation returns SELECTION_MODE_NONE.

Parameters
recycler RecyclerView.Recycler: The Recycler that can be used to convert view positions into adapter positions

state RecyclerView.State: The current state of RecyclerView

Returns
int Selection mode for accessibility. Default implementation returns SELECTION_MODE_NONE.

getTopDecorationHeight

added in version 22.0.0
int getTopDecorationHeight (View child)

Returns the total height of item decorations applied to child's top.

Note that this value is not updated until the View is measured or calculateItemDecorationsForChild(View, Rect) is called.

Parameters
child View: Child to query

Returns
int The total height of item decorations applied to the child's top.

See also:

getTransformedBoundingBox

added in version 24.0.0
void getTransformedBoundingBox (View child, 
                boolean includeDecorInsets, 
                Rect out)

Calculates the bounding box of the View while taking into account its matrix changes (translation, scale etc) with respect to the RecyclerView.

If includeDecorInsets is true, they are applied first before applying the View's matrix so that the decor offsets also go through the same transformation.

Parameters
child View: The ItemView whose bounding box should be calculated.

includeDecorInsets boolean: True if the decor insets should be included in the bounding box

out Rect: The rectangle into which the output will be written.

getWidth

added in version 22.0.0
int getWidth ()

Return the width of the parent RecyclerView

Returns
int Width in pixels

getWidthMode

added in version 23.2.0
int getWidthMode ()

Return the width measurement spec mode of the RecyclerView.

This value is set only if the LayoutManager opts into the auto measure api via setAutoMeasureEnabled(boolean).

When RecyclerView is running a layout, this value is always set to EXACTLY even if it was measured with a different spec mode.

Returns
int Width measure spec mode.

See also:

hasFocus

added in version 22.0.0
boolean hasFocus ()

Returns true if the RecyclerView this LayoutManager is bound to has or contains focus.

Returns
boolean true if the RecyclerView has or contains focus

See also:

ignoreView

added in version 22.0.0
void ignoreView (View view)

Flags a view so that it will not be scrapped or recycled.

Scope of ignoring a child is strictly restricted to position tracking, scrapping and recyling. Methods like removeAndRecycleAllViews(Recycler) will ignore the child whereas removeAllViews() or offsetChildrenHorizontal(int) will not ignore the child.

Before this child can be recycled again, you have to call stopIgnoringView(View).

You can call this method only if your LayoutManger is in onLayout or onScroll callback.

Parameters
view View: View to ignore.

See also:

isAttachedToWindow

added in version 22.1.0
boolean isAttachedToWindow ()

Returns whether LayoutManager is currently attached to a RecyclerView which is attached to a window.

Returns
boolean True if this LayoutManager is controlling a RecyclerView and the RecyclerView is attached to window.

isAutoMeasureEnabled

added in version 23.2.0
boolean isAutoMeasureEnabled ()

Returns whether the LayoutManager uses the automatic measurement API or not.

Returns
boolean True if the LayoutManager is measured by the RecyclerView or false if it measures itself.

See also:

isFocused

added in version 22.0.0
boolean isFocused ()

Returns true if the RecyclerView this LayoutManager is bound to has focus.

Returns
boolean True if the RecyclerView has focus, false otherwise.

See also:

isItemPrefetchEnabled

added in version 25.0.0
boolean isItemPrefetchEnabled ()

Sets whether the LayoutManager should be queried for views outside of its viewport while the UI thread is idle between frames.

Returns
boolean true if item prefetch is enabled, false otherwise

See also:

isLayoutHierarchical

added in version 22.0.0
boolean isLayoutHierarchical (RecyclerView.Recycler recycler, 
                RecyclerView.State state)

Returns whether layout is hierarchical or not to be used for accessibility.

Default implementation returns false.

Parameters
recycler RecyclerView.Recycler: The Recycler that can be used to convert view positions into adapter positions

state RecyclerView.State: The current state of RecyclerView

Returns
boolean True if layout is hierarchical.

isMeasurementCacheEnabled

added in version 23.2.0
boolean isMeasurementCacheEnabled ()

In addition to the View Framework's measurement cache, RecyclerView uses its own additional measurement cache for its children to avoid re-measuring them when not necessary. It is on by default but it can be turned off via setMeasurementCacheEnabled(boolean).

Returns
boolean True if measurement cache is enabled, false otherwise.

See also:

isSmoothScrolling

added in version 22.0.0
boolean isSmoothScrolling ()

Returns
boolean true if RecycylerView is currently in the state of smooth scrolling.

isViewPartiallyVisible

added in version 25.3.0
boolean isViewPartiallyVisible (View child, 
                boolean completelyVisible, 
                boolean acceptEndPointInclusion)

Returns whether the given child view is partially or fully visible within the padded bounded area of RecyclerView, depending on the input parameters. A view is partially visible if it has non-zero overlap with RV's padded bounded area. If acceptEndPointInclusion flag is set to true, it's also considered partially visible if it's located outside RV's bounds and it's hitting either RV's start or end bounds.

