Builder

Kotlin |Java

class Builder<K : Any!>

kotlin.Any
↳	androidx.recyclerview.selection.SelectionTracker.Builder

Builder is the primary mechanism for create a SelectionTracker that can be used with your RecyclerView. Once installed, users will be able to create and manipulate selection using a variety of intuitive techniques like tap, gesture, and mouse lasso.

Example usage:

SelectionTracker<uri>
  tracker = new SelectionTracker.Builder&lt;&gt;(
             "my-uri-selection",
             recyclerView,
             new DemoStableIdProvider(recyclerView.getAdapter()),
             new MyDetailsLookup(recyclerView),
             StorageStrategy.createParcelableStorage(Uri.class))
             .build();
     
</uri>

Restricting which items can be selected and limiting selection size

SelectionPredicate provides a mechanism to restrict which Items can be selected, to limit the number of items that can be selected, as well as allowing the selection code to be placed into "single select" mode, which as the name indicates, constrains the selection size to a single item.

Configuring the tracker for single single selection support can be done by supplying SelectionPredicates#createSelectSingleAnything(). SelectionTracker tracker = new SelectionTracker.Builder<>( "my-string-selection", recyclerView, new DemoStableIdProvider(recyclerView.getAdapter()), new MyDetailsLookup(recyclerView), StorageStrategy.createStringStorage()) .withSelectionPredicate(SelectionPredicates#createSelectSingleAnything()) .build();

Retaining state across Android lifecycle events

Support for storage/persistence of selection must be configured and invoked manually owing to its reliance on Activity lifecycle events. Failure to include support for selection storage will result in the active selection being lost when the Activity receives a configuration change (e.g. rotation) or when the application process is destroyed by the OS to reclaim resources.

Key Type

Developers must decide on the key type used to identify selected items. Support is provided for three types: Parcelable, String, and Long.

Parcelable: Any Parcelable type can be used as the selection key. This is especially useful in conjunction with android.net.Uri as the Android URI implementation is both parcelable and makes for a natural stable selection key for values represented by the Android Content Provider framework. If items in your view are associated with stable content:// uris, you should use Uri for your key type.

String: Use String when a string based stable identifier is available.

Long: Use Long when RecyclerView's long stable ids are already in use. It comes with some limitations, however, as access to stable ids at runtime is limited. Band selection support is not available when using the default long key storage implementation. See StableIdKeyProvider for details.

Usage:

private SelectionTracker<uri>
  mTracker;
     
      public void onCreate(Bundle savedInstanceState) {
        // See above for details on constructing a SelectionTracker instance.
     
        if (savedInstanceState != null) {
           mTracker.onRestoreInstanceState(savedInstanceState);
        }
      }
     
      protected void onSaveInstanceState(Bundle outState) {
          super.onSaveInstanceState(outState);
          mTracker.onSaveInstanceState(outState);
      }
      
</uri>

Summary

Public constructors
<init>(@NonNull selectionId: String, @NonNull recyclerView: RecyclerView, @NonNull keyProvider: ItemKeyProvider<K>, @NonNull detailsLookup: ItemDetailsLookup<K>, @NonNull storage: StorageStrategy<K>) Creates a new SelectionTracker.

Public methods
SelectionTracker<K>!	build() Prepares and returns a SelectionTracker.
SelectionTracker.Builder<K>!	withBandOverlay(@DrawableRes bandOverlayId: Int) Replaces default band overlay.
SelectionTracker.Builder<K>!	withBandPredicate(@NonNull bandPredicate: BandPredicate) Replaces default band predicate.
SelectionTracker.Builder<K>!	withFocusDelegate(@NonNull delegate: FocusDelegate<K>) Add focus delegate to interact with selection related focus changes.
SelectionTracker.Builder<K>!	withGestureTooltypes(vararg toolTypes: Int) Replaces default tap and gesture tool-types.
SelectionTracker.Builder<K>!	withOnContextClickListener(@NonNull listener: OnContextClickListener) Adds a context click listener.
SelectionTracker.Builder<K>!	withOnDragInitiatedListener(@NonNull listener: OnDragInitiatedListener) Adds a drag initiated listener.
SelectionTracker.Builder<K>!	withOnItemActivatedListener(@NonNull listener: OnItemActivatedListener<K>) Adds an item activation listener.
SelectionTracker.Builder<K>!	withOperationMonitor(@NonNull monitor: OperationMonitor) Add operation monitor allowing access to information about active operations (like band selection and gesture selection).
SelectionTracker.Builder<K>!	withPointerTooltypes(vararg toolTypes: Int) Replaces default pointer tool-types.
SelectionTracker.Builder<K>!	withSelectionPredicate(@NonNull predicate: SelectionTracker.SelectionPredicate<K>) Install selection predicate.

