Question

Integer i = null;
if (i == 3)

Why the second line above throws a NullPointerException, IMHO, this has only one meaning which is Wrapper Object i is to be unboxed which yields the Exception such as:

ArrayList<Integer> list = new ArrayList<Integer>();
list.add(null);
int x = list.get(0);

EDIT: Can you supply me with some format doc?

Answer 1

It throws NPE because compiler does the following “magic” for you:

Integer i = null;
if (i.intValue() == 3)

Obviously i.intValue() throws NPE when i is null.