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; }
0

3 Answers

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

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.

2

EDIT: I just removed the unnecessary if statements and simplified them to make your code more readable.
Then I have replaced the set functions with the add function, because the set only can set existing elements.

EDIT2: Based on Andy Turner's answer, I modified my code. Thank you for the suggestions!

After these modifications, the code should look like this (add/remove/modify it for your needs):

public Collection<AdDistribution> getAdDistribution(byte srch, byte cont) throws IndexOutOfBoundsException { List<AdDistribution> mediums = new ArrayList<>(); if( ( srch == 0 && cont == 0 ) || srch == 1 ) { mediums.add(AdDistribution.SEARCH); } if( cont == 1 ) { mediums.add(AdDistribution.CONTENT); } return mediums; }
2