Question

How can duplicate integers being added into an integer array be avoided without using any of the collections i.e. Arraylist or Set etc.?

Answer 1

If your problem is to return an Integer[], and not any other collection, you could however use a Set<Integer> privately to avoid duplicated values, and then return Set<Integer>.toArray(new Integer[0]).

That’s the simplest way IMHO…

For example:

private Set<Integer> intSet = new HashSet<Integer>();

public void setIntArray(Integer[] i){
    intSet = new HashSet<Integer>(Arrays.asList(i));
}

public Integer[] getIntArray(){
    return intSet.toArray(new Integer[0]);
}