Fw: Generics in enums

[Victor Polischuk]

Greetings,

I beg pardon for the previous HTML mail.

Some time ago I wanted to migrate our "commons-lang" enums to "java 5" enumerations, but I encountered an issue that it cannot be done without discarding generics since java enums do not support them. Let me show an example:

//------
public final class ColorEnum<T extends Pixel> extends org.apache.commons.lang.enums.Enum {
    public static final ColorEnum<PurePixel> RED = new ColorEnum<PurePixel>("Red");
    public static final ColorEnum<PurePixel> GREEN = new ColorEnum<PurePixel>("Green");
    public static final ColorEnum<PurePixel> BLUE = new ColorEnum<PurePixel>("Blue");
    public static final ColorEnum<MixedPixel> WHITE = new ColorEnum<MixedPixel>("White") {
        @Override
        public MixedPixel make() {...} 
    };
    
    private ColorEnum(String color) {super(color);}
    
    public boolean filter(T pixel) {...}
    
    public T make() {...}
}
//------

And I wonder if there is a specific reason why I cannot convert it into something like: 

//------
public enum Color<T extends Pixel> {
    RED<PurePixel>("Red"),
    GREEN<PurePixel>("Green"),
    BLUE<PurePixel>("Blue"),
    WHITE<MixedPixel>("White") {
        @Override
        public MixedPixel make() {...} 
    };

    private Color(String color) {...}

    public boolean filter(T pixel) {...}

    public T make() {...}
}
//------

Thank you in advance.

Sincerely yours,
Victor Polischuk