How to compare two integer object?

Integer i = new Integer(0);
Integer j = new Integer(0);
while(i <= j && j <= i && i !=j ){
    System.out.println(i);
}

Why does this while loop execute? I understand that i != j. But separately, both i <= j and j <= i returns true. Why? And doesn't that mean that i == j? In that case the while loop shouldn't execute even once. But it goes for an infinite loop. Why is this so?

While == can be performed between two references (and is, when both sides are Integer), <= can't - so the compiler unboxes. So, your code is equivalent to:

while (i.intValue() <= j.intValue() &&
       j.intValue() <= i.intValue() &&
       i != j)

Now when i and j refer to different Integer objects with the same value, all of those conditions will be met - hence the loop keeps executing.

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