在 Android 中使用 SelectionTracker 来选择所有项目的解决方法如下所示:
private SelectionTracker selectionTracker;
public MyAdapter() {
// ...
selectionTracker = new SelectionTracker.Builder<>(
"mySelection",
recyclerView,
new MyItemKeyProvider(),
new MyItemDetailsLookup(recyclerView),
StorageStrategy.createLongStorage())
.withSelectionPredicate(SelectionPredicates.createSelectAll())
.build();
}
public class MyItemKeyProvider extends ItemKeyProvider {
public MyItemKeyProvider() {
super(SCOPE_MAPPED);
}
@Nullable
@Override
public Long getKey(int position) {
// 返回项目在数据集中的唯一标识符
return getItem(position).getId();
}
@Override
public int getPosition(@NonNull Long key) {
// 返回项目在数据集中的位置
return getItemPosition(key);
}
}
public class MyItemDetailsLookup extends ItemDetailsLookup {
private RecyclerView recyclerView;
public MyItemDetailsLookup(RecyclerView recyclerView) {
this.recyclerView = recyclerView;
}
@Nullable
@Override
public ItemDetails getItemDetails(@NonNull MotionEvent e) {
// 获取点击位置的视图
View view = recyclerView.findChildViewUnder(e.getX(), e.getY());
if (view != null) {
// 获取项目的位置
int position = recyclerView.getChildAdapterPosition(view);
if (position != RecyclerView.NO_POSITION) {
// 获取项目的唯一标识符
long itemId = getItem(position).getId();
return new MyItemDetails(itemId, position);
}
}
return null;
}
}
public class MyItemDetails extends ItemDetailsLookup.ItemDetails {
private long itemId;
private int position;
public MyItemDetails(long itemId, int position) {
this.itemId = itemId;
this.position = position;
}
@Override
public int getPosition() {
return position;
}
@Nullable
@Override
public Long getSelectionKey() {
return itemId;
}
}
public class MyViewHolder extends RecyclerView.ViewHolder {
private TextView textView;
public MyViewHolder(View itemView) {
super(itemView);
textView = itemView.findViewById(R.id.text_view);
itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// 切换选择状态
selectionTracker.toggleSelection(getItemId());
}
});
}
public void bind(MyItem item) {
// 设置项目的文本
textView.setText(item.getText());
// 设置项目的选择状态
boolean isSelected = selectionTracker.isSelected(getItemId());
itemView.setActivated(isSelected);
}
}
public class MyAdapter extends RecyclerView.Adapter implements SelectionTracker.SelectionObserver {
// ...
@Override
public void onSelectionChanged() {
// 当选择状态发生变化时,更新 UI
Set selectedItems = selectionTracker.getSelection();
// ...
notifyDataSetChanged();
}
}
public class MyActivity extends AppCompatActivity {
private RecyclerView recyclerView;
private MyAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView = findViewById(R.id.recycler_view);
// 设置 RecyclerView 的布局管理器和适配器
recyclerView.setLayoutManager(new LinearLayoutManager(this));
adapter = new MyAdapter();
recyclerView.setAdapter(adapter);
// 启动 SelectionTracker
SelectionTracker selectionTracker = adapter.getSelectionTracker();
selectionTracker.addObserver(new SelectionTracker.SelectionObserver()