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;  
}