Parameters
child View: The child view to be examined.

completelyVisible boolean: If true, the method returns true if and only if the child is completely visible. If false, the method returns true if and only if the child is only partially visible (that is it will return false if the child is either completely visible or out of RV's bounds).

acceptEndPointInclusion boolean: If the view's endpoint intersection with RV's start of end bounds is enough to consider it partially visible, false otherwise.

Returns
boolean True if the given child is partially or fully visible, false otherwise.

layoutDecorated

added in version 22.0.0
void layoutDecorated (View child, 
                int left, 
                int top, 
                int right, 
                int bottom)

Lay out the given child view within the RecyclerView using coordinates that include any current ItemDecorations.

LayoutManagers should prefer working in sizes and coordinates that include item decoration insets whenever possible. This allows the LayoutManager to effectively ignore decoration insets within measurement and layout code. See the following methods:

Parameters
child View: Child to lay out

left int: Left edge, with item decoration insets included

top int: Top edge, with item decoration insets included

right int: Right edge, with item decoration insets included

bottom int: Bottom edge, with item decoration insets included

See also:

layoutDecoratedWithMargins

added in version 24.0.0
void layoutDecoratedWithMargins (View child, 
                int left, 
                int top, 
                int right, 
                int bottom)

Lay out the given child view within the RecyclerView using coordinates that include any current ItemDecorations and margins.

LayoutManagers should prefer working in sizes and coordinates that include item decoration insets whenever possible. This allows the LayoutManager to effectively ignore decoration insets within measurement and layout code. See the following methods:

Parameters
child View: Child to lay out

left int: Left edge, with item decoration insets and left margin included

top int: Top edge, with item decoration insets and top margin included

right int: Right edge, with item decoration insets and right margin included

bottom int: Bottom edge, with item decoration insets and bottom margin included

See also:

measureChild

added in version 22.0.0
void measureChild (View child, 
                int widthUsed, 
                int heightUsed)

Measure a child view using standard measurement policy, taking the padding of the parent RecyclerView and any added item decorations into account.

If the RecyclerView can be scrolled in either dimension the caller may pass 0 as the widthUsed or heightUsed parameters as they will be irrelevant.

Parameters
child View: Child view to measure

widthUsed int: Width in pixels currently consumed by other views, if relevant

heightUsed int: Height in pixels currently consumed by other views, if relevant

measureChildWithMargins

added in version 22.0.0
void measureChildWithMargins (View child, 
                int widthUsed, 
                int heightUsed)

Measure a child view using standard measurement policy, taking the padding of the parent RecyclerView, any added item decorations and the child margins into account.

If the RecyclerView can be scrolled in either dimension the caller may pass 0 as the widthUsed or heightUsed parameters as they will be irrelevant.

Parameters
child View: Child view to measure

widthUsed int: Width in pixels currently consumed by other views, if relevant

heightUsed int: Height in pixels currently consumed by other views, if relevant

moveView

added in version 22.0.0
void moveView (int fromIndex, 
                int toIndex)

Moves a View from one position to another.

Parameters
fromIndex int: The View's initial index

toIndex int: The View's target index

offsetChildrenHorizontal

added in version 22.0.0
void offsetChildrenHorizontal (int dx)

Offset all child views attached to the parent RecyclerView by dx pixels along the horizontal axis.

Parameters
dx int: Pixels to offset by

offsetChildrenVertical

added in version 22.0.0
void offsetChildrenVertical (int dy)

Offset all child views attached to the parent RecyclerView by dy pixels along the vertical axis.

Parameters
dy int: Pixels to offset by

onAdapterChanged

added in version 22.0.0
void onAdapterChanged (Adapter oldAdapter, 
                Adapter newAdapter)

Called if the RecyclerView this LayoutManager is bound to has a different adapter set. The LayoutManager may use this opportunity to clear caches and configure state such that it can relayout appropriately with the new data and potentially new view types.

The default implementation removes all currently attached views.

Parameters
oldAdapter Adapter: The previous adapter instance. Will be null if there was previously no adapter.

newAdapter Adapter: The new adapter instance. Might be null if setAdapter(RecyclerView.Adapter) is called with null.

onAddFocusables

added in version 22.0.0
boolean onAddFocusables (RecyclerView recyclerView, 
                ArrayList<View> views, 
                int direction, 
                int focusableMode)

Called to populate focusable views within the RecyclerView.

The LayoutManager implementation should return true if the default behavior of addFocusables(java.util.ArrayList, int) should be suppressed.

The default implementation returns false to trigger RecyclerView to fall back to the default ViewGroup behavior.

