如何使用actionmode和selectiontracker实现全选按钮以选择recyclerview中的所有项目？答案

【问题标题】：How to implement select all button to select all items in recyclerview using actionmode and selectiontracker?如何使用actionmode和selectiontracker实现全选按钮以选择recyclerview中的所有项目？
【发布时间】：2021-03-17 13:34:56
【问题描述】：

我的 MainActivity 中有这段代码

    recyclerView.setAdapter(customAdapter);
    customAdapter.submitList(path_list);

    selectionTracker = new SelectionTracker.Builder<>(
            "my-selection-id",
            recyclerView,
            new ScrollKeyProvider(1, path_list),
            new ScrollItemDetailsLookup(recyclerView),
            StorageStrategy.createLongStorage()
    )
            .withOnItemActivatedListener(new OnItemActivatedListener<Long>() {
                @Override
                public boolean onItemActivated(@NonNull ItemDetailsLookup.ItemDetails<Long> item, @NonNull MotionEvent e) {
                    Log.d("TAG", "Selected ItemId: " + item.toString());
                    return true;
                }
            })
            .withOnDragInitiatedListener(new OnDragInitiatedListener() {
                @Override
                public boolean onDragInitiated(@NonNull MotionEvent e) {
                    Log.d("TAG", "onDragInitiated");
                    return true;
                }
            }).build();

    customAdapter.setSelectionTracker(selectionTracker);

    selectionTracker.addObserver(new SelectionTracker.SelectionObserver() {
        @Override
        public void onItemStateChanged(@NonNull Object key, boolean selected) {
            super.onItemStateChanged(key, selected);
        }

        @Override
        public void onSelectionRefresh() {
            super.onSelectionRefresh();
        }

        @Override
        public void onSelectionChanged() {
            super.onSelectionChanged();
            if (selectionTracker.hasSelection() && actionMode == null) {
                actionMode = startSupportActionMode(new ActionModeController(ScrollActivity.this, selectionTracker));
                actionMode.getMenu().findItem(R.id.action_item_count).setTitle("" + selectionTracker.getSelection().size());
            } else if (!selectionTracker.hasSelection() && actionMode != null) {
                actionMode.finish();
                actionMode = null;
            } else {
                actionMode.getMenu().findItem(R.id.action_item_count).setTitle("" + selectionTracker.getSelection().size());
            }
            Iterator<String> itemIterable = selectionTracker.getSelection().iterator();
            while (itemIterable.hasNext()) {
                Log.i("TAG", itemIterable.next());
            }
        }

        @Override
        public void onSelectionRestored() {
            super.onSelectionRestored();
        }
    });

这是我的 ActionMode 回调代码

public class ActionModeController implements ActionMode.Callback {

private final Context context;
private final SelectionTracker selectionTracker;

public ActionModeController(Context context, SelectionTracker selectionTracker) {
    this.context = context;
    this.selectionTracker = selectionTracker;
}

@Override
public boolean onCreateActionMode(androidx.appcompat.view.ActionMode mode, Menu menu) {
    mode.getMenuInflater().inflate(R.menu.action_menu, menu);
    return true;
}

@Override
public boolean onPrepareActionMode(androidx.appcompat.view.ActionMode mode, Menu menu) {
    return false;
}

@Override
public boolean onActionItemClicked(androidx.appcompat.view.ActionMode mode, MenuItem item) {
    if(item.getItemId()==R.id.action_clear){
        if (selectionTracker.hasSelection()){
            selectionTracker.clearSelection();
        }
    }
    else if(item.getItemId()==R.id.action_select_all){
       // **THIS IS PLACE WHERE I NEED HELP TO ENTER CODE FOR SELECT ALL FUNCTIONALITY**
    }
    return false;
}

@Override
public void onDestroyActionMode(androidx.appcompat.view.ActionMode mode) {
    selectionTracker.clearSelection();
}

}

在使用 SelectionTracker 选择 Recyclerview 中的所有项目时，我应该在 onActionItemClicked 中选择所有部分做什么？

你可以看到onActionItemClicked中的清除选项，我使用了selectionTracker的功能来清除所有选中的项目。我也期待选择所有选项的类似解决方案。

【问题讨论】：

标签： android android-studio android-recyclerview selection android-actionmode

【解决方案1】：

使用 PagingDataAdapter 的 Kotlin 版本 - 可以重新设计，将快照替换为您的实现中的项目。

                    var itemsArray = arrayListOf<Long>()
                    adapter?.snapshot()?.items?.forEach {
                        if (!selectionTracker.isSelected(it.id.toLong()))
                            itemsArray.add(it.id.toLong())
                    }
                    selectionTracker?.setItemsSelected(itemsArray.asIterable(), true)

【讨论】：