ArrayList<int[]> containing a value

Question

if i have an ArrayList<int[]> example and I want to check if {2,4} is in it how would I do this?

exaple.contains({2,4}); //doesn't work

and

exaple.contains(2,4); //doesn't work either

what is wrong with the code?

Answer 1

Arrays don't override the Object.equals() method (that ArrayList.contains() uses to compare objects). So an array is only equal to itself. You'll have to loop through the list and compare each element with your array using Arrays.equals().

What I suspect, though, is that you shouldn't have a List<int[]>, but a List<Coordinate>. The Coordinate class could then override equals() and hashCode(), and you would be able to use

example.contains(new Coordinate(2, 4))

You could also use a List<List<Integer>>, but if what I suspect is true (i.e. you're using arrays to hold two coordinates that should be in class), then go with the custom Coordinate class.