Parameters
recyclerView RecyclerView: The RecyclerView hosting this LayoutManager

views ArrayList: List of output views. This method should add valid focusable views to this list.

direction int: One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT, FOCUS_BACKWARD, FOCUS_FORWARD

focusableMode int: The type of focusables to be added.

Returns
boolean true to suppress the default behavior, false to add default focusables after this method returns.

See also:

onAttachedToWindow

added in version 22.0.0
void onAttachedToWindow (RecyclerView view)

Called when this LayoutManager is both attached to a RecyclerView and that RecyclerView is attached to a window.

If the RecyclerView is re-attached with the same LayoutManager and Adapter, it may not call onLayoutChildren(Recycler, State) if nothing has changed and a layout was not requested on the RecyclerView while it was detached.

Subclass implementations should always call through to the superclass implementation.

Parameters
view RecyclerView: The RecyclerView this LayoutManager is bound to

See also:

onDetachedFromWindow

added in version 22.0.0
void onDetachedFromWindow (RecyclerView view, 
                RecyclerView.Recycler recycler)

Called when this LayoutManager is detached from its parent RecyclerView or when its parent RecyclerView is detached from its window.

LayoutManager should clear all of its View references as another LayoutManager might be assigned to the RecyclerView.

If the RecyclerView is re-attached with the same LayoutManager and Adapter, it may not call onLayoutChildren(Recycler, State) if nothing has changed and a layout was not requested on the RecyclerView while it was detached.

If your LayoutManager has View references that it cleans in on-detach, it should also call requestLayout() to ensure that it is re-laid out when RecyclerView is re-attached.

Subclass implementations should always call through to the superclass implementation.

Parameters
view RecyclerView: The RecyclerView this LayoutManager is bound to

recycler RecyclerView.Recycler: The recycler to use if you prefer to recycle your children instead of keeping them around.

See also:

onDetachedFromWindow

added in version 22.0.0
void onDetachedFromWindow (RecyclerView view)

This method was deprecated in API level 22.0.0.
override onDetachedFromWindow(RecyclerView, Recycler)

Parameters
view RecyclerView

onFocusSearchFailed

added in version 22.0.0
View onFocusSearchFailed (View focused, 
                int direction, 
                RecyclerView.Recycler recycler, 
                RecyclerView.State state)

Called when searching for a focusable view in the given direction has failed for the current content of the RecyclerView.

This is the LayoutManager's opportunity to populate views in the given direction to fulfill the request if it can. The LayoutManager should attach and return the view to be focused, if a focusable view in the given direction is found. Otherwise, if all the existing (or the newly populated views) are unfocusable, it returns the next unfocusable view to become visible on the screen. This unfocusable view is typically the first view that's either partially or fully out of RV's padded bounded area in the given direction. The default implementation returns null.

Parameters
focused View: The currently focused view

direction int: One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT, FOCUS_BACKWARD, FOCUS_FORWARD or 0 for not applicable

recycler RecyclerView.Recycler: The recycler to use for obtaining views for currently offscreen items

state RecyclerView.State: Transient state of RecyclerView

Returns
View The chosen view to be focused if a focusable view is found, otherwise an unfocusable view to become visible onto the screen, else null.

onInitializeAccessibilityEvent

added in version 22.0.0
void onInitializeAccessibilityEvent (AccessibilityEvent event)

Parameters
event AccessibilityEvent

onInitializeAccessibilityEvent

added in version 22.0.0
void onInitializeAccessibilityEvent (RecyclerView.Recycler recycler, 
                RecyclerView.State state, 
                AccessibilityEvent event)

Called by the accessibility delegate to initialize an accessibility event.

Default implementation adds item count and scroll information to the event.

Parameters
recycler RecyclerView.Recycler: The Recycler that can be used to convert view positions into adapter positions

state RecyclerView.State: The current state of RecyclerView

event AccessibilityEvent: The event instance to initialize

See also:

onInitializeAccessibilityNodeInfo

added in version 22.0.0
void onInitializeAccessibilityNodeInfo (RecyclerView.Recycler recycler, 
                RecyclerView.State state, 
                AccessibilityNodeInfoCompat info)

Called by the AccessibilityDelegate when the information about the current layout should be populated.

Default implementation adds a AccessibilityNodeInfoCompat.CollectionInfoCompat.

You should override getRowCountForAccessibility(RecyclerView.Recycler, RecyclerView.State), getColumnCountForAccessibility(RecyclerView.Recycler, RecyclerView.State), isLayoutHierarchical(RecyclerView.Recycler, RecyclerView.State) and getSelectionModeForAccessibility(RecyclerView.Recycler, RecyclerView.State) for more accurate accessibility information.

