How to remove duplicate element from array?

This example demonstrates you how to remove duplicate elements from an array using the java.util.HashSet class.

import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public class ArrayRemoveDuplicate {

 public static void main(String[] args) {
  //
  // A string array with duplicate values
  //
  String[] data = { "A", "C", "B", "D", "A", "B", "E", "D", "B", "C" };
  System.out.println("Original array: " + Arrays.toString(data));

  //
  // Convert it to list as we need the list object to create a
  // set object. A set is a collection object that cannot have
  // a duplicate values, so by converting the array to a set
  // the duplicate value will be removed.
  //
  List< string > list = Arrays.asList(data);

  Set< string > set = new HashSet< string >(list);

  System.out.print("Remove duplicate result: ");

  //
  // Create an array to convert the Set back to array.
  // The Set.toArray() method copy the value in the set to the
  // defined array.
  //
  String[] result = new String[set.size()];
  set.toArray(result);
  for (String s : result) {
   System.out.print(s + ", ");
  }
 }
}

The output is:



Original array: [A, C, B, D, A, B, E, D, B, C]
Remove duplicate result: D, E, A, B, C,