Java enum with multiple value types

Question

Basically what I've done is write an enum for States, and I want to not only be able to access them just as states but also access their abbreviation and whether or not they were an original colony.

public enum States {
        ...
        MASSACHUSETTS("Massachusetts",  "MA",   true),
        MICHIGAN("Michigan",            "MI",   false),
            ...; //so on and so forth for all fifty states

        private final Object[] values;

        States(Object... vals) {
            values = vals;
        }

        public String FULL() {
            return (String) values[0];
        }

        public String ABBR() {
            return (String) values[1];
        }

        public boolean ORIGINAL_COLONY(){
            return (boolean) values[2];
        }
    }

This seems to work as I'd expect it to. I can

System.out.println(States.ALABAMA);                  // Prints "ALABAMA"
System.out.println(States.ALABAMA.FULL());           // Prints "Alabama"
System.out.println(States.ALABAMA.ABBR());           // Prints "AL"
System.out.println(States.ALABAMA.ORIGINAL_COLONY());// Prints "false"

For this particular scenario involving enums, is this the best way to do this or is there a better way to setup and format this enum? Thanks to all in advance!

Not even for enums? Normally I use camel case, but I thought when referencing something static that never gets changed it should be all caps much like the enum itself would be. — Nikole
– Nikole, Commented Oct 25, 2013 at 23:04
It's also better if you actually had fields like name, abbreviation, isOriginalColony and had a constructor taking (String, String, boolean). That way, it's more readable, and also helps prevent someone adding in another state with the arguments in the wrong order. — Dennis Meng
– Dennis Meng, Commented Oct 25, 2013 at 23:05
@SonofLysander Methods themselves should always be camel case. I've only never seen all caps for enums and constants (like for example, Math.PI). — Dennis Meng
– Dennis Meng, Commented Oct 25, 2013 at 23:09
(I've also seen all caps for static final references that aren't compile-time constants, though I personally don't like that. For instance, public static final FOO = System.getProperty("foo")) — yshavit
– yshavit, Commented Oct 25, 2013 at 23:17

approxiblue · Accepted Answer · 2017-08-13 03:40:55Z

171

First, the enum methods shouldn't be in all caps. They are methods just like other methods, with the same naming convention.

Second, what you are doing is not the best possible way to set up your enum. Instead of using an array of values for the values, you should use separate variables for each value. You can then implement the constructor like you would any other class.

Here's how you should do it with all the suggestions above:

public enum States {
    ...
    MASSACHUSETTS("Massachusetts",  "MA",   true),
    MICHIGAN     ("Michigan",       "MI",   false),
    ...; // all 50 of those

    private final String full;
    private final String abbr;
    private final boolean originalColony;

    private States(String full, String abbr, boolean originalColony) {
        this.full = full;
        this.abbr = abbr;
        this.originalColony = originalColony;
    }

    public String getFullName() {
        return full;
    }

    public String getAbbreviatedName() {
        return abbr;
    }

    public boolean isOriginalColony(){
        return originalColony;
    }
}

edited Aug 13, 2017 at 3:40

approxiblue

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answered Oct 25, 2013 at 23:10

tbodt

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6 Comments

tbodt Over a year ago

@Marcin why shouldn't that be private?

Marcin Wasiluk Over a year ago

enum constructors are implicitly private

firstpostcommenter Over a year ago

How to call the method. What would States.getAbbreviatedName() will print in sysout?

firstpostcommenter Over a year ago

we can use Status.valueOf("MASSACHUSETTS").getAbbreviatedName();, Status.valueOf("MASSACHUSETTS").isOriginalColony();, etc

firstpostcommenter Over a year ago

How to have a default value in this case in-case enum does not match?

|

Kiran Maharjan · Accepted Answer · 2023-06-22 11:19:52Z

This is a filtered value from list

List<String> valueList= Stream.of(States.values())
               .filter(m->m.ORIGINAL_COLONY()==true)
                .map(m->m.ABBR())
                .collect(Collectors.toList());
    enter code here



public enum States {
    MASSACHUSETTS("Massachusetts",  "MA",   true),
    CHICAGO("Chicago",  "MA",   true),
    TROUT("trout",  "MA",   true),
    MICHIGAN("Michigan",            "MI",   false);
    private final Object[] values;

    States(Object... vals) {
        values = vals;
    }

    public String FULL() {
        return (String) values[0];
    }

    public String ABBR() {
        return (String) values[1];
    }




    public boolean ORIGINAL_COLONY(){
        return (boolean) values[2];
    }
}

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