Parameters
recycler RecyclerView.Recycler: The Recycler that can be used to convert view positions into adapter positions

state RecyclerView.State: The current state of RecyclerView

info AccessibilityNodeInfoCompat: The info that should be filled by the LayoutManager

See also:

onInitializeAccessibilityNodeInfoForItem

added in version 22.0.0
void onInitializeAccessibilityNodeInfoForItem (RecyclerView.Recycler recycler, 
                RecyclerView.State state, 
                View host, 
                AccessibilityNodeInfoCompat info)

Called by the AccessibilityDelegate when the accessibility information for a specific item should be populated.

Default implementation adds basic positioning information about the item.

Parameters
recycler RecyclerView.Recycler: The Recycler that can be used to convert view positions into adapter positions

state RecyclerView.State: The current state of RecyclerView

host View: The child for which accessibility node info should be populated

info AccessibilityNodeInfoCompat: The info to fill out about the item

See also:

onInterceptFocusSearch

added in version 22.0.0
View onInterceptFocusSearch (View focused, 
                int direction)

This method gives a LayoutManager an opportunity to intercept the initial focus search before the default behavior of FocusFinder is used. If this method returns null FocusFinder will attempt to find a focusable child view. If it fails then onFocusSearchFailed(View, int, RecyclerView.Recycler, RecyclerView.State) will be called to give the LayoutManager an opportunity to add new views for items that did not have attached views representing them. The LayoutManager should not add or remove views from this method.

Parameters
focused View: The currently focused view

direction int: One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT, FOCUS_BACKWARD, FOCUS_FORWARD

Returns
View A descendant view to focus or null to fall back to default behavior. The default implementation returns null.

onItemsAdded

added in version 22.0.0
void onItemsAdded (RecyclerView recyclerView, 
                int positionStart, 
                int itemCount)

Called when items have been added to the adapter. The LayoutManager may choose to requestLayout if the inserted items would require refreshing the currently visible set of child views. (e.g. currently empty space would be filled by appended items, etc.)

onItemsChanged

added in version 22.0.0
void onItemsChanged (RecyclerView recyclerView)

Called when notifyDataSetChanged() is triggered instead of giving detailed information on what has actually changed.

onItemsMoved

added in version 22.0.0
void onItemsMoved (RecyclerView recyclerView, 
                int from, 
                int to, 
                int itemCount)

Called when an item is moved withing the adapter.

Note that, an item may also change position in response to another ADD/REMOVE/MOVE operation. This callback is only called if and only if notifyItemMoved(int, int) is called.

onItemsRemoved

added in version 22.0.0
void onItemsRemoved (RecyclerView recyclerView, 
                int positionStart, 
                int itemCount)

Called when items have been removed from the adapter.

onItemsUpdated

added in version 22.0.0
void onItemsUpdated (RecyclerView recyclerView, 
                int positionStart, 
                int itemCount)

Called when items have been changed in the adapter. To receive payload, override onItemsUpdated(RecyclerView, int, int, Object) instead, then this callback will not be invoked.

onItemsUpdated

added in version 23.0.0
void onItemsUpdated (RecyclerView recyclerView, 
                int positionStart, 
                int itemCount, 
                Object payload)

Called when items have been changed in the adapter and with optional payload. Default implementation calls onItemsUpdated(RecyclerView, int, int).

onLayoutChildren

added in version 22.0.0
void onLayoutChildren (RecyclerView.Recycler recycler, 
                RecyclerView.State state)

Lay out all relevant child views from the given adapter. The LayoutManager is in charge of the behavior of item animations. By default, RecyclerView has a non-null ItemAnimator, and simple item animations are enabled. This means that add/remove operations on the adapter will result in animations to add new or appearing items, removed or disappearing items, and moved items. If a LayoutManager returns false from supportsPredictiveItemAnimations(), which is the default, and runs a normal layout operation during onLayoutChildren(Recycler, State), the RecyclerView will have enough information to run those animations in a simple way. For example, the default ItemAnimator, DefaultItemAnimator, will simply fade views in and out, whether they are actually added/removed or whether they are moved on or off the screen due to other add/remove operations.

A LayoutManager wanting a better item animation experience, where items can be animated onto and off of the screen according to where the items exist when they are not on screen, then the LayoutManager should return true from supportsPredictiveItemAnimations() and add additional logic to onLayoutChildren(Recycler, State). Supporting predictive animations means that onLayoutChildren(Recycler, State) will be called twice; once as a "pre" layout step to determine where items would have been prior to a real layout, and again to do the "real" layout. In the pre-layout phase, items will remember their pre-layout positions to allow them to be laid out appropriately. Also, removed items will be returned from the scrap to help determine correct placement of other items. These removed items should not be added to the child list, but should be used to help calculate correct positioning of other views, including views that were not previously onscreen (referred to as APPEARING views), but whose pre-layout offscreen position can be determined given the extra information about the pre-layout removed views.

