java已知父子关系构建组织菜单层级或者树状结构简单for代码实现

java已知父子关系构建组织菜单层级或者树状结构简单for代码实现

事情是这样的：看到相关技术推文感觉不符合实际而写。
推文地址：https://mp.weixin.qq.com/s/bgdjnFPKkKqOyKx20oSFgQ

for循环版：

import com.alibaba.fastjson.JSON;
import lombok.Data;
import org.junit.Test;

import java.util.ArrayList;
import java.util.List;
import java.util.Objects;

public class hisTest {

    @Data
    public class Menu {
        /**
         * id
         */
        public Integer id;
        /**
         * 名称
         */
        public String name;
        /**
         * 父id ，根节点为0
         */
        public Integer parentId;
        /**
         * 子节点信息
         */
        public List<Menu> childList;

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

    }

    @Test
    public void treeHandle() {
        //模拟从数据库一次性查询出所有组织菜单或者层级数据等
        List<Menu> menus = new ArrayList<>();
        menus.add(new Menu(1, "根节点", 0));
        menus.add(new Menu(2, "子节点1", 1));
        menus.add(new Menu(3, "子节点1.1", 2));
        menus.add(new Menu(4, "子节点1.2", 2));
        menus.add(new Menu(5, "根节点1.3", 2));
        menus.add(new Menu(6, "根节点2", 1));
        menus.add(new Menu(7, "根节点2.1", 6));
        menus.add(new Menu(8, "根节点2.2", 6));
        menus.add(new Menu(9, "根节点2.2.1", 7));
        menus.add(new Menu(10, "根节点2.2.2", 7));
        menus.add(new Menu(11, "根节点3", 1));
        menus.add(new Menu(12, "根节点3.1", 11));

        //临时存储子节点数据
        List<Menu> temp = new ArrayList<>();
        for (Menu menu : menus) {
            //子节点数据
            List<Menu> childList = new ArrayList<>();
            for (Menu childMenu : menus) {
                if (Objects.equals(menu.id, childMenu.getParentId())) {
                    childList.add(childMenu);
                    temp.add(childMenu);
                }
            }
            menu.setChildList(childList);
        }
        //原数据集合移除子节点
        if (temp.size() > 0) {
            menus.removeAll(temp);
        }
        System.out.println("-------转json输出结果-------");
        System.out.println(JSON.toJSON(menus));

    }
}

结果：

[{
	"name": "根节点",
	"childList": [{
		"name": "子节点1",
		"childList": [{
			"name": "子节点1.1",
			"childList": [],
			"id": 3,
			"parentId": 2
		}, {
			"name": "子节点1.2",
			"childList": [],
			"id": 4,
			"parentId": 2
		}, {
			"name": "根节点1.3",
			"childList": [],
			"id": 5,
			"parentId": 2
		}],
		"id": 2,
		"parentId": 1
	}, {
		"name": "根节点2",
		"childList": [{
			"name": "根节点2.1",
			"childList": [{
				"name": "根节点2.2.1",
				"childList": [],
				"id": 9,
				"parentId": 7
			}, {
				"name": "根节点2.2.2",
				"childList": [],
				"id": 10,
				"parentId": 7
			}],
			"id": 7,
			"parentId": 6
		}, {
			"name": "根节点2.2",
			"childList": [],
			"id": 8,
			"parentId": 6
		}],
		"id": 6,
		"parentId": 1
	}, {
		"name": "根节点3",
		"childList": [{
			"name": "根节点3.1",
			"childList": [],
			"id": 12,
			"parentId": 11
		}],
		"id": 11,
		"parentId": 1
	}],
	"id": 1,
	"parentId": 0
}]