added in version 22.1.0
belongs to Maven artifact com.android.support:recyclerview-v7:28.0.0-alpha1
Summary: Nested Classes | XML Attrs | Inherited XML Attrs | Constants | Inherited Constants | Ctors | Methods | Inherited Methods | [Expand All]

GridLayoutManager

public class GridLayoutManager
extends LinearLayoutManager

java.lang.Object
   ↳ android.support.v7.widget.RecyclerView.LayoutManager
     ↳ android.support.v7.widget.LinearLayoutManager
       ↳ android.support.v7.widget.GridLayoutManager

A RecyclerView.LayoutManager implementations that lays out items in a grid.

By default, each item occupies 1 span. You can change it by providing a custom GridLayoutManager.SpanSizeLookup instance via setSpanSizeLookup(SpanSizeLookup).

Summary

Nested classes

class GridLayoutManager.DefaultSpanSizeLookup

Default implementation for GridLayoutManager.SpanSizeLookup. 

class GridLayoutManager.LayoutParams

LayoutParams used by GridLayoutManager. 

class GridLayoutManager.SpanSizeLookup

A helper class to provide the number of spans each item occupies. 

XML attributes

RecyclerView_spanCount  

Inherited XML attributes

From class android.support.v7.widget.LinearLayoutManager
From class android.support.v7.widget.RecyclerView.LayoutManager

Constants

int DEFAULT_SPAN_COUNT

Inherited constants

From class android.support.v7.widget.LinearLayoutManager

Public constructors

GridLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes)

Constructor used when layout manager is set in XML by RecyclerView attribute "layoutManager".

GridLayoutManager(Context context, int spanCount)

Creates a vertical GridLayoutManager

GridLayoutManager(Context context, int spanCount, int orientation, boolean reverseLayout)

Public methods

boolean checkLayoutParams(RecyclerView.LayoutParams lp)

Determines the validity of the supplied LayoutParams object.

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

Returns the number of columns for accessibility.

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

Returns the number of rows for accessibility.

int getSpanCount()

Returns the number of spans laid out by this grid.

GridLayoutManager.SpanSizeLookup getSpanSizeLookup()

Returns the current GridLayoutManager.SpanSizeLookup used by the GridLayoutManager.

View onFocusSearchFailed(View focused, int focusDirection, 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 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.

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, 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.

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

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

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

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

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 setSpanCount(int spanCount)

Sets the number of spans to be laid out.

void setSpanSizeLookup(GridLayoutManager.SpanSizeLookup spanSizeLookup)

Sets the source to get the number of spans occupied by each item in the adapter.

void setStackFromEnd(boolean stackFromEnd)

stackFromEnd is not supported by GridLayoutManager.

boolean supportsPredictiveItemAnimations()

Returns whether this LayoutManager supports "predictive item animations".

Inherited methods

From class android.support.v7.widget.LinearLayoutManager
From class android.support.v7.widget.RecyclerView.LayoutManager
From class java.lang.Object
From interface android.support.v7.widget.helper.ItemTouchHelper.ViewDropHandler
From interface android.support.v7.widget.RecyclerView.SmoothScroller.ScrollVectorProvider

XML attributes

RecyclerView_spanCount

Related methods:

Constants

DEFAULT_SPAN_COUNT

added in version 22.1.0 
int DEFAULT_SPAN_COUNT

Constant Value: -1 (0xffffffff)

Public constructors

GridLayoutManager

added in version 24.1.0
GridLayoutManager (Context context, 
                AttributeSet attrs, 
                int defStyleAttr, 
                int defStyleRes)

Constructor used when layout manager is set in XML by RecyclerView attribute "layoutManager". If spanCount is not specified in the XML, it defaults to a single column.

