java.lang.IndexOutOfBoundsException: Index: 0, Size: 0 exception [duplicate]

Question

I am getting the error java.lang.IndexOutOfBoundsException: Index: 0, Size: 0.

public Collection<AdDistribution> getAdDistribution(byte srch, byte cont) throws IndexOutOfBoundsException {

    List<AdDistribution> mediums = new ArrayList<>();
    List<AdDistribution> adDistribution = new ArrayList<>();
            adDistribution.add(AdDistribution.SEARCH);
            adDistribution.add(AdDistribution.CONTENT);
            if (adDistribution.isEmpty()) {
                return null;
              }

    if (srch == 0 && cont == 0) {
        mediums = new ArrayList<>();
        mediums.set(0, adDistribution.get(0));
    }
    if (srch == 1 || cont == 1) {
        mediums = new ArrayList<>();
        if (srch == 1) {
            mediums.set(0, adDistribution.get(0));
        } else if (cont == 1) {
            mediums.set(0, adDistribution.get(1));
        }
    }
    if (srch == 1 && cont == 1) {
        mediums = new ArrayList<>();
        mediums.set(0, adDistribution.get(0));
        mediums.set(1, adDistribution.get(1));
    }
            return mediums;
}

Answer 1

The problem is that you are using set method to update element at index 0

set(index,value) method needs an element to present at that index

but you haven't added any element at that position in medium arraylist before that .

So you need to first add an element at index 0 thereafter only you can update it with set method

Answer 2

You need to use

mediums.add(adDistribution.get(0));

rather than mediums.set(0, adDistribution.get(0)); etc.

ArrayList.set(int, Object) requires there to be an element to replace:

Replaces the element at the specified position in this list with the specified element.

Throws: IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size())

In a new list, size() == 0, so set(0, something) fails.