定义 Menu
import lombok.AllArgsConstructor; import lombok.Data; import lombok.NoArgsConstructor; import lombok.experimental.Accessors; import java.util.List; /** * @ClassName Menu * @Description TODO * @Author YZJ * @Date 2022/11/27 20:31 **/ @Data @AllArgsConstructor @NoArgsConstructor @Accessors(chain = true) public class Menu { private Long id; //菜单名称 private String menuName; //父菜单ID private Long parentId; private List<Menu> children; }
生成树形结构
public static void main(String[] args) { Menu menu = new Menu(0L, "国家", -1L, null); Menu menu1 = new Menu(1L, "中国", 0L, null); Menu menu2 = new Menu(2L, "日本", 0L, null); Menu menu3 = new Menu(3L, "美国", 0L, null); Menu menu4 = new Menu(4L, "北京", 1L, null); Menu menu5 = new Menu(5L, "上海", 1L, null); Menu menu6 = new Menu(6L, "武汉", 1L, null); Menu menu7 = new Menu(7L, "东京", 2L, null); Menu menu8 = new Menu(8L, "大阪", 2L, null); Menu menu9 = new Menu(9L, "华盛顿", 3L, null); Menu menu10 = new Menu(10L, "纽约", 3L, null); Menu menu11 = new Menu(11L, "加州", 3L, null); Menu menu12 = new Menu(12L, "洪山区", 6L, null); Menu menu13 = new Menu(13L, "武昌区", 6L, null); Menu menu14 = new Menu(14L, "汉阳区", 6L, null); List<Menu> menus = new ArrayList<>(); menus.add(menu); menus.add(menu1); menus.add(menu2); menus.add(menu3); menus.add(menu4); menus.add(menu5); menus.add(menu6); menus.add(menu7); menus.add(menu8); menus.add(menu9); menus.add(menu10); menus.add(menu11); menus.add(menu12); menus.add(menu13); menus.add(menu14); // 从 0 开始构建整个树 long parentId = 0L; System.out.println(JSON.toJSONString(builderMenuTree(menus, parentId))); } private static List<Menu> builderMenuTree(List<Menu> menus, long parentId) { return menus.stream() .filter(menu -> menu.getParentId() != null && menu.getParentId().equals(parentId)) .map(menu -> menu.setChildren(getChildren(menu, menus))) .collect(Collectors.toList()); } private static List<Menu> getChildren(Menu menu, List<Menu> menus) { return menus.stream() .filter(m -> menu.getParentId() != null && m.getParentId().equals(menu.getId())) .map(m -> m.setChildren(getChildren(m,menus))) .collect(Collectors.toList()); }
输出
[ { "children":[ { "children":[ ], "id":4, "menuName":"北京", "parentId":1 }, { "children":[ ], "id":5, "menuName":"上海", "parentId":1 }, Object{...} ], "id":1, "menuName":"中国", "parentId":0 }, { "children":Array[2], "id":2, "menuName":"日本", "parentId":0 }, { "children":Array[3], "id":3, "menuName":"美国", "parentId":0 } ]
标签:遍历,Java,Menu,menus,add,树形,menu,new,null From: https://www.cnblogs.com/big-keyboard/p/17137633.html