java examples
Home Java Examples Resources Java Interview Questions
Brainpower SEO

How to remove duplicate element from array?

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

package com.javacoderanch.example.util;

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 + ", ");
        }
    }
}