The second layout pass is the real layout in which only non-removed views will be used. The only additional requirement during this pass is, if supportsPredictiveItemAnimations() returns true, to note which views exist in the child list prior to layout and which are not there after layout (referred to as DISAPPEARING views), and to position/layout those views appropriately, without regard to the actual bounds of the RecyclerView. This allows the animation system to know the location to which to animate these disappearing views.

The default LayoutManager implementations for RecyclerView handle all of these requirements for animations already. Clients of RecyclerView can either use one of these layout managers directly or look at their implementations of onLayoutChildren() to see how they account for the APPEARING and DISAPPEARING views.

Parameters
recycler RecyclerView.Recycler: Recycler to use for fetching potentially cached views for a position

state RecyclerView.State: Transient state of RecyclerView

onLayoutCompleted

added in version 24.0.0
void onLayoutCompleted (RecyclerView.State state)

Called after a full layout calculation is finished. The layout calculation may include multiple onLayoutChildren(Recycler, State) calls due to animations or layout measurement but it will include only one onLayoutCompleted(State) call. This method will be called at the end of layout(int, int, int, int) call.

This is a good place for the LayoutManager to do some cleanup like pending scroll position, saved state etc.

Parameters
state RecyclerView.State: Transient state of RecyclerView

onMeasure

added in version 22.0.0
void onMeasure (RecyclerView.Recycler recycler, 
                RecyclerView.State state, 
                int widthSpec, 
                int heightSpec)

Measure the attached RecyclerView. Implementations must call setMeasuredDimension(int, int) before returning.

The default implementation will handle EXACTLY measurements and respect the minimum width and height properties of the host RecyclerView if measured as UNSPECIFIED. AT_MOST measurements will be treated as EXACTLY and the RecyclerView will consume all available space.

Parameters
recycler RecyclerView.Recycler: Recycler

state RecyclerView.State: Transient state of RecyclerView

widthSpec int: Width View.MeasureSpec

heightSpec int: Height View.MeasureSpec

onRequestChildFocus

added in version 22.0.0
boolean onRequestChildFocus (RecyclerView parent, 
                View child, 
                View focused)

This method was deprecated in API level 22.0.0.
Use onRequestChildFocus(RecyclerView, State, View, View)

Parameters
parent RecyclerView

child View

focused View

Returns
boolean

onRequestChildFocus

added in version 22.0.0
boolean onRequestChildFocus (RecyclerView parent, 
                RecyclerView.State state, 
                View child, 
                View focused)

Called when a descendant view of the RecyclerView requests focus.

A LayoutManager wishing to keep focused views aligned in a specific portion of the view may implement that behavior in an override of this method.

If the LayoutManager executes different behavior that should override the default behavior of scrolling the focused child on screen instead of running alongside it, this method should return true.

Parameters
parent RecyclerView: The RecyclerView hosting this LayoutManager

state RecyclerView.State: Current state of RecyclerView

child View: Direct child of the RecyclerView containing the newly focused view

focused View: The newly focused view. This may be the same view as child or it may be null

Returns
boolean true if the default scroll behavior should be suppressed

onRestoreInstanceState

added in version 22.0.0
void onRestoreInstanceState (Parcelable state)

Parameters
state Parcelable

onSaveInstanceState

added in version 22.0.0
Parcelable onSaveInstanceState ()

Called when the LayoutManager should save its state. This is a good time to save your scroll position, configuration and anything else that may be required to restore the same layout state if the LayoutManager is recreated.

RecyclerView does NOT verify if the LayoutManager has changed between state save and restore. This will let you share information between your LayoutManagers but it is also your responsibility to make sure they use the same parcelable class.

Returns
Parcelable Necessary information for LayoutManager to be able to restore its state

onScrollStateChanged

added in version 22.0.0
void onScrollStateChanged (int state)

RecyclerView calls this method to notify LayoutManager that scroll state has changed.

Parameters
state int: The new scroll state for RecyclerView

performAccessibilityAction

added in version 22.0.0
boolean performAccessibilityAction (RecyclerView.Recycler recycler, 
                RecyclerView.State state, 
                int action, 
                Bundle args)

Called by AccessibilityDelegate when an action is requested from the RecyclerView.

Parameters
recycler RecyclerView.Recycler: The Recycler that can be used to convert view positions into adapter positions

state RecyclerView.State: The current state of RecyclerView

action int: The action to perform

args Bundle: Optional action arguments

Returns
boolean

See also:

performAccessibilityActionForItem

added in version 22.0.0
boolean performAccessibilityActionForItem (RecyclerView.Recycler recycler, 
                RecyclerView.State state, 
                View view, 
                int action, 
                Bundle args)

Called by AccessibilityDelegate when an accessibility action is requested on one of the children of LayoutManager.

Default implementation does not do anything.

