res.getInt() returns 0 for NULL?

Just need a clarification. When using res.getInt() on a column with a
null value I am getting back "0", should I not get some error thrown or
some kind or error instead?

The following code illustrates:

int id = res.getInt("id");
if (res.wasNull()) {
System.out.println("result was null");
}
System.out.println("id is " + id);

Output:

result was null
id is 0

Thanks,

Jc