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RecyclerView.State

public static class RecyclerView.State
extends Object

java.lang.Object
↳	android.support.v7.widget.RecyclerView.State

Contains useful information about the current RecyclerView state like target scroll position or view focus. State object can also keep arbitrary data, identified by resource ids.

Often times, RecyclerView components will need to pass information between each other. To provide a well defined data bus between components, RecyclerView passes the same State object to component callbacks and these components can use it to exchange data.

If you implement custom components, you can use State's put/get/remove methods to pass data between your components without needing to manage their lifecycles.

Summary

Public constructors
`RecyclerView.State()`

Public methods
`boolean`	`didStructureChange()`
`<T> T`	`get(int resourceId)` Gets the Object mapped from the specified id, or `null` if no such data exists.
`int`	`getItemCount()` Returns the total number of items that can be laid out.
`int`	`getTargetScrollPosition()` If scroll is triggered to make a certain item visible, this value will return the adapter index of that item.
`boolean`	`hasTargetScrollPosition()` Returns if current scroll has a target position.
`boolean`	`isMeasuring()` Returns true if the RecyclerView is currently measuring the layout.
`boolean`	`isPreLayout()` Returns true if
`void`	`put(int resourceId, Object data)` Adds a mapping from the specified id to the specified value, replacing the previous mapping from the specified key if there was one.
`void`	`remove(int resourceId)` Removes the mapping from the specified id, if there was any.
`String`	`toString()` Returns a string representation of the object.
`boolean`	`willRunPredictiveAnimations()` Returns whether RecyclerView will run predictive animations in this layout pass or not.
`boolean`	`willRunSimpleAnimations()` Returns whether RecyclerView will run simple animations in this layout pass or not.

Inherited methods

From class


  
    java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long millis, int nanos)` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.
`final void`	`wait(long millis)` Causes the current thread to wait until either another thread invokes the `notify()` method or the `notifyAll()` method for this object, or a specified amount of time has elapsed.
`final void`	`wait()` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object.

Public constructors

RecyclerView.State

RecyclerView.State ()

Public methods

didStructureChange

boolean didStructureChange ()

Returns
`boolean`	true if the structure of the data set has changed since the last call to onLayoutChildren, false otherwise

get

T get (int resourceId)

Gets the Object mapped from the specified id, or null if no such data exists.

Parameters
`resourceId`	`int`: Id of the resource you want to remove. It is suggested to use R.id.* to preserve cross functionality and avoid conflicts.

Returns
`T`

getItemCount

int getItemCount ()

Returns the total number of items that can be laid out. Note that this number is not necessarily equal to the number of items in the adapter, so you should always use this number for your position calculations and never access the adapter directly.

RecyclerView listens for Adapter's notify events and calculates the effects of adapter data changes on existing Views. These calculations are used to decide which animations should be run.

To support predictive animations, RecyclerView may rewrite or reorder Adapter changes to present the correct state to LayoutManager in pre-layout pass.

For example, a newly added item is not included in pre-layout item count because pre-layout reflects the contents of the adapter before the item is added. Behind the scenes, RecyclerView offsets getViewForPosition(int) calls such that LayoutManager does not know about the new item's existence in pre-layout. The item will be available in second layout pass and will be included in the item count. Similar adjustments are made for moved and removed items as well.

You can get the adapter's item count via getItemCount() method.

Returns
`int`	The number of items currently available

See also:

getItemCount()

getTargetScrollPosition

int getTargetScrollPosition ()

If scroll is triggered to make a certain item visible, this value will return the adapter index of that item.

Returns
`int`	Adapter index of the target item or `NO_POSITION` if there is no target position.

hasTargetScrollPosition

boolean hasTargetScrollPosition ()

Returns if current scroll has a target position.

Returns
`boolean`	true if scroll is being triggered to make a certain position visible

See also:

getTargetScrollPosition()

isMeasuring

boolean isMeasuring ()

Returns true if the RecyclerView is currently measuring the layout. This value is true only if the LayoutManager opted into the auto measure API and RecyclerView has non-exact measurement specs.

Note that if the LayoutManager supports predictive animations and it is calculating the pre-layout step, this value will be false even if the RecyclerView is in onMeasure call. This is because pre-layout means the previous state of the RecyclerView and measurements made for that state cannot change the RecyclerView's size. LayoutManager is always guaranteed to receive another call to onLayoutChildren(Recycler, State) when this happens.

Returns
`boolean`	True if the RecyclerView is currently calculating its bounds, false otherwise.

isPreLayout

boolean isPreLayout ()

Returns true if

Returns
`boolean`

put

void put (int resourceId, 
                Object data)

Adds a mapping from the specified id to the specified value, replacing the previous mapping from the specified key if there was one.

Parameters
`resourceId`	`int`: Id of the resource you want to add. It is suggested to use R.id.* to preserve cross functionality and avoid conflicts.
`data`	`Object`: The data you want to associate with the resourceId.

remove

void remove (int resourceId)

Removes the mapping from the specified id, if there was any.

Parameters
`resourceId`	`int`: Id of the resource you want to remove. It is suggested to use R.id.* to preserve cross functionality and avoid conflicts.

toString

String toString ()

Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

 getClass().getName() + '@' + Integer.toHexString(hashCode())

Returns
`String`	a string representation of the object.

willRunPredictiveAnimations

boolean willRunPredictiveAnimations ()

Returns whether RecyclerView will run predictive animations in this layout pass or not.

Returns
`boolean`	true if RecyclerView is calculating predictive animations to be run at the end of the layout pass.

willRunSimpleAnimations

boolean willRunSimpleAnimations ()

Returns whether RecyclerView will run simple animations in this layout pass or not.

Returns
`boolean`	true if RecyclerView is calculating simple animations to be run at the end of the layout pass.

Annotations

Interfaces

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RecyclerView.State

Summary

Public constructors

Public methods

Inherited methods

Public constructors

RecyclerView.State

Public methods

didStructureChange

get

getItemCount

getTargetScrollPosition

hasTargetScrollPosition

isMeasuring

isPreLayout

put

remove

toString

willRunPredictiveAnimations

willRunSimpleAnimations