Is there a way to set bounds on a variable in Java?

Question

For instance can I have a variable

int x;

and tell the compiler x can never be greater than 20 or less than -20 without having to write a method to check the value every iteration through the loop? (I should mention here this is for a vector-based game's velocity variable.

Where do you need iterations in the situation you're trying to depict in the question? — Lion, Oct 31 '12 at 16:53

score 7 · Accepted Answer · answered Oct 31 '12 at 16:58

7

Only set the variables via a setter method. Inside of this method, throw an exception if it attempts to set the value out of range. Note that this won't work on the compiler side of things but rather at runtime which is where I believe this sort of check is necessary.

answered Oct 31 '12 at 16:58

Hovercraft Full Of Eels

283,665
25
256
373

2

The usual pattern is to throw `IllegalArgumentException` from the setter when an out of range values is passed in. – Steve Kuo Oct 31 '12 at 17:49
Alright thanks. I'm accepting this answer since it was first and the others just confirmed what you said. – Ty_ Oct 31 '12 at 23:22

score 5 · Answer 2 · answered Oct 31 '12 at 16:51

5

no, you have to manually check it in your program

answered Oct 31 '12 at 16:51

ton

51
1

Aubin · Answer 3 · 2012-10-31T17:38:37.727

1

assert  -20 < x && x < 20 : "Out of range!";

Executed with -ea argument, java will check the condition, without -ea the performance are at their best.

In case of assertion will not be verified java.lang.AssertionError will be thrown

edited Oct 31 '12 at 17:38

answered Oct 31 '12 at 16:53

Aubin

14,617
9
61
84

Is there a way to set bounds on a variable in Java?

3 Answers3