Question

I have a list that contain elements, I want to remove the duplicates. I have tried to do that but it didn’t work.

This is the code :

//list is the original list containing duplicates
Iterator it1=list.iterator();//iterator1 
 while (it1.hasNext())
  {
    Iterator it2=list.iterator(); //iterator2
    if(it1.next().equals(it2.next()))
     {
       //liststeps is the list without duplicates
       liststeps.add(it1.next());
     }
  } 
System.out.println("multiple list  "+list.toString());
System.out.println("list  "+liststeps.toString()); 

Results:

multiple list  [Open, In Progress, Waiting Customer Test, Closed, Open, Step11, Step22,  Open, In Progress, Waiting Customer Test, Closed]
list  [In Progress, Step11, In Progress]

Answer 1

Simply construct a HashSet or a TreeSet from your list:

Set<String> s = new HashSet<String>(list);

This will remove the duplicates, but will likely re-order the elements. If you want to preserve the order in which the (unique) elements appear in the original list, use LinkedHashSet:

Set<String> s = new LinkedHashSet<String>(list);

Lastly, if you need the output to be a list, convert the set to a list like so:

List<String> out = new ArrayList<String>(s);