Alex Rivera | Logout

Pick a random value from an enum?

Asked 2009-12-29T00:54:29.203
224

If I have an enum like this:

public enum Letter {
    A,
    B,
    C,
    //...
}

What is the best way to pick one randomly? It doesn't need to be production quality bulletproof, but a fairly even distribution would be nice.

I could do something like this

private Letter randomLetter() {
    int pick = new Random().nextInt(Letter.values().length);
    return Letter.values()[pick];
}

But is there a better way? I feel like this is something that's been solved before.

java random enums
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3

If you do this for testing you could use Quickcheck (this is a Java port I've been working on). 

import static net.java.quickcheck.generator.PrimitiveGeneratorSamples.*;

TimeUnit anyEnumValue = anyEnumValue(TimeUnit.class); //one value

It supports all primitive types, type composition, collections, different distribution functions, bounds etc. It has support for runners executing multiple values:

import static net.java.quickcheck.generator.PrimitiveGeneratorsIterables.*;

for(TimeUnit timeUnit : someEnumValues(TimeUnit.class)){
    //..test multiple values
}

The advantage of Quickcheck is that you can define tests based on a specification where plain TDD works with scenarios.

answered 2009-12-29T09:28:41.083

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