Parameters
recycler RecyclerView.Recycler: The Recycler that can be used to convert view positions into adapter positions

state RecyclerView.State: The current state of RecyclerView

view View: The child view on which the action is performed

action int: The action to perform

args Bundle: Optional action arguments

Returns
boolean true if action is handled

See also:

postOnAnimation

added in version 22.1.0
void postOnAnimation (Runnable action)

Causes the Runnable to execute on the next animation time step. The runnable will be run on the user interface thread.

Calling this method when LayoutManager is not attached to a RecyclerView has no effect.

Parameters
action Runnable: The Runnable that will be executed.

See also:

removeAllViews

added in version 22.0.0
void removeAllViews ()

Remove all views from the currently attached RecyclerView. This will not recycle any of the affected views; the LayoutManager is responsible for doing so if desired.

removeAndRecycleAllViews

added in version 22.0.0
void removeAndRecycleAllViews (RecyclerView.Recycler recycler)

Removes all views and recycles them using the given recycler.

If you want to clean cached views as well, you should call clear() too.

If a View is marked as "ignored", it is not removed nor recycled.

Parameters
recycler RecyclerView.Recycler: Recycler to use to recycle children

See also:

removeAndRecycleView

added in version 22.0.0
void removeAndRecycleView (View child, 
                RecyclerView.Recycler recycler)

Remove a child view and recycle it using the given Recycler.

Parameters
child View: Child to remove and recycle

recycler RecyclerView.Recycler: Recycler to use to recycle child

removeAndRecycleViewAt

added in version 22.0.0
void removeAndRecycleViewAt (int index, 
                RecyclerView.Recycler recycler)

Remove a child view and recycle it using the given Recycler.

Parameters
index int: Index of child to remove and recycle

recycler RecyclerView.Recycler: Recycler to use to recycle child

removeCallbacks

added in version 22.1.0
boolean removeCallbacks (Runnable action)

Removes the specified Runnable from the message queue.

Calling this method when LayoutManager is not attached to a RecyclerView has no effect.

Parameters
action Runnable: The Runnable to remove from the message handling queue

Returns
boolean true if RecyclerView could ask the Handler to remove the Runnable, false otherwise. When the returned value is true, the Runnable may or may not have been actually removed from the message queue (for instance, if the Runnable was not in the queue already.)

See also:

removeDetachedView

added in version 22.0.0
void removeDetachedView (View child)

Finish removing a view that was previously temporarily detached.

Parameters
child View: Detached child to remove

removeView

added in version 22.0.0
void removeView (View child)

Remove a view from the currently attached RecyclerView if needed. LayoutManagers should use this method to completely remove a child view that is no longer needed. LayoutManagers should strongly consider recycling removed views using recycleView(android.view.View).

Parameters
child View: View to remove

removeViewAt

added in version 22.0.0
void removeViewAt (int index)

Remove a view from the currently attached RecyclerView if needed. LayoutManagers should use this method to completely remove a child view that is no longer needed. LayoutManagers should strongly consider recycling removed views using recycleView(android.view.View).

Parameters
index int: Index of the child view to remove

requestChildRectangleOnScreen

added in version 25.3.0
boolean requestChildRectangleOnScreen (RecyclerView parent, 
                View child, 
                Rect rect, 
                boolean immediate, 
                boolean focusedChildVisible)

Requests that the given child of the RecyclerView be positioned onto the screen. This method can be called for both unfocusable and focusable child views. For unfocusable child views, focusedChildVisible is typically true in which case, layout manager makes the child view visible only if the currently focused child stays in-bounds of RV.

Parameters
parent RecyclerView: The parent RecyclerView.

child View: The direct child making the request.

rect Rect: The rectangle in the child's coordinates the child wishes to be on the screen.

immediate boolean: True to forbid animated or delayed scrolling, false otherwise

focusedChildVisible boolean: Whether the currently focused view must stay visible.

Returns
boolean Whether the group scrolled to handle the operation

requestChildRectangleOnScreen

added in version 22.0.0
boolean requestChildRectangleOnScreen (RecyclerView parent, 
                View child, 
                Rect rect, 
                boolean immediate)

Called when a child of the RecyclerView wants a particular rectangle to be positioned onto the screen. See requestChildRectangleOnScreen(android.view.View, android.graphics.Rect, boolean) for more details.

The base implementation will attempt to perform a standard programmatic scroll to bring the given rect into view, within the padded area of the RecyclerView.

Parameters
parent RecyclerView

child View: The direct child making the request.

rect Rect: The rectangle in the child's coordinates the child wishes to be on the screen.

immediate boolean: True to forbid animated or delayed scrolling, false otherwise

Returns
boolean Whether the group scrolled to handle the operation

requestLayout

added in version 22.0.0
void requestLayout ()

Calls RecyclerView#requestLayout on the underlying RecyclerView

requestSimpleAnimationsInNextLayout

added in version 22.0.0
void requestSimpleAnimationsInNextLayout ()

A LayoutManager can call this method to force RecyclerView to run simple animations in the next layout pass, even if there is not any trigger to do so. (e.g. adapter data change).

