Re: Enums: Properties vs. Methods

Lew <>
Sat, 02 Apr 2011 10:36:44 -0400
On 04/02/2011 05:23 AM, Wanja Gayk wrote:

In article<2f38bb8e-9a8d-4464-ad3d-b9ce0b557219>, says...


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

pro Methods:
- smaller memory footprint per instance

Quite frankly: Use what's easier to read and maintain.
Memory and runtime should be your smallest concern, assuming you use
some common sense when chosing your algorithm, only if there's clearly a
problem for the user and the system you should optimize to something
probably less readable. To find bottlenecks, don't guess, but use a
profiling tool. "jvisualvm" (which you can find in your jdk/bin folder)
is not bad for a start.

   /** 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;

Like proposed elsewhere you could also write (untested):

    public enum Prop {
        public boolean isA(){return true;}
        public boolean isB(){return true;}

        public boolean isA(){return true;}
        public boolean isB(){return false;}
        public boolean isA(){return false;}
        public boolean isB(){return true;}

      public abstract boolean isA();
      public abstract boolean isB();

Consider that the use of boolean parameters is often quite bad to read
and maintain. Just have a look at your boolean initializer:

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

You can't tell from looking at the code, whether the first argument
represents the return value for "isA" or "isB". From this point of view,
with a proper formatting, I'd prefer the abstract method approach.

I get your point about the parameter approach, but in an enum where everything
is together and nothing is public that is much less of a confusion. For that
I'd go with the first form for clarity and simplicity.

Honi soit qui mal y pense.

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