LayoutManager

Kotlin |Java

abstract class LayoutManager

kotlin.Any
↳	androidx.recyclerview.widget.RecyclerView.LayoutManager

Known Direct Subclasses

LinearLayoutManager, StaggeredGridLayoutManager

LinearLayoutManager	A `RecyclerView.LayoutManager` implementation which provides similar functionality to `android.widget.ListView`.
StaggeredGridLayoutManager	A LayoutManager that lays out children in a staggered grid formation.

Known Indirect Subclasses

GridLayoutManager, WearableLinearLayoutManager

GridLayoutManager	A `RecyclerView.LayoutManager` implementations that lays out items in a grid.
WearableLinearLayoutManager	This wear-specific implementation of `LinearLayoutManager` provides basic offsetting logic for updating child layout.

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
abstract	`LayoutPrefetchRegistry` Interface for LayoutManagers to request items to be prefetched, based on position, with specified distance from viewport, which indicates priority.
open	`Properties` Some general properties that a LayoutManager may want to use.

Public constructors
`<init>()` 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.

Public methods
open Unit	`addDisappearingView(child: View!)` 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.
open Unit	`addDisappearingView(child: View!, index: Int)` 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.
open Unit	`addView(child: View!)` Add a view to the currently attached RecyclerView if needed.
open Unit	`addView(child: View!, index: Int)` Add a view to the currently attached RecyclerView if needed.
open Unit	`assertInLayoutOrScroll(message: String!)` Checks if RecyclerView is in the middle of a layout or scroll and throws an `IllegalStateException` if it is not.
open Unit	`assertNotInLayoutOrScroll(message: String!)` Checks if RecyclerView is in the middle of a layout or scroll and throws an `IllegalStateException` if it is.
open Unit	`attachView(@NonNull child: View, index: Int, lp: RecyclerView.LayoutParams!)` Reattach a previously `detached` view.
open Unit	`attachView(@NonNull child: View, index: Int)` Reattach a previously `detached` view.
open Unit	`attachView(@NonNull child: View)` Reattach a previously `detached` view.
open Unit	`calculateItemDecorationsForChild(@NonNull child: View, @NonNull outRect: Rect)` Calculates the item decor insets applied to the given child and updates the provided Rect instance with the inset values.
open Boolean	`canScrollHorizontally()` Query if horizontal scrolling is currently supported.
open Boolean	`canScrollVertically()` Query if vertical scrolling is currently supported.
open Boolean	`checkLayoutParams(lp: RecyclerView.LayoutParams!)` Determines the validity of the supplied LayoutParams object.
open static Int	`chooseSize(spec: Int, desired: Int, min: Int)` Chooses a size from the given specs and parameters that is closest to the desired size and also complies with the spec.
open Unit	`collectAdjacentPrefetchPositions(dx: Int, dy: Int, state: RecyclerView.State!, layoutPrefetchRegistry: RecyclerView.LayoutManager.LayoutPrefetchRegistry!)` Gather all positions from the LayoutManager to be prefetched, given specified momentum.
open Unit	`collectInitialPrefetchPositions(adapterItemCount: Int, layoutPrefetchRegistry: RecyclerView.LayoutManager.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.
open Int	`computeHorizontalScrollExtent(@NonNull state: RecyclerView.State)` Override this method if you want to support scroll bars.
open Int	`computeHorizontalScrollOffset(@NonNull state: RecyclerView.State)` Override this method if you want to support scroll bars.
open Int	`computeHorizontalScrollRange(@NonNull state: RecyclerView.State)` Override this method if you want to support scroll bars.
open Int	`computeVerticalScrollExtent(@NonNull state: RecyclerView.State)` Override this method if you want to support scroll bars.
open Int	`computeVerticalScrollOffset(@NonNull state: RecyclerView.State)` Override this method if you want to support scroll bars.
open Int	`computeVerticalScrollRange(@NonNull state: RecyclerView.State)` Override this method if you want to support scroll bars.
open Unit	`detachAndScrapAttachedViews(@NonNull recycler: RecyclerView.Recycler)` Temporarily detach and scrap all currently attached child views.
open Unit	`detachAndScrapView(@NonNull child: View, @NonNull recycler: RecyclerView.Recycler)` Detach a child view and add it to a `Recycler's` scrap heap.
open Unit	`detachAndScrapViewAt(index: Int, @NonNull recycler: RecyclerView.Recycler)` Detach a child view and add it to a `Recycler's` scrap heap.
open Unit	`detachView(@NonNull child: View)` Temporarily detach a child view.
open Unit	`detachViewAt(index: Int)` Temporarily detach a child view.
open Unit	`endAnimation(view: View!)` Ends all animations on the view created by the `ItemAnimator`.
open View?	`findContainingItemView(@NonNull 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.
open View?	`findViewByPosition(position: Int)` Finds the view which represents the given adapter position.
abstract RecyclerView.LayoutParams!	`generateDefaultLayoutParams()` Create a default `LayoutParams` object for a child of the RecyclerView.
open RecyclerView.LayoutParams!	`generateLayoutParams(lp: LayoutParams!)` Create a LayoutParams object suitable for this LayoutManager, copying relevant values from the supplied LayoutParams object if possible.
open RecyclerView.LayoutParams!	`generateLayoutParams(c: Context!, attrs: AttributeSet!)`