What is the fully qualified class name of an enum defined locally within a method?

Question

As of Java 16, we can now define an enum locally, within a method. This feature came as part of the work for the new records feature. (Interfaces too can be local, by the way.)

What is the fully-qualified name of such a locally-defined enum class?

The following code works if I were define the enum in a separate .java file. How should I change this fully-qualified class name for a local enum?

package work.basil.example.enums;

public class EnumMagic
{
    public static void main ( String[] args )
    {
        EnumMagic app = new EnumMagic ( );
        app.demo ( );
    }

    private void demo ( )
    {
        enum Shape { CIRCLE, SQUARE }
        try
        {
            Class < ? > clazz = Class.forName ( "work.basil.example.enums.Shape" );
            System.out.println ( "clazz = " + clazz );
        }
        catch ( ClassNotFoundException e ) { throw new RuntimeException ( e ); }
    }
}

As currently written, I understandably get an java.lang.ClassNotFoundException: work.basil.example.enums.Shape.

Neither of these work:

• "work.basil.example.enums.EnumMagic.Shape"
• "work.basil.example.enums.EnumMagic.$Shape"

Answer 1

Local classes, enums and interfaces don't have a qualified name. Just a simple name. In your case: Shape

From: https://docs.oracle.com/javase/specs/jls/se15/preview/specs/local-statics-jls.html#jls-14.3

Answer 2

I gleaned the following info from the comments on the Answer by Mar-Z.

Class#getName

You can discover the name of the class in question by interrogating through Java code. Call Class#getName, like this:

Shape.class.getName()

Example:

System.out.println ( Shape.class.getName() );  

work.basil.example.enums.EnumMagic$1Shape

So we can plug that into the Question’s code.

enum Shape { CIRCLE, SQUARE }
try
{
    Class < ? > clazz = Class.forName ( "work.basil.example.enums.EnumMagic$1Shape" );
    System.out.println ( "clazz = " + clazz );
}
catch ( ClassNotFoundException e ) { throw new RuntimeException ( e ); }

clazz = class work.basil.example.enums.EnumMagic$1Shape

Caveat: Unfortunately, this hard-coded class name string is fragile. The name could change in later builds of your code. See discussion in Comments below.