Java HashSet remove(e) method doesn't behave as I expected

collections, java

Solution

The problem is that in the first case, the expression `i` is of type `short`, whereas the expression `i - 1` is of type `int`. Those values are being boxed to `Short` and `Integer` respectively - the `Integer` isn't in the set, so can't be removed.

You can fix this with a cast:

for (short i = 0; i < 3; i++) {
    shortSet.add(i);
    shortSet.remove((short) (i - 1));
}

In your second case, both `i` and `i - 1` are of type `int` (then boxed to `Integer`), so the entries you're adding can also be removed...

Problem

I am unable to understand the logic behind it. Case 1: ``` HashSet shortSet = new HashSet(); for (short i = 0; i < 3; i++) { shortSet.add(i); shortSet.remove(i - 1); } System.out.println(shortSet.size() + " shortSet : " + shortSet); ``` Op :Size : 3 shortSet : [0, 1, 2] Case 2 : ``` HashSet shortSet = new HashSet(); for (int i = 0; i < 3; i++) { shortSet.add(i); shortSet.remove(i - 1); } System.out.println("Size : "+shortSet.size() + " shortSet : " + shortSet); ``` Op : Size : 1 shortSet : [2] I just want to understand the main reason behind this, why these two output are different Just By changing from short to int . what happens behind the scene.

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