How do I compare two enums?

Question

I have an enum named PawnColor which simply contains the following:

public enum PawnColor {
    black, white, none, illegal
}

If I had the following method, how could I check the color of the current instance of PawnColor?

public double ratePosition (PawnColor ratingFor)  {
    // ...
}

So if ratingFor had the color: illegal, how could I go about checking this? I've never worked with enums before, I feebly tried doing:

if(ratingFor.equals(illegal)) {
    System.out.println("Something has gone wrong.");
}

It didn't work obviously, how would I make sure that I get an error message when PawnColor ratingFor is illegal?

Why not just read a tutorial on enums? There are plenty, and you'll save yourself time in the long run... — NPE, Dec 04 '12 at 18:29
I tried one that looked as easy as it was simple but it did not work at all: http://stackoverflow.com/questions/6875677/the-best-way-to-compare-enums?rq=1 — Matt Andrzejczuk, Dec 04 '12 at 18:52
@MattAndrzejczuk what did you get? exception? no error message? — bellum, Dec 04 '12 at 19:06

bellum · Answer 1 · 2012-12-04T19:07:27.707

0

I tested this locally and error message is printed correctly.

PawnColor ratingFor = PawnColor.illegal;
if(ratingFor == PawnColor.illegal)
{
    System.out.println("Something has gone wrong.");
}

edited Dec 04 '12 at 19:07

answered Dec 04 '12 at 18:26

bellum

score 0 · Answer 2 · answered Dec 04 '12 at 18:27

0

It should be:

if (ratingFor == illegal)

answered Dec 04 '12 at 18:27

sampson-chen

Yogendra Singh · Answer 3 · 2012-12-04T18:32:54.883

0

You need to refer illegal as PawnColor.illegal.

Simply use == as :

   if(ratingFor == PawnColor.illegal)

You may also use equals as:

   if(PawnColor.illegal.equals(ratingFor))

edited Dec 04 '12 at 18:32

answered Dec 04 '12 at 18:27

Yogendra Singh

score 0 · Answer 4 · answered Dec 04 '12 at 18:31

0

For enum constants, equals and == amount to the same thing, and can be used interchangeably

answered Dec 04 '12 at 18:31

Sergii Zagriichuk

score 0 · Answer 5 · answered Dec 05 '12 at 05:53

if(ratingFor.equals(illegal)) {
    System.out.println("Something has gone wrong.");
}

Here you can not reference "illegal", ratingFor can only be compared to type PawnColor.class.

ratingFor == PawnColor.illegal

or

ratingFor.equals(PawnColor.illegal)

will give you the desired result

5 Answers5