Related XML Attributes:

Parameters
context Context

attrs AttributeSet

defStyleAttr int

defStyleRes int

GridLayoutManager

added in version 22.1.0
GridLayoutManager (Context context, 
                int spanCount)

Creates a vertical GridLayoutManager

Parameters
context Context: Current context, will be used to access resources.
spanCount int: The number of columns in the grid

GridLayoutManager

added in version 22.1.0
GridLayoutManager (Context context, 
                int spanCount, 
                int orientation, 
                boolean reverseLayout)

Parameters
context Context: Current context, will be used to access resources.
spanCount int: The number of columns or rows in the grid
orientation int: Layout orientation. Should be HORIZONTAL or VERTICAL.
reverseLayout boolean: When set to true, layouts from end to start.

Public methods

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

generateDefaultLayoutParams

added in version 22.1.0
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 22.1.0
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 22.1.0
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

getColumnCountForAccessibility

added in version 22.1.0
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.

getRowCountForAccessibility

added in version 22.1.0
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.

getSpanCount

added in version 22.1.0
int getSpanCount ()

Returns the number of spans laid out by this grid.

Returns
int The number of spans

See also:

getSpanSizeLookup

added in version 22.1.0
GridLayoutManager.SpanSizeLookup getSpanSizeLookup ()

Returns the current GridLayoutManager.SpanSizeLookup used by the GridLayoutManager.

Returns
GridLayoutManager.SpanSizeLookup The current GridLayoutManager.SpanSizeLookup used by the GridLayoutManager.

onFocusSearchFailed

added in version 22.1.0
View onFocusSearchFailed (View focused, 
                int focusDirection, 
                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
focusDirection 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.

onInitializeAccessibilityNodeInfoForItem

added in version 22.1.0
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

onItemsAdded

added in version 22.1.0
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 22.1.0
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.

onItemsMoved

added in version 22.1.0
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 22.1.0
void onItemsRemoved (RecyclerView recyclerView, 
                int positionStart, 
                int itemCount)

Called when items have been removed from the adapter.

onItemsUpdated

added in version 24.1.0
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 22.1.0
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 24.1.0
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

scrollHorizontallyBy

added in version 22.1.0
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.

scrollVerticallyBy

added in version 22.1.0
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.

setMeasuredDimension

added in version 24.1.0
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 only called if a LayoutManager returns true from isAutoMeasureEnabled() and it is called after the RecyclerView calls onLayoutChildren(Recycler, State) in the execution of onMeasure(int, int).

This method must 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.

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.

setSpanCount

added in version 22.1.0
void setSpanCount (int spanCount)

Sets the number of spans to be laid out.

If getOrientation() is VERTICAL, this is the number of columns. If getOrientation() is HORIZONTAL, this is the number of rows.

Parameters
spanCount int: The total number of spans in the grid

See also:

setSpanSizeLookup

added in version 22.1.0
void setSpanSizeLookup (GridLayoutManager.SpanSizeLookup spanSizeLookup)

Sets the source to get the number of spans occupied by each item in the adapter.

Parameters
spanSizeLookup GridLayoutManager.SpanSizeLookup: GridLayoutManager.SpanSizeLookup instance to be used to query number of spans occupied by each item

setStackFromEnd

added in version 22.1.0
void setStackFromEnd (boolean stackFromEnd)

stackFromEnd is not supported by GridLayoutManager. Consider using setReverseLayout(boolean).

Parameters
stackFromEnd boolean

supportsPredictiveItemAnimations

added in version 22.1.0
boolean supportsPredictiveItemAnimations ()

Returns whether this LayoutManager supports "predictive item animations".

"Predictive item animations" are automatically created animations that show where items came from, and where they are going to, as items are added, removed, or moved within a layout.

A LayoutManager wishing to support predictive item animations must override this method to return true (the default implementation returns false) and must obey certain behavioral contracts outlined in onLayoutChildren(Recycler, State).

Whether item animations actually occur in a RecyclerView is actually determined by both 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 only "simple item animations" will be enabled in the RecyclerView, in which views whose position are changing are simply faded in/out. If the RecyclerView has a non-null ItemAnimator and this method returns true, then predictive item animations will be enabled in the RecyclerView.

Returns
boolean true if this LayoutManager supports predictive item animations, false otherwise.