Note that, calling this method will not guarantee that RecyclerView will run animations at all. For example, if there is not any RecyclerView.ItemAnimator set, RecyclerView will not run any animations but will still clear this flag after the layout is complete.

scrollHorizontallyBy

added in version 22.0.0
int scrollHorizontallyBy (int dx, 
                RecyclerView.Recycler recycler, 
                RecyclerView.State state)

Scroll horizontally by dx pixels in screen coordinates and return the distance traveled. The default implementation does nothing and returns 0.

Parameters
dx int: distance to scroll by in pixels. X increases as scroll position approaches the right.

recycler RecyclerView.Recycler: Recycler to use for fetching potentially cached views for a position

state RecyclerView.State: Transient state of RecyclerView

Returns
int The actual distance scrolled. The return value will be negative if dx was negative and scrolling proceeeded in that direction. Math.abs(result) may be less than dx if a boundary was reached.

scrollToPosition

added in version 22.0.0
void scrollToPosition (int position)

Scroll to the specified adapter position. Actual position of the item on the screen depends on the LayoutManager implementation.

Parameters
position int: Scroll to this adapter position.

scrollVerticallyBy

added in version 22.0.0
int scrollVerticallyBy (int dy, 
                RecyclerView.Recycler recycler, 
                RecyclerView.State state)

Scroll vertically by dy pixels in screen coordinates and return the distance traveled. The default implementation does nothing and returns 0.

Parameters
dy int: distance to scroll in pixels. Y increases as scroll position approaches the bottom.

recycler RecyclerView.Recycler: Recycler to use for fetching potentially cached views for a position

state RecyclerView.State: Transient state of RecyclerView

Returns
int The actual distance scrolled. The return value will be negative if dy was negative and scrolling proceeeded in that direction. Math.abs(result) may be less than dy if a boundary was reached.

setAutoMeasureEnabled

added in version 23.2.0
void setAutoMeasureEnabled (boolean enabled)

Defines whether the layout should be measured by the RecyclerView or the LayoutManager wants to handle the layout measurements itself.

This method is usually called by the LayoutManager with value true if it wants to support WRAP_CONTENT. If you are using a public LayoutManager but want to customize the measurement logic, you can call this method with false and override onMeasure(int, int) to implement your custom measurement logic.

AutoMeasure is a convenience mechanism for LayoutManagers to easily wrap their content or handle various specs provided by the RecyclerView's parent. It works by calling onLayoutChildren(Recycler, State) during an onMeasure(int, int) call, then calculating desired dimensions based on children's positions. It does this while supporting all existing animation capabilities of the RecyclerView.

AutoMeasure works as follows:

  1. LayoutManager should call setAutoMeasureEnabled(true) to enable it. All of the framework LayoutManagers use auto-measure.
  2. When onMeasure(int, int) is called, if the provided specs are exact, RecyclerView will only call LayoutManager's onMeasure and return without doing any layout calculation.
  3. If one of the layout specs is not EXACT, the RecyclerView will start the layout process in onMeasure call. It will process all pending Adapter updates and decide whether to run a predictive layout or not. If it decides to do so, it will first call onLayoutChildren(Recycler, State) with isPreLayout() set to true. At this stage, getWidth() and getHeight() will still return the width and height of the RecyclerView as of the last layout calculation.

    After handling the predictive case, RecyclerView will call onLayoutChildren(Recycler, State) with isMeasuring() set to true and isPreLayout() set to false. The LayoutManager can access the measurement specs via getHeight(), getHeightMode(), getWidth() and getWidthMode().

  4. After the layout calculation, RecyclerView sets the measured width & height by calculating the bounding box for the children (+ RecyclerView's padding). The LayoutManagers can override setMeasuredDimension(Rect, int, int) to choose different values. For instance, GridLayoutManager overrides this value to handle the case where if it is vertical and has 3 columns but only 2 items, it should still measure its width to fit 3 items, not 2.
  5. Any following on measure call to the RecyclerView will run onLayoutChildren(Recycler, State) with isMeasuring() set to true and isPreLayout() set to false. RecyclerView will take care of which views are actually added / removed / moved / changed for animations so that the LayoutManager should not worry about them and handle each onLayoutChildren(Recycler, State) call as if it is the last one.
  6. When measure is complete and RecyclerView's onLayout(boolean, int, int, int, int) method is called, RecyclerView checks whether it already did layout calculations during the measure pass and if so, it re-uses that information. It may still decide to call onLayoutChildren(Recycler, State) if the last measure spec was different from the final dimensions or adapter contents have changed between the measure call and the layout call.
  7. Finally, animations are calculated and run as usual.

Parameters
enabled boolean: True if the Layout should be measured by the RecyclerView, false if the LayoutManager wants to measure itself.

