Extending enum

Question

public enum myEnum {    
VAL1(10), VAL2(20), VAL3("hai") {
     public Object getValue() {
      return this.strVal;
     }
     public String showMsg() {
      return "This is your msg!";
     }
    };
    String strVal;
    Integer intVal;
    public Object getValue() {
     return this.intVal;
    }
    private myEnum(int i) {
     this.intVal = new Integer(i);
    }
    private myEnum(String str) {
     this.strVal = str;
    }
}

In the above enum what exactly happens when I add a constant specific class body for VAL3?

The type of VAL3 is definetly a subtype of myEnum as it has overloaded and additional methods. (the class type comes as 'myEnum$1' )

But how can the compiler creates a subtype enum extending myEnum as all the enums are already extending java.lang.enum ?

Answer 1

Your class myEnum inherits from java.lang.Enum. VAL3 is an anonymous inner class that inherits from myEnum called myEnum$1. Think of the enum keyword as syntatic sugar. It sets up classes with normal inheritance trees for you, but will not allow you to extend java.lang.Enum or myEnum directly.

Answer 2

From decompiler

package com.sun.tools.xjc.outline;


public final class Aspect extends Enum
{
    public static final Aspect EXPOSED;
    public static final Aspect IMPLEMENTATION;
    private static final Aspect $VALUES[];

    static 
    {
        EXPOSED = new Aspect("EXPOSED", 0);
        IMPLEMENTATION = new Aspect("IMPLEMENTATION", 1);
        $VALUES = (new Aspect[] {
            EXPOSED, IMPLEMENTATION
        });
    }

    public static final Aspect[] values()
    {
        return (Aspect[])$VALUES.clone();
    }

    public static Aspect valueOf(String name)
    {
        Aspect arr$[] = $VALUES;
        int len$ = arr$.length;
        for(int i$ = 0; i$ < len$; i$++)
        {
            Aspect aspect = arr$[i$];
            if(aspect.name().equals(name))
                return aspect;
        }

        throw new IllegalArgumentException(name);
    }

    private Aspect(String s, int i)
    {
        super(s, i);
    }


}