List<list>进行去重排序-蒲公英云

List<list>进行去重排序

接到任务进行一个菜单去重排序的功能还是比较有意思的

背景：一个用户存在多个角色一个角色分别有对应的菜单所以要进行合并去重排序处理并且菜单拥有二级甚至三级菜单

先定义一个Menu类并且重写它的hashcode和equals

package com.sitech.smartcity.common.entity;
import java.util.List;
public class Menu {
   private String menuName;
   private String url;
   private List<Menu> menus;
   private String openType;//0:iframe嵌套  1： load加载 ；2 ：window.location打开新界面
   private String logourl;
   private String code;//app业务编码
   private String classCode;//分类编码
   private String appid;
   private Integer classPriority;//排序字段
   public Integer getClassPriority() {
      return classPriority;
   }
   public void setClassPriority(Integer classPriority) {
      this.classPriority = classPriority;
   }
   public String getMenuName() {
      return menuName;
   }
   public void setMenuName(String menuName) {
      this.menuName = menuName;
   }
   public String getUrl() {
      return url;
   }
   public void setUrl(String url) {
      this.url = url;
   }
   public List<Menu> getMenus() {
      return menus;
   }
   public void setMenus(List<Menu> menus) {
      this.menus = menus;
   }
   public String getOpenType() {
      return openType;
   }
   public void setOpenType(String openType) {
      this.openType = openType;
   }
   public String getLogourl() {
      return logourl;
   }
   public void setLogourl(String logourl) {
      this.logourl = logourl;
   }
   public String getCode() {
      return code;
   }
   public void setCode(String code) {
      this.code = code;
   }
   public String getClassCode() {
      return classCode;
   }
   public void setClassCode(String classCode) {
      this.classCode = classCode;
   }
   public String getAppid() {
      return appid;
   }
   public void setAppid(String appid) {
      this.appid = appid;
   }
   @Override
   public boolean equals(Object o) {
      if (this == o) return true;
      if (o == null || getClass() != o.getClass()) return false;
      Menu menu = (Menu) o;
      if (menuName != null ? !menuName.equals(menu.menuName) : menu.menuName != null) return false;
      if (url != null ? !url.equals(menu.url) : menu.url != null) return false;
      if (openType != null ? !openType.equals(menu.openType) : menu.openType != null) return false;
      if (code != null ? !code.equals(menu.code) : menu.code != null) return false;
      if (classCode != null ? !classCode.equals(menu.classCode) : menu.classCode != null) return false;
      if (appid != null ? !appid.equals(menu.appid) : menu.appid != null) return false;
      return classPriority != null ? classPriority.equals(menu.classPriority) : menu.classPriority == null;
   }
   @Override
   public int hashCode() {
      int result = menuName != null ? menuName.hashCode() : 0;
      result = 31 * result + (url != null ? url.hashCode() : 0);
      result = 31 * result + (menus != null ? menus.hashCode() : 0);
      result = 31 * result + (openType != null ? openType.hashCode() : 0);
      result = 31 * result + (logourl != null ? logourl.hashCode() : 0);
      result = 31 * result + (code != null ? code.hashCode() : 0);
      result = 31 * result + (classCode != null ? classCode.hashCode() : 0);
      result = 31 * result + (appid != null ? appid.hashCode() : 0);
      result = 31 * result + (classPriority != null ? classPriority.hashCode() : 0);
      return result;
   }
}

然后写几个方法用来合并去重排序的方法

//清除重复数据 利用set集合的 无重复特点 
public static List removeDuplicate(List list) {
   HashSet h = new HashSet(list);
   list.clear();
   list.addAll(h);
   return list;
}
//根据排序字段进行排序
public static List compareList(List<Menu> list){
   Collections.sort(list, new Comparator<Menu>() {
      @Override
      public int compare(Menu m1,Menu m2) {
         if (m1.getClassPriority() > m2.getClassPriority()) {
            return 1;
         }
         if (m1.getClassPriority() == m2.getClassPriority()) {
            return 0;
         }
         return -1;
      }
   });
   return list;
}
//递归  合并  去重
public static void trecursive(List<Menu> list){
   try {
      for(Iterator<Menu> oneIter = list.iterator(); oneIter.hasNext();){
         Menu one = oneIter.next();
         for(Iterator<Menu> twoIter = list.iterator(); twoIter.hasNext();){
            Menu two = twoIter.next();
            //classcode为菜单的唯一标识  此处使用刚才重写的equals比较两个Menu对象也可
            if(one.getClassCode()!=null&&one.getClassCode().equals(two.getClassCode())){
               //如果进入 说明存在两个相同菜单  子菜单为空的情况  填充菜单  再去重
               if (one.getMenus() == null && two.getMenus() != null) {
                  one.setMenus(two.getMenus());
               }
               if (two.getMenus() == null && one.getMenus() != null) {
                  two.setMenus(one.getMenus());
               }
               if (two.getMenus() == null && one.getMenus() == null) {
                  continue;
               }
               //否则合并  去重被合并菜单
               one.getMenus().addAll(two.getMenus());
               two.setMenus(one.getMenus());
               removeDuplicate(one.getMenus());
               compareList(one.getMenus());
               //递归
               trecursive(one.getMenus());
            }
         }
      }
   }catch (Exception e){
      e.printStackTrace();
   }
}