Java中List集合去除重复数据的方法

1. 循环list中的所有元素然后删除重复

 public   static   List  removeDuplicate(List list)  {
   for  ( int  i  =   0 ; i  <  list.size()  -   1 ; i ++ )  {
       for  ( int  j  =  list.size()  -   1 ; j  >  i; j -- )  {
            if  (list.get(j).equals(list.get(i)))  {
               list.remove(j);
             }
         }
       }
     return list;
 }

2. 通过HashSet踢除重复元素

 public static List removeDuplicate(List list) {
     HashSet h = new HashSet(list);
     list.clear();
     list.addAll(h);
     return list;
 }

3. 删除ArrayList中重复元素，保持顺序

 // 删除ArrayList中重复元素，保持顺序
  public static void removeDuplicateWithOrder(List list) {
     Set set = new HashSet();
      List newList = new ArrayList();
    for (Iterator iter = list.iterator(); iter.hasNext();) {
          Object element = iter.next();
          if (set.add(element))
             newList.add(element);
       }
      list.clear();
      list.addAll(newList);
     System.out.println( " remove duplicate " + list);
  }

4.把list里的对象遍历一遍，用list.contain()，如果不存在就放入到另外一个list集合中

 public static List removeDuplicate(List list){
         List listTemp = new ArrayList();
         for(int i=0;i<list.size();i++){
             if(!listTemp.contains(list.get(i))){
                 listTemp.add(list.get(i));
             }
         }
         return listTemp;
     }