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added in version 22.1.0
belongs to Maven artifact com.android.support:recyclerview-v7:28.0.0-alpha1

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

RecyclerView_android_orientation  
RecyclerView_reverseLayout  
RecyclerView_spanCount  
RecyclerView_stackFromEnd  

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 24.1.0. 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()

Returns the height that is currently relevant to the LayoutManager.

int getHeightMode()

Return the height measurement spec mode that is currently relevant to the LayoutManager.

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()

Returns the width that is currently relevant to the LayoutManager.

int getWidthMode()

Return the width measurement spec mode that is currently relevant to the LayoutManager.

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 measuring pass of layout should use the AutoMeasure mechanism of RecyclerView or if it should be done by the LayoutManager's implementation of onMeasure(Recycler, State, int, int).

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 via setAdapter(Adapter) or swapAdapter(Adapter, boolean).

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 22.1.0. 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 in response to a call to notifyDataSetChanged() or swapAdapter(Adapter, boolean) ()} and signals that the the entire data set has 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 22.1.0. 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)

This method was deprecated in API level 27.1.0. Implementors of LayoutManager should define whether or not it uses AutoMeasure by overriding isAutoMeasureEnabled().

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 "predictive item animations".

Inherited methods

From class java.lang.Object

XML attributes

RecyclerView_android_orientation

Related methods:

RecyclerView_reverseLayout

Related methods:

RecyclerView_spanCount

Related methods:

RecyclerView_stackFromEnd

Related methods:

Public constructors

RecyclerView.LayoutManager

added in version 22.1.0
RecyclerView.LayoutManager ()

Public methods

addDisappearingView

added in version 22.1.0
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 22.1.0
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 22.1.0
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 22.1.0
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 22.1.0
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.

assertNotInLayoutOrScroll

added in version 22.1.0
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.

attachView

added in version 22.1.0
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 22.1.0
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 22.1.0
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 22.1.0
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 22.1.0
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 22.1.0
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 22.1.0
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 24.1.0
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.

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.

computeHorizontalScrollExtent

added in version 22.1.0
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

computeHorizontalScrollOffset

added in version 22.1.0
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

computeHorizontalScrollRange

added in version 22.1.0
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

computeVerticalScrollExtent

added in version 22.1.0
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

computeVerticalScrollOffset

added in version 22.1.0
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

computeVerticalScrollRange

added in version 22.1.0
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

detachAndScrapAttachedViews

added in version 22.1.0
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 22.1.0
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 22.1.0
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 22.1.0
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 22.1.0
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 22.1.0
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 24.1.0
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.