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

RecyclerView

public class RecyclerView
extends ViewGroup implements ScrollingView, NestedScrollingChild2

java.lang.Object
   ↳ android.view.View
     ↳ android.view.ViewGroup
       ↳ android.support.v7.widget.RecyclerView
Known Direct Subclasses
Known Indirect Subclasses


A flexible view for providing a limited window into a large data set.

Glossary of terms:

  • Adapter: A subclass of RecyclerView.Adapter responsible for providing views that represent items in a data set.
  • Position: The position of a data item within an Adapter.
  • Index: The index of an attached child view as used in a call to getChildAt(int). Contrast with Position.
  • Binding: The process of preparing a child view to display data corresponding to a position within the adapter.
  • Recycle (view): A view previously used to display data for a specific adapter position may be placed in a cache for later reuse to display the same type of data again later. This can drastically improve performance by skipping initial layout inflation or construction.
  • Scrap (view): A child view that has entered into a temporarily detached state during layout. Scrap views may be reused without becoming fully detached from the parent RecyclerView, either unmodified if no rebinding is required or modified by the adapter if the view was considered dirty.
  • Dirty (view): A child view that must be rebound by the adapter before being displayed.

Positions in RecyclerView:

RecyclerView introduces an additional level of abstraction between the RecyclerView.Adapter and RecyclerView.LayoutManager to be able to detect data set changes in batches during a layout calculation. This saves LayoutManager from tracking adapter changes to calculate animations. It also helps with performance because all view bindings happen at the same time and unnecessary bindings are avoided.

For this reason, there are two types of position related methods in RecyclerView:

  • layout position: Position of an item in the latest layout calculation. This is the position from the LayoutManager's perspective.
  • adapter position: Position of an item in the adapter. This is the position from the Adapter's perspective.

These two positions are the same except the time between dispatching adapter.notify* events and calculating the updated layout.

Methods that return or receive *LayoutPosition* use position as of the latest layout calculation (e.g. getLayoutPosition(), findViewHolderForLayoutPosition(int)). These positions include all changes until the last layout calculation. You can rely on these positions to be consistent with what user is currently seeing on the screen. For example, if you have a list of items on the screen and user asks for the 5th element, you should use these methods as they'll match what user is seeing.

The other set of position related methods are in the form of *AdapterPosition*. (e.g. getAdapterPosition(), findViewHolderForAdapterPosition(int)) You should use these methods when you need to work with up-to-date adapter positions even if they may not have been reflected to layout yet. For example, if you want to access the item in the adapter on a ViewHolder click, you should use getAdapterPosition(). Beware that these methods may not be able to calculate adapter positions if notifyDataSetChanged() has been called and new layout has not yet been calculated. For this reasons, you should carefully handle NO_POSITION or null results from these methods.

When writing a RecyclerView.LayoutManager you almost always want to use layout positions whereas when writing an RecyclerView.Adapter, you probably want to use adapter positions.

Summary

Nested classes

class RecyclerView.Adapter<VH extends RecyclerView.ViewHolder>

Base class for an Adapter

Adapters provide a binding from an app-specific data set to views that are displayed within a RecyclerView

class RecyclerView.AdapterDataObserver

Observer base class for watching changes to an RecyclerView.Adapter

interface RecyclerView.ChildDrawingOrderCallback

A callback interface that can be used to alter the drawing order of RecyclerView children. 

class RecyclerView.EdgeEffectFactory

EdgeEffectFactory lets you customize the over-scroll edge effect for RecyclerViews. 

class RecyclerView.ItemAnimator

This class defines the animations that take place on items as changes are made to the adapter. 

class RecyclerView.ItemDecoration

An ItemDecoration allows the application to add a special drawing and layout offset to specific item views from the adapter's data set. 

class RecyclerView.LayoutManager

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. 

class RecyclerView.LayoutParams

LayoutParams subclass for children of RecyclerView

interface RecyclerView.OnChildAttachStateChangeListener

A Listener interface that can be attached to a RecylcerView to get notified whenever a ViewHolder is attached to or detached from RecyclerView. 

class RecyclerView.OnFlingListener

This class defines the behavior of fling if the developer wishes to handle it. 

interface RecyclerView.OnItemTouchListener

An OnItemTouchListener allows the application to intercept touch events in progress at the view hierarchy level of the RecyclerView before those touch events are considered for RecyclerView's own scrolling behavior. 

class RecyclerView.OnScrollListener

An OnScrollListener can be added to a RecyclerView to receive messages when a scrolling event has occurred on that RecyclerView. 

class RecyclerView.RecycledViewPool

RecycledViewPool lets you share Views between multiple RecyclerViews. 

class RecyclerView.Recycler

A Recycler is responsible for managing scrapped or detached item views for reuse. 

interface RecyclerView.RecyclerListener

A RecyclerListener can be set on a RecyclerView to receive messages whenever a view is recycled. 

class RecyclerView.SimpleOnItemTouchListener

An implementation of RecyclerView.OnItemTouchListener that has empty method bodies and default return values. 

class RecyclerView.SmoothScroller

Base class for smooth scrolling. 

class RecyclerView.State

Contains useful information about the current RecyclerView state like target scroll position or view focus. 

class RecyclerView.ViewCacheExtension

ViewCacheExtension is a helper class to provide an additional layer of view caching that can be controlled by the developer. 

class RecyclerView.ViewHolder

A ViewHolder describes an item view and metadata about its place within the RecyclerView. 

XML attributes

RecyclerView_layoutManager  

Constants

int HORIZONTAL

int INVALID_TYPE

long NO_ID

int NO_POSITION

int SCROLL_STATE_DRAGGING

The RecyclerView is currently being dragged by outside input such as user touch input.

int SCROLL_STATE_IDLE

The RecyclerView is not currently scrolling.

int SCROLL_STATE_SETTLING

The RecyclerView is currently animating to a final position while not under outside control.

int TOUCH_SLOP_DEFAULT

Constant for use with setScrollingTouchSlop(int).

int TOUCH_SLOP_PAGING

Constant for use with setScrollingTouchSlop(int).

int VERTICAL

Inherited constants

From class android.view.ViewGroup
From class android.view.View