コレクション内の重複する要素の除去

 1 class ArrayListTest1 {

 2     public static void main(String[] args) {

 3         ArrayList al = new ArrayList();

 4         al.add("java03");

 5         al.add("java03");

 6         al.add("java01");

 7         al.add("java02");

 8         al.add("java01");

 9         al.add("java02");

10         al.add("java01");

11         System.out.println(al);

12         

13         al = singleElement(al);

14         System.out.println(al);

15         

16     }

17 

18     // List 

19     public static ArrayList singleElement(ArrayList al){

20       // 

21       ArrayList newAl = new ArrayList();

22       // next ， hasNext 

23       Iterator it = al.iterator();

24         

25        while (it.hasNext()){

26          Object obj = it.next();//next() hasNext() 

27 

28          if (!newAl.contains(obj))

29             newAl.add(obj);

30         }

31         return newAl;

32     }

33 }