在Android开发中,使用androidx.recyclerview.selection库可以实现在回收视图(RecyclerView)中选择列出的所有项目。androidx.recyclerview.selection库提供了一种方便的方式来处理回收视图中的选择操作。
要使用androidx.recyclerview.selection选择回收视图中列出的所有项目,可以按照以下步骤进行操作:
implementation 'androidx.recyclerview:recyclerview-selection:1.1.0'
ItemKeyProvider
的选择器类,用于提供项目的唯一标识符。例如:public class MyItemKeyProvider extends ItemKeyProvider<Long> {
private List<MyItem> items;
public MyItemKeyProvider(List<MyItem> items) {
super(SCOPE_MAPPED);
this.items = items;
}
@Nullable
@Override
public Long getKey(int position) {
return items.get(position).getId();
}
@Override
public int getPosition(@NonNull Long key) {
for (int i = 0; i < items.size(); i++) {
if (items.get(i).getId().equals(key)) {
return i;
}
}
return RecyclerView.NO_POSITION;
}
}
SelectionTracker.SelectionObserver
的选择观察者类,用于监听选择操作的变化。例如:public class MySelectionObserver extends SelectionTracker.SelectionObserver<Long> {
@Override
public void onSelectionChanged() {
super.onSelectionChanged();
// 处理选择变化的逻辑
}
}
RecyclerView recyclerView = findViewById(R.id.recyclerView);
List<MyItem> items = ...; // 从数据源获取项目列表
MyItemKeyProvider itemKeyProvider = new MyItemKeyProvider(items);
SelectionTracker<Long> selectionTracker = new SelectionTracker.Builder<>(
"mySelection",
recyclerView,
itemKeyProvider,
new MyItemDetailsLookup(recyclerView),
StorageStrategy.createLongStorage()
).withSelectionPredicate(SelectionPredicates.createSelectAnything()).build();
MySelectionObserver selectionObserver = new MySelectionObserver();
selectionTracker.addObserver(selectionObserver);
ItemDetailsLookup
的类,用于提供项目的详细信息。例如:public class MyItemDetailsLookup extends ItemDetailsLookup<Long> {
private RecyclerView recyclerView;
public MyItemDetailsLookup(RecyclerView recyclerView) {
this.recyclerView = recyclerView;
}
@Nullable
@Override
public ItemDetails<Long> getItemDetails(@NonNull MotionEvent e) {
View view = recyclerView.findChildViewUnder(e.getX(), e.getY());
if (view != null) {
RecyclerView.ViewHolder viewHolder = recyclerView.getChildViewHolder(view);
if (viewHolder instanceof MyAdapter.MyViewHolder) {
return ((MyAdapter.MyViewHolder) viewHolder).getItemDetails();
}
}
return null;
}
}
RecyclerView.Adapter
的适配器类,并在其中处理选择状态的更新。例如:public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {
private List<MyItem> items;
private SelectionTracker<Long> selectionTracker;
public MyAdapter(List<MyItem> items, SelectionTracker<Long> selectionTracker) {
this.items = items;
this.selectionTracker = selectionTracker;
}
@NonNull
@Override
public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
// 创建ViewHolder
}
@Override
public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
// 绑定数据到ViewHolder
MyItem item = items.get(position);
holder.bind(item);
holder.itemView.setActivated(selectionTracker.isSelected(item.getId()));
}
@Override
public int getItemCount() {
return items.size();
}
public class MyViewHolder extends RecyclerView.ViewHolder {
private TextView textView;
public MyViewHolder(@NonNull View itemView) {
super(itemView);
textView = itemView.findViewById(R.id.textView);
}
public void bind(MyItem item) {
textView.setText(item.getName());
}
public ItemDetailsLookup.ItemDetails<Long> getItemDetails() {
return new ItemDetailsLookup.ItemDetails<Long>() {
@Override
public int getPosition() {
return getAdapterPosition();
}
@Nullable
@Override
public Long getSelectionKey() {
return items.get(getAdapterPosition()).getId();
}
};
}
}
}
MyAdapter adapter = new MyAdapter(items, selectionTracker);
recyclerView.setAdapter(adapter);
selectionTracker.attachToRecyclerView(recyclerView);
通过以上步骤,就可以实现在回收视图中选择列出的所有项目。你可以根据实际需求,自定义选择器、选择观察者、ItemDetailsLookup和适配器,以满足不同的选择需求。
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