非递归快速构建树

@Data
public class TreeNode {

    /**
     * 节点id
     */
    private String id;

    /**
     * 节点名称
     */
    private String name;

    /**
     * 层级
     */
    private int level;

    /**
     *  父节点id
     */
    private String parentId;

    /**
     * 子节点
     */
    private List<TreeNode> children = new ArrayList<>();

    public TreeNode() {}

    public TreeNode(String id, String parentId, String name) {
        this.id = id;
        this.name = name;
        this.parentId = parentId;
    }

    public TreeNode(String id, String name, int level, String parentId) {
        this.id = id;
        this.name = name;
        this.level = level;
        this.parentId = parentId;
    }

    public void addChild(TreeNode node) {
        this.children.add(node);
    }

}

public class TreeNodeUtil {

    public static List<TreeNode> buildTree(List<TreeNode> orginals){
        // 创建Map,把所有原始数据的ID作为Key,原始数据对象作为VALUE
        Map<String, TreeNode> dataMap = new LinkedHashMap<>();
        for (TreeNode node : orginals) {
            dataMap.put(node.getId(), node);
        }
        List<TreeNode> result = new ArrayList<>();
        for (Map.Entry<String, TreeNode> entry : dataMap.entrySet()) {
            TreeNode node = entry.getValue();
            if (node.getParentId().equals("0")) {
                // 如果是顶层节点，直接添加到结果集合中
                result.add(node);
            } else {
                // 如果不是顶层节点，找到父节点，然后添加到父节点的子节点中
                if (dataMap.get(node.getParentId()) != null) {
                    dataMap.get(node.getParentId()).addChild(node);
                }
            }
        }
        return result;
    }

    public static void main(String[] args) {
        List<TreeNode> orginals = new ArrayList<>();
        for (int i = 1; i <= 1000; i++) {
            orginals.add(new TreeNode(i+"", "0", "name" + i));
        }
        for (int i = 1001; i <= 2000; i++) {
            orginals.add(new TreeNode(i+"", "1", "name" + i));
        }
        for (int i = 2001; i <= 3000; i++) {
            orginals.add(new TreeNode(i+"", "1001", "name" + i));
        }
        for (int i = 3001; i <= 4000; i++) {
            orginals.add(new TreeNode(i+"", "2001", "name" + i));
        }
        for (int i = 4001; i <= 5000; i++) {
            orginals.add(new TreeNode(i+"", "3001", "name" + i));
        }
        for (int i = 5001; i <= 6000; i++) {
            orginals.add(new TreeNode(i+"", "4001", "name" + i));
        }
        long start = System.currentTimeMillis();
        System.out.println("数据大小："+orginals.size());
        List<TreeNode> treeNodes = TreeNodeUtil.buildTree(orginals);
//        System.out.println(JSONUtil.toJsonStr(treeNodes));
        System.out.println("耗时："+(System.currentTimeMillis() - start));
    }

}