Java program to remove duplicates in an array

    Array is a collection of similar data types. But an element in the array may be repeated. Let us remove the duplicate elements in the array.

It has two types of implementation.

1. ·       Using Hash Set method.
2. ·       Using stream method.

Each method is coated with an example.

1.Using Hash Set method:

              This method used “Hash Set”. The steps to implement the method is given below.

• ·       First, include the built in packages java.util.Arrays and java.util.HashSet.
• ·       Create a class with main() function.
• ·       A integer array  a is declared and assigned with elements.
• ·       The original array is printed.
• ·       First, the hash set object is developed.
• ·       Using a for loop, hash set gets assigned with array values.
• ·       A new array is created with the hash set size.
• ·       Each element in the array and hash set is checked. If any duplicate occurs, it is deleted.
• ·       Finally, the array with no duplicate is displayed.

Program:

import java.util.Arrays;

import java.util.HashSet;

public class RemoveDuplicatesEg {

    public static void main(String[] args) {

        int[] a = {110, 220, 220, 83, 40, 110, 50, 83};

         System.out.println("The original elements are :" + Arrays.toString(a));

        // let us remove duplicates by Converting array to HashSet

        HashSet<Integer> set1 = new HashSet<>();

        for (int no : a) {

            set1.add(no);

        }

        // Let us retain the hashset to array

        int[] uArray = new int[set1.size()];

        int index = 0;

        for (int no : set1) {

            uArray[index++] = no;

        }

        System.out.println("The elements of Array without duplicates: " + Arrays.toString(uArray));

    }

}

Output:

C:\raji\blog>javac RemoveDuplicatesEg.java

C:\raji\blog>java RemoveDuplicatesEg

The original elements are :[110, 220, 220, 83, 40, 110, 50, 83]

The elements of Array without duplicates: [50, 83, 40, 220, 110]

2. Using stream method:

              This method uses the built-in methods “stream(), distinct(), toArray()” to remove duplicates in the array.

Program:

import java.util.Arrays;

import java.util.stream.IntStream;

public class RemoveDuplicatesStreamEg {

    public static void main(String[] args) {

        int[] a = {110, 23, 39, 23, 40, 110, 50, 39};

        System.out.println("The original elements are :" + Arrays.toString(a));

        int[] uArray = Arrays.stream(a)

                .distinct()

                .toArray();

        System.out.println("The elements in the array without duplicates: " + Arrays.toString(uArray));

    }

}

Output:

C:\raji\blog>javac RemoveDuplicatesStreamEg.java

C:\raji\blog>java RemoveDuplicatesStreamEg

The original elements are :[110, 23, 39, 23, 40, 110, 50, 39]

The elements in the array without duplicates: [110, 23, 39, 40, 50]

These are the ways to create the java program to remove the duplicates in the array. Hope these codes are useful to you. Keep coding!!!