java递归获取某个父节点下面的所有子节点

一.举个栗子

1.menu实体类

package com.dafy.insureagent.bean;
 
public class Menu {
	private String id;  
    private String name;  
    private String pid;
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getPid() {
		return pid;
	}
	public void setPid(String pid) {
		this.pid = pid;
	}
	@Override
	public String toString() {
		return "Menu [id=" + id + ", name=" + name + ", pid=" + pid + "]";
	}  
    
}

 

2.测试类

package com.dafy.insureagent.bean;
 
import java.util.ArrayList;
import java.util.List;
 
public class MenuRecursion {
	//子节点
	static List<Menu> childMenu = new ArrayList<Menu>();
 
	/**
	 * 获取某个父节点下面的所有子节点
	 * @param menuList
	 * @param pid
	 * @return
	 */
	public static List<Menu> treeMenuList(List<Menu> menuList, int pid) {
		for (Menu mu : menuList) {
			//遍历出父id等于参数的id，add进子节点集合
			if (Integer.valueOf(mu.getPid()) == pid) {
				//递归遍历下一级
				treeMenuList(menuList, Integer.valueOf(mu.getId()));
				childMenu.add(mu);
			}
		}
		return childMenu;
	}
	
	
 
	public static void main(String args[]) {
		List<Menu> menuList = new ArrayList<Menu>();
		Menu mu = new Menu();
		mu.setId("1");
		mu.setName("目录");
		mu.setPid("0");
		Menu mu1 = new Menu();
		mu1.setId("2");
		mu1.setName("目录1");
		mu1.setPid("1");
		Menu mu2 = new Menu();
		mu2.setId("3");
		mu2.setName("目录1.1");
		mu2.setPid("2");
		Menu mu3 = new Menu();
		mu3.setId("4");
		mu3.setName("目录1.2");
		mu3.setPid("2");
		Menu mu4 = new Menu();
		mu4.setId("5");
		mu4.setName("目录2");
		mu4.setPid("1");
		Menu mu5 = new Menu();
		mu5.setId("6");
		mu5.setName("目录2.1");
		mu5.setPid("5");
		Menu mu6 = new Menu();
		mu6.setId("7");
		mu6.setName("目录2.2");
		mu6.setPid("5");
		Menu mu7 = new Menu();
		mu7.setId("8");
		mu7.setName("目录2.2.1");
		mu7.setPid("7");
		menuList.add(mu);
		menuList.add(mu1);
		menuList.add(mu2);
		menuList.add(mu3);
		menuList.add(mu4);
		menuList.add(mu5);
		menuList.add(mu6);
		menuList.add(mu7);
 
		List<Menu> childList = treeMenuList(menuList, 1);
		for (Menu m : childList) {
			System.out.println(m.getId() + "   " + m.getName());
		}
	}
 
}

3.控制台结果(注:本身节点不会获取)： 

3   目录1.1
4   目录1.2
2   目录1
6   目录2.1
8   目录2.2.1
7   目录2.2
5   目录2

方便博主学习回忆

前面转载 https://blog.****.net/u010825931/article/details/79925719 

 如果想查A车间下面的最底层工位

 

再次遍历childlist是否是别人的父级，如果是，就不是最底层的

 List<Menu> childList = treeMenuList(List, pid);
                List<String > outList = new ArrayList<>();
                childList.forEach(data->{
                    List<Menu> modelList=List.stream().filter(fData->fData.getPid().equals(data.getId())).collect(Collectors.toList());
                    if(modelList.size()==0){
                        outList.add(data.getId());
                    }
                });