See also:

setItemPrefetchEnabled

added in version 25.0.0
void setItemPrefetchEnabled (boolean enabled)

Sets whether the LayoutManager should be queried for views outside of its viewport while the UI thread is idle between frames.

If enabled, the LayoutManager will be queried for items to inflate/bind in between view system traversals on devices running API 21 or greater. Default value is true.

On platforms API level 21 and higher, the UI thread is idle between passing a frame to RenderThread and the starting up its next frame at the next VSync pulse. By prefetching out of window views in this time period, delays from inflation and view binding are much less likely to cause jank and stuttering during scrolls and flings.

While prefetch is enabled, it will have the side effect of expanding the effective size of the View cache to hold prefetched views.

Parameters
enabled boolean: True if items should be prefetched in between traversals.

See also:

setMeasuredDimension

added in version 22.0.0
void setMeasuredDimension (int widthSize, 
                int heightSize)

Set the measured dimensions of the host RecyclerView.

Parameters
widthSize int: Measured width

heightSize int: Measured height

setMeasuredDimension

added in version 23.2.0
void setMeasuredDimension (Rect childrenBounds, 
                int wSpec, 
                int hSpec)

Sets the measured dimensions from the given bounding box of the children and the measurement specs that were passed into onMeasure(int, int). It is called after the RecyclerView calls onLayoutChildren(Recycler, State) during a measurement pass.

This method should call setMeasuredDimension(int, int).

The default implementation adds the RecyclerView's padding to the given bounding box then caps the value to be within the given measurement specs.

This method is only called if the LayoutManager opted into the auto measurement API.

Parameters
childrenBounds Rect: The bounding box of all children

wSpec int: The widthMeasureSpec that was passed into the RecyclerView.

hSpec int: The heightMeasureSpec that was passed into the RecyclerView.

See also:

setMeasurementCacheEnabled

added in version 23.2.0
void setMeasurementCacheEnabled (boolean measurementCacheEnabled)

Sets whether RecyclerView should use its own measurement cache for the children. This is a more aggressive cache than the framework uses.

Parameters
measurementCacheEnabled boolean: True to enable the measurement cache, false otherwise.

See also:

smoothScrollToPosition

added in version 22.0.0
void smoothScrollToPosition (RecyclerView recyclerView, 
                RecyclerView.State state, 
                int position)

Smooth scroll to the specified adapter position.

To support smooth scrolling, override this method, create your RecyclerView.SmoothScroller instance and call startSmoothScroll(SmoothScroller).

Parameters
recyclerView RecyclerView: The RecyclerView to which this layout manager is attached

state RecyclerView.State: Current State of RecyclerView

position int: Scroll to this adapter position.

startSmoothScroll

added in version 22.0.0
void startSmoothScroll (RecyclerView.SmoothScroller smoothScroller)

Starts a smooth scroll using the provided SmoothScroller.

Calling this method will cancel any previous smooth scroll request.

Parameters
smoothScroller RecyclerView.SmoothScroller: Instance which defines how smooth scroll should be animated

stopIgnoringView

added in version 22.0.0
void stopIgnoringView (View view)

View can be scrapped and recycled again.

Note that calling this method removes all information in the view holder.

You can call this method only if your LayoutManger is in onLayout or onScroll callback.

Parameters
view View: View to ignore.

supportsPredictiveItemAnimations

added in version 22.0.0
boolean supportsPredictiveItemAnimations ()

Returns whether this LayoutManager supports automatic item animations. A LayoutManager wishing to support item animations should obey certain rules as outlined in onLayoutChildren(Recycler, State). The default return value is false, so subclasses of LayoutManager will not get predictive item animations by default.

Whether item animations are enabled in a RecyclerView is determined both by the return value from this method and the ItemAnimator set on the RecyclerView itself. If the RecyclerView has a non-null ItemAnimator but this method returns false, then simple item animations will be enabled, in which views that are moving onto or off of the screen are simply faded in/out. If the RecyclerView has a non-null ItemAnimator and this method returns true, then there will be two calls to onLayoutChildren(Recycler, State) to setup up the information needed to more intelligently predict where appearing and disappearing views should be animated from/to.

Returns
boolean true if predictive item animations should be enabled, false otherwise

This site uses cookies to store your preferences for site-specific language and display options.

Get the latest Android developer news and tips that will help you find success on Google Play.

* Required Fields

Hooray!

Browse this site in ?

You requested a page in , but your language preference for this site is .

Would you like to change your language preference and browse this site in ? If you want to change your language preference later, use the language menu at the bottom of each page.

This class requires API level or higher

This doc is hidden because your selected API level for the documentation is . You can change the documentation API level with the selector above the left navigation.

For more information about specifying the API level your app requires, read Supporting Different Platform Versions.

Take a short survey?
Help us improve the Android developer experience.
(Sep 2017 survey)