Generics in enums (original) (raw)

Victor Polischuk victor2 at ukr.net
Wed May 29 07:51:45 UTC 2013

Greetings,

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 extends org.apache.commons.lang.enums.Enum { public static final ColorEnum RED = new ColorEnum("Red"); public static final ColorEnum GREEN = new ColorEnum("Green"); public static final ColorEnum BLUE = new ColorEnum("Blue"); public static final ColorEnum WHITE = new ColorEnum("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 { RED("Red"), GREEN("Green"),

BLUE ("Blue"),

WHITE("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

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