Introduction

We know ArrayList stores list of objects along with duplicates. In this article we are going to create our own custom ArrayList to stop allowing duplicates.

Steps

• Custom class should extends ArrayList class

• It should override add(T t) of ArrayList class

• We have to write our own logic to deny duplicates.

Code

import java.util.ArrayList;

public class CustomArrayList extends ArrayList<Integer>{

    @Override
    public boolean add(Integer e) {

        if(this.contains(e))
        {
            return true;
        }
        else
        {
            return super.add(e);
        }
    }

    public static void main(String[] args) {

        CustomArrayList c = new CustomArrayList();
        c.add(1);
        c.add(4);
        c.add(1);
        c.add(8);
        c.add(4);
        c.add(5);
        c.add(8);

        System.out.println(c);

    }
}

Output

[1, 4, 8, 5]

Thanks for reading :)

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