android 多级列表

Android中多级列表可以通过RecyclerView嵌套实现。下面是一个简单的示例：

1. 创建外层RecyclerView的Adapter。

public class OuterAdapter extends RecyclerView.Adapter<OuterAdapter.ViewHolder> {
    private List<OuterModel> mData;

    public OuterAdapter(List<OuterModel> data) {
        mData = data;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_outer, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        OuterModel outerModel = mData.get(position);
        holder.txtTitle.setText(outerModel.getTitle());

        InnerAdapter innerAdapter = new InnerAdapter(outerModel.getInnerList());
        holder.recyclerView.setLayoutManager(new LinearLayoutManager(holder.recyclerView.getContext()));
        holder.recyclerView.setAdapter(innerAdapter);
    }

    @Override
    public int getItemCount() {
        return mData.size();
    }

    static class ViewHolder extends RecyclerView.ViewHolder {
        TextView txtTitle;
        RecyclerView recyclerView;

        ViewHolder(@NonNull View itemView) {
            super(itemView);
            txtTitle = itemView.findViewById(R.id.txt_title);
            recyclerView = itemView.findViewById(R.id.recycler_view);
        }
    }
}

2. 创建内层RecyclerView的Adapter。

public class InnerAdapter extends RecyclerView.Adapter<InnerAdapter.ViewHolder> {
    private List<InnerModel> mData;

    public InnerAdapter(List<InnerModel> data) {
        mData = data;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_inner, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        InnerModel innerModel = mData.get(position);
        holder.txtTitle.setText(innerModel.getTitle());
    }

    @Override
    public int getItemCount() {
        return mData.size();
    }

    static class ViewHolder extends RecyclerView.ViewHolder {
        TextView txtTitle;

        ViewHolder(@NonNull View itemView) {
            super(itemView);
            txtTitle = itemView.findViewById(R.id.txt_title);
        }
    }
}

3. 创建数据模型类。

public class OuterModel {
    private String title;
    private List<InnerModel> innerList;

    public OuterModel(String title, List<InnerModel> innerList) {
        this.title = title;
        this.innerList = innerList;
    }

    public String getTitle() {
        return title;
    }

    public List<InnerModel> getInnerList() {
        return innerList;
    }
}

public class InnerModel {
    private String title;

    public InnerModel(String title) {
        this.title = title;
    }

    public String getTitle() {
        return title;
    }
}

4. 创建布局文件。

item_outer.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <TextView
        android:id="@+id/txt_title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="18sp"
        android:textStyle="bold" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

item_inner.xml：

<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/txt_title"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:paddingLeft="20dp"
    android:textSize="16sp" />

5. 在Activity或Fragment中使用多级列表。

public class MultiLevelListActivity extends AppCompatActivity {
    private RecyclerView mRecyclerView;
    private OuterAdapter mAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_multi_level_list);

        List<OuterModel> data = new ArrayList<>();
        List<InnerModel> innerList1 = new ArrayList<>();
        innerList1.add(new InnerModel("Inner 1-1"));
        innerList1.add(new InnerModel("Inner 1-2"));
        data.add(new OuterModel("Outer 1", innerList1));

        List<InnerModel> innerList2 = new ArrayList<>();
        innerList2.add(new InnerModel("Inner 2-1"));
        innerList2.add(new InnerModel("Inner 2-2"));
        innerList2.add(new InnerModel("Inner 2-3"));
        data.add(new OuterModel("Outer 2", innerList2));

        List<InnerModel> innerList3 = new ArrayList<>();
        innerList3.add(new InnerModel("Inner 3-1"));
        data.add(new OuterModel("Outer 3", innerList3));

        mRecyclerView = findViewById(R.id.recycler_view);
        mAdapter = new OuterAdapter(data);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        mRecyclerView.setAdapter(mAdapter);
    }
}

以上就是一个简单的Android多级列表的实现方式。