Enums: Properties vs. Methods

From:
Robert Klemme <shortcutter@googlemail.com>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 29 Mar 2011 08:18:28 -0700 (PDT)
Message-ID:
<2f38bb8e-9a8d-4464-ad3d-b9ce0b557219@e21g2000yqe.googlegroups.com>
All,

I am just musing about the pros and cons of using boolean properties
in enum classes vs. custom methods. So far I found

pro Properties:
- less classes
- when adding enum values to an enum you cannot forget to define
properties

pro Methods:
- smaller memory footprint per instance

Considering that there are always only so many instances it seems the
properties approach wins. It seems, custom methods in enum instances
are most useful if enums do actually do something. Then different
enums can have differing implementations of the method and we have an
instance of Strategy / State pattern.

Do you have more items for the lists? Did I overlook something?

Kind regards

robert

Example
  /** We use boolean properties. */
  public enum Prop {

    A(true, true), B(true, false), C(false, true);

    private final boolean a;

    private final boolean b;

    Prop(boolean a, boolean b) {
      this.a = a;
      this.b = b;
    }

    public boolean isA() {
      return a;
    }

    public boolean isB() {
      return b;
    }
  }

  /** We use custom methods. */
  public enum Meth {
    A, B {
      @Override
      public boolean isB() {
        return false;
      }
    },
    C {
      @Override
      public boolean isA() {
        return false;
      }
    };

    public boolean isA() {
      return true;
    }

    public boolean isB() {
      return true;
    }
  }

Full toy class https://gist.github.com/892503#file_prop_vs_meth.java

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