java使用平面文件中的父id创建多个树状结构

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.*;

public class TreeBuilder {
    public static void main(String[] args) {
        // 读取平面文件
        List<String> lines = readFile("data.txt");

        // 解析数据并构建节点对象
        Map<String, Node> nodes = parseData(lines);

        // 构建树状结构
        List<Node> roots = buildTree(nodes);

        // 遍历树状结构
        for (Node root : roots) {
            traverseTree(root, 0);
        }
    }

    // 读取平面文件
    private static List<String> readFile(String filePath) {
        List<String> lines = new ArrayList<>();
        try (BufferedReader reader = new BufferedReader(new FileReader(filePath))) {
            String line;
            while ((line = reader.readLine()) != null) {
                lines.add(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return lines;
    }

    // 解析数据并构建节点对象
    private static Map<String, Node> parseData(List<String> lines) {
        Map<String, Node> nodes = new HashMap<>();
        for (String line : lines) {
            String[] parts = line.split(",");
            String parentId = parts[0];
            String nodeId = parts[1];
            Node node = new Node(nodeId);
            nodes.put(nodeId, node);
            if (parentId.equals("0")) {
                // 根节点
                nodes.put(nodeId, node);
            } else {
                // 非根节点
                Node parent = nodes.get(parentId);
                parent.addChild(node);
            }
        }
        return nodes;
    }

    // 构建树状结构
    private static List<Node> buildTree(Map<String, Node> nodes) {
        List<Node> roots = new ArrayList<>();
        for (Node node : nodes.values()) {
            if (node.getParent() == null) {
                roots.add(node);
            }
        }
        return roots;
    }

    // 遍历树状结构
    private static void traverseTree(Node node, int depth) {
        StringBuilder indent = new StringBuilder();
        for (int i = 0; i < depth; i++) {
            indent.append("  ");
        }
        System.out.println(indent.toString() + node.getId());
        for (Node child : node.getChildren()) {
            traverseTree(child, depth + 1);
        }
    }

    // 节点类
    private static class Node {
        private String id;
        private Node parent;
        private List<Node> children;

        public Node(String id) {
            this.id = id;
            this.children = new ArrayList<>();
        }

        public String getId() {
            return id;
        }

        public Node getParent() {
            return parent;
        }

        public void setParent(Node parent) {
            this.parent = parent;
        }

        public List<Node> getChildren() {
            return children;
        }

        public void addChild(Node child) {
            child.setParent(this);
            children.add(child);
        }
    }
}