Public constructors

<init>

Builder(@NonNull selectionId: String, @NonNull recyclerView: RecyclerView, @NonNull keyProvider: ItemKeyProvider<K>, @NonNull detailsLookup: ItemDetailsLookup<K>, @NonNull storage: StorageStrategy<K>)

Creates a new SelectionTracker.Builder useful for configuring and creating a new SelectionTracker for use with your RecyclerView.

Parameters
selectionId	String: A unique string identifying this selection in the context of the activity or fragment.
recyclerView	String: the owning RecyclerView
keyProvider	String: the source of selection keys
detailsLookup	String: the source of information about RecyclerView items.
storage	String: Strategy for type-safe storage of selection state in Bundle.

Public methods

build

fun build(): SelectionTracker<K>!

Prepares and returns a SelectionTracker.

Return
SelectionTracker<K>!: this

withBandOverlay

fun withBandOverlay(@DrawableRes bandOverlayId: Int): SelectionTracker.Builder<K>!

Replaces default band overlay.

Parameters
bandOverlayId	Int:

Return
SelectionTracker.Builder<K>!: this

withBandPredicate

fun withBandPredicate(@NonNull bandPredicate: BandPredicate): SelectionTracker.Builder<K>!

Replaces default band predicate.

Parameters
bandPredicate	BandPredicate:

Return
SelectionTracker.Builder<K>!: this

withFocusDelegate

fun withFocusDelegate(@NonNull delegate: FocusDelegate<K>): SelectionTracker.Builder<K>!

Add focus delegate to interact with selection related focus changes.

Parameters
delegate	FocusDelegate<K>: the delegate to be used

Return
SelectionTracker.Builder<K>!: this

withGestureTooltypes

fun withGestureTooltypes(vararg toolTypes: Int): SelectionTracker.Builder<K>!

Replaces default tap and gesture tool-types. Defaults are: MotionEvent#TOOL_TYPE_FINGER and MotionEvent#TOOL_TYPE_UNKNOWN.

Parameters
toolTypes	Int: the tool types to be used

Return
SelectionTracker.Builder<K>!: this

withOnContextClickListener

fun withOnContextClickListener(@NonNull listener: OnContextClickListener): SelectionTracker.Builder<K>!

Adds a context click listener. Respond to right-click.

Parameters
listener	OnContextClickListener: the listener to be used

Return
SelectionTracker.Builder<K>!: this

withOnDragInitiatedListener

fun withOnDragInitiatedListener(@NonNull listener: OnDragInitiatedListener): SelectionTracker.Builder<K>!

Adds a drag initiated listener. Add support for drag and drop.

Parameters
listener	OnDragInitiatedListener: the listener to be used

Return
SelectionTracker.Builder<K>!: this

withOnItemActivatedListener

fun withOnItemActivatedListener(@NonNull listener: OnItemActivatedListener<K>): SelectionTracker.Builder<K>!

Adds an item activation listener. Respond to taps/enter/double-click on items.

Parameters
listener	OnItemActivatedListener<K>: the listener to be used

Return
SelectionTracker.Builder<K>!: this

withOperationMonitor

fun withOperationMonitor(@NonNull monitor: OperationMonitor): SelectionTracker.Builder<K>!

Add operation monitor allowing access to information about active operations (like band selection and gesture selection).

Parameters
monitor	OperationMonitor: the monitor to be used

Return
SelectionTracker.Builder<K>!: this

withPointerTooltypes

fun withPointerTooltypes(vararg toolTypes: Int): SelectionTracker.Builder<K>!

Replaces default pointer tool-types. Pointer tools are associated with band selection, and certain drag and drop behaviors. Defaults are: MotionEvent#TOOL_TYPE_MOUSE.

Parameters
toolTypes	Int: the tool types to be used

Return
SelectionTracker.Builder<K>!: this

withSelectionPredicate

fun withSelectionPredicate(@NonNull predicate: SelectionTracker.SelectionPredicate<K>): SelectionTracker.Builder<K>!

Install selection predicate.

Parameters
predicate	SelectionTracker.SelectionPredicate<K>: the predicate to be used.

Return
SelectionTracker.Builder<K>!: this