如何将一个list中的对象按照父子菜单包含关系展示?
示例代码:
实体类:
import lombok.*;
import java.util.List;
@Setter
@Getter
@ToString
@NoArgsConstructor
@AllArgsConstructor
public class Menu {
private int id;
private int parentId;
private String name;
private List<Menu> children;
public Menu(int id, int parentId, String name) {
this.id = id;
this.parentId = parentId;
this.name = name;
}
}
测试类:
import org.junit.Test;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class SimpleTest2 extends BaseTest{
@Test
public void testListToMap(){
List<Menu> menuList = new ArrayList<>();
menuList.add(new Menu(1,0,"后台管理"));
menuList.add(new Menu(2,1,"用户管理"));
menuList.add(new Menu(3,1,"角色管理"));
menuList.add(new Menu(4,1,"菜单管理"));
menuList.add(new Menu(5,0,"商品管理"));
menuList.add(new Menu(6,5,"商品查询"));
menuList.add(new Menu(7,5,"商品添加"));
Map<Integer,Menu> menus = new HashMap<>();
//获取一级菜单,这里是后台管理,商品管理添加到menus里
for(Menu menu: menuList){
//parentId = 0 代表父菜单
if(menu.getParentId() == 0){
menus.put(menu.getId(),menu);
}else{
continue;
}
}
// 加载二级菜单
for(Menu menu:menuList){
if(menu.getParentId() != 0 && menus.get(menu.getParentId()) != null){
//父节点
Menu parentNode = menus.get(menu.getParentId());
//子节点
Menu childNode = menu;
if(parentNode.getChildren() == null){
List<Menu> children = new ArrayList<>();
parentNode.setChildren(children);
}
parentNode.getChildren().add(childNode);
}
}
// 二级菜单加载完毕
// 迭代打印菜单
for(Integer id: menus.keySet()){
Menu menu = menus.get(id);
System.out.println(menu.getName());
if(menu.getChildren() != null){
for(Menu menu1: menu.getChildren()){
System.out.println("\t" + menu1.getName());
}
}
}
}
}