modifying enums

[Hengki Widjaja]

I have an enum like this:

Color {Blue,Green,Yellow}

and I have a file containing specification like this:

Blue=This is blue
Green=This is green
Yellow=This is yellow

What should I do so that when I do System.out.println(Color.Blue); it will produce "This is blue". And I certainly don't want to make toString() functions for every value because I'm going to have lots of enums. It's assured that every enum value will have a counterpart in the file with exact same name (case-sensitive). thanks

[Harsha Smith]

Probably this is how you should do

enum Color{
	
	Blue, Green, Yellow;
	
	@Override
	
	public String toString(){
		
		return "This is "+this.name();
	}
}

[Rob Spoor]

Use a java.util.Properties object. You can use it to read your file, and also to map the names. If you use it in a utility class you can then simply use that utility class wherever you need to get the label for an enum:

public final class EnumLabels
{
    private static final Properties PROPERTIES = new Properties();

    static
    {
        // load the contents of the file here
    }

    private EnumLabels()
    {
        // private constructor to prevent initialization
    }

    public static String getLabel(Enum<?> enum)
    {
        return PROPERTIES.getProperty(enum.name(), enum.name()); // default to enum.name() if not found
    }
}

You then use EnumLabels.getLabel(e) instead of e.toString().

[Rob Spoor]

Harsha Smith wrote:Probably this is how you should do

enum Color{
	
	Blue, Green, Yellow;
	
	@Override
	
	public String toString(){
		
		return "This is "+this.name();
	}
}

Except a) the labels are not fixed but are stored in a file, so you can't hard code them, and b) Hengki stressed that he does not want to override toString().

[Matthew Brown]

Here's one approach. The first thing you can do is give your enums a member variable containing the description. Here's an example that hard-codes them instead of loading from a file:

enum Colour { // sorry, I'm British :) 
    BLUE("This is blue"), GREEN("This is green"), YELLOW("This is yellow");

    private String name;

    private Colour(String name) { this.name = name; }

    public String toString() { return name; }
}

Then you could probably add a static initializer block (or maybe something in the constructor, or a bit of both) to load the names from a file. You'd want to factor the working out into another class to minimise the additional plumbing you need to add to each enum.

[Hengki Widjaja]

Thanks guys. It worked. Have a nice day to you all!!!