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;
    }