Java removes duplicate elements from list

If set is used, if the element inside the list is not a basic data type but an object,

Then overwrite the boolean equals (object obj) and int hashcode () methods of object.

return new ArrayList (new HashSet (list));

method One : Looping elements delete  
//  Delete duplicate element   in ArrayList;

public static void 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);       }        }     }     system.out.println (list);} 

Method two : through HashSet culling
//  Delete duplicate element   in ArrayList;

public static void Removeduplicate (List list) {HashSet h = new HashSet (list);      List.clear ();      List.addall (h); SYSTEM.OUT.PRINTLN (list);}

Method Three : Delete duplicate elements in ArrayList, keep order
Delete duplicate elements in ArrayList, keep order

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);} 

If you are using HashSet, if you are an object, implement the Equals and Hashcode methods for the object.

Java removes duplicate elements from list