使用RecyclerView生成树形结构

以下是使用 RecyclerView 生成树形结构的示例代码，你可以根据自己的需求进行调整。

1. 定义数据模型：

public class TreeNode {
    private String name;
    private int id;
    private int parentId;
    private List<TreeNode> children;

    // 省略 getter 和 setter 方法
}

2. 创建适配器：

public class TreeAdapter extends RecyclerView.Adapter<TreeAdapter.ViewHolder> {
    private List<TreeNode> nodeList;

    public TreeAdapter(List<TreeNode> nodeList) {
        this.nodeList = nodeList;
    }

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

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        TreeNode node = nodeList.get(position);
        holder.nameTextView.setText(node.getName());
        holder.expandImageView.setImageResource(
                node.getChildren() != null && node.getChildren().size() > 0 ?
                        R.drawable.ic_expand : R.drawable.ic_collapse);
        holder.itemView.setOnClickListener(v -> {
            if (node.getChildren() != null && node.getChildren().size() > 0) {
                int index = holder.getAdapterPosition();
                if (nodeList.subList(index + 1, index + node.getChildren().size() + 1).isEmpty()) {
                    nodeList.addAll(index + 1, node.getChildren());
                    notifyItemRangeInserted(index + 1, node.getChildren().size());
                } else {
                    nodeList.removeAll(node.getChildren());
                    notifyItemRangeRemoved(index + 1, node.getChildren().size());
                }
                holder.expandImageView.setImageResource(
                        nodeList.get(index + 1).getChildren() != null &&
                                nodeList.get(index + 1).getChildren().size() > 0 ?
                                R.drawable.ic_expand : R.drawable.ic_collapse);
            }
        });
    }

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

    static class ViewHolder extends RecyclerView.ViewHolder {
        TextView nameTextView;
        ImageView expandImageView;

        ViewHolder(@NonNull View itemView) {
            super(itemView);
            nameTextView = itemView.findViewById(R.id.name);
            expandImageView = itemView.findViewById(R.id.expand);
        }
    }
}

3. 创建布局文件 item_node.xml：

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

    <ImageView
        android:id="@+id/expand"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_expand" />

    <TextView
        android:id="@+id/name"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:padding="8dp" />

</LinearLayout>

4. 在 Activity 或 Fragment 中使用 RecyclerView：

public class MainActivity extends AppCompatActivity {
    private RecyclerView recyclerView;
    private TreeAdapter treeAdapter;

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

        List<TreeNode> nodeList = createTree();
        treeAdapter = new TreeAdapter(nodeList);

        recyclerView = findViewById(R.id.recycler_view);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setAdapter(treeAdapter);
    }

    private List<TreeNode> createTree() {
        List<TreeNode> nodeList = new ArrayList<>();

        TreeNode root = new TreeNode();
        root.setName("Root");
        root.setId(0);
        root.setParentId(-1);

        TreeNode node1 = new TreeNode();
        node1.setName("Node 1");
        node1.setId(1);
        node1.setParentId(0);

        TreeNode node2 = new TreeNode();
        node2.setName("Node 2");
        node2.setId(2);
        node2.setParentId(0);

        TreeNode node11 = new TreeNode();
        node11.setName("Node 1.1");
        node11.setId(11);
        node11.setParentId(1);

        TreeNode node12 = new TreeNode();
        node12.setName("Node 1.2");
        node12.setId(12);
        node12.setParentId(1);

        TreeNode node21 = new TreeNode();
        node21.setName("Node 2.1");
        node21.setId(21);
        node21.setParentId(2);

        TreeNode node22 = new TreeNode();
        node22.setName("Node 2.2");
        node22.setId(22);
        node22.setParentId(2);

        node1.setChildren(Arrays.asList(node11, node12));
        node2.setChildren(Arrays.asList(node21, node22));
        root.setChildren(Arrays.asList(node1, node2));

        nodeList.add(root);

        return nodeList;
    }
}

以上代码实现了一个简单的树形结构，可以通过点击节点来展开或折叠其子节点列表。