Duplicate objects are added to the list [duplicate]

Answer 1

Your problem is that you're referencing the same object cause you created the object before the loop. Should be

public static void main(String args[]) {

    ArrayList al = new ArrayList();


    for (int i = 0; i < 10; i++) {
        Modelclass obj = new Modelclass();
        obj.setName(2 + i);
        obj.setRoolno(4 + i);
        System.out.println(obj);

        //if (!al.equals(obj)) {

            al.add(obj);
            System.out.println(obj.getName() + "" + obj.getRoolno());

        //}

    }
}