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Eugene
Eugene

Reputation: 120858

enum value used in annotation where a string is expected

Suppose that I have a simple annotation:

 @MyAnnotation(value=<SomeString>)

and an enum:

 enum Days {
      MONDAY...
 }

I cant use this annotation like this:

 @MyAnnotation(value=Days.MONDAY.name())
 private class SomeClass {
       //some code
 }

This code will fail saying that "it must be a compiled time constant". I do understand why this happens and I am aware of the JSL part about compiled time constants.

My question is why and what is the reasoning behind not making an enum a compiled time constant according to the specification. It's not like you can change that enum name...

EDIT for Kumar

private static final class Test {

    public static final String complete = "start" + "finish";

}

Upvotes: 4

Views: 1779

Answers (1)

Kumar Abhinav
Kumar Abhinav

Reputation: 6675

Method dispatching cannot be computed to a compile time constant

For above example,I am giving an example as case in switch statements also require compile time constant

public class Joshua{

    public final String complete = "start" + "finish";


    public void check(String argument) {


        switch(argument)
        {
         case complete: //This compiles properly
        }

        switch(argument)
        {
         case name(): //This doesn't compile
        }
    }

    public final String name(){

        return complete;
    }

}

With final variables you know it is a compile time constant but methods are free to return anything(a final method simply cannot be overriden)

Upvotes: 2

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