JAVA递归-根据id获取所有相关联的id

淡淡的烟草味﹌ 2022-12-03 08:56 72阅读 0赞

import org.junit.Test;
    
    import java.util.ArrayList;
    import java.util.List;
    
    public class myTest {
        @Test
        public void t1() {
            Menu m = new Menu();
            m.setId(1);
            m.setpId(0);
            Menu m2 = new Menu();
            m2.setId(2);
            m2.setpId(1);
            Menu m3 = new Menu();
            m3.setId(3);
            m3.setpId(1);
            Menu m4 = new Menu();
            m4.setId(4);
            m4.setpId(1);
    
            List<Menu> list = new ArrayList<>();
            list.add(m);
            list.add(m2);
            list.add(m3);
            list.add(m4);
            List<String> ls = new ArrayList<>();
            ls.add("1");
            getIds(list, 1, ls);
            System.out.println("ls:" + ls);
            // 输出结果：
            // ls:[1, 2, 3, 4]
        }
    
        //封装递归方法
        private List<String> getIds(List<Menu> ms, int id, List<String> ids) {
            for (int i = 0; i < ms.size(); i++) {
                if (ms.get(i).getpId() == id) {
                    ids.add(String.valueOf(ms.get(i).getId()));
                    getIds(ms, ms.get(i).getId(), ids);
                }
            }
            return ids;
        }
    
        //pojo
        class Menu {
            private int id;
            private int pId;
    
            public int getId() {
                return id;
            }
    
            public void setId(int id) {
                this.id = id;
            }
    
            public int getpId() {
                return pId;
            }
    
            public void setpId(int pId) {
                this.pId = pId;
            }
        }
    }