RemDupFromList.java

RemDupFromList.java

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package java4s; import java.util.ArrayList; import java.util.HashSet; import java.util.Iterator; import java.util.List; public class RemDupFromList {     public static void main(String[] args)     {         List li = new ArrayList();               li.add("one");               li.add("two");               li.add("three");               li.add("one");//Duplicate               li.add("one");//Duplicate              // We have facility to pass a List into Set constructor and vice verse to cast                      List li2 = new ArrayList(new HashSet(li)); //no order              // List li2 = new ArrayList(new LinkedHashSet(li)); //If you need to preserve the order use 'LinkedHashSet'              Iterator it= li2.iterator();              while(it.hasNext())              {                  System.out.println(it.next());              }     } } Explanation Take your normal List object Pass that List li object to Set [Line number 22]  => So finally we have Set object in our hand, just pass this current Set object as argument to ArrayList, so we got new List object li2 without duplicate But if you would like to preserve the order of data use LinkedHashSet rather HashSet