Question

I’m debugging my code and it looks like the built-in function contains does not work properly in my case. Look:

List<Integer[]> allVariables = new ArrayList<Integer[]>();
Integer[] cols = {1};

The List contains values:

[0] = Integer[1] => {1}
[1] = Integer[4] => {1,2,3,4}

So, the following IF expression must be TRUE, but it’s false:

if (allVariables.contains(cols[0])) {
    //...
}

What’s the problem?

Answer 1

Contains is only going to look for the type that the list actually represents.

So if you have a list of Integer[], you are not going to be able to ever pass in an int and get a true result (since int cannot be null).

To do that you’d have to do a deep search yourself:

for(Integer[] arr : allVariables) {
    for(Integer i : arr) {
        if(i != null && i.equals(searchValue)) return true;
    }
}
return false;