Re: Better way to implement reverse mapping of custom enum ordinals?

From:

Lew <noone@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Sat, 19 Dec 2009 19:19:05 -0500

Message-ID:

<hgjqhr$og$1@news.albasani.net>

Tom Anderson wrote:

public enum SomeType {
    FOO(101),
    BAR(100),
    GORK(4001);

    private static class ByColumnValue {
        public static final Map<Integer, SomeType> MAP = new
HashMap<Integer, SomeType>();
    }

    private final int columnValue;

    private SomeType(int columnValue) {
        this.columnValue = columnValue;
        ByColumnValue.MAP.put(columnValue, this);
    }

    public SomeType getEnum(int columnValue) {
        return ByColumnValue.MAP.get(columnValue);
    }
}

Lew wrote:

'getEnum()' should be static.

Tom Anderson wrote:

Whoops, you're quite right, it should.

Aside: there is at least one approach to Hibernate serialization of enums
where the programmer provides for reflective use the names of the instance
method to convert an enum to an external value, and the static method for the
other direction. (IIRC they default to 'toString()' and 'valueOf()'.)

--
Lew