Re: 'typedef enum' in Java?

[Stephen C. Upton]

Sven,

Check out pages 258-259 of Bruce Eckel's "Thinking in Java" for a 
description of another techniques for mimicking enum objects.  He has an 
int version (no type safety), and another based on strings with a private 
constructor that provides type safety.  As an aside the Enumerated stuff in 
collections is decprecated, i.e., Enumerated should no longer be used - 
instead use the Iterator methods.  Enumerated is only meant to traverse a 
list, so isn't too related to what you want to do.  For Eckel's book (2nd 
Edition, 3rd Revision in pdf and MS Word formats) see:
http://www.EckelObjects.com/TIJ2/index.html
IMHO, it's a most excellent book on java, and has alot of good stuff on 
designing also.

hope that helps
upton


At 10:47 AM 1/21/2000 -0600, you wrote:

> I'm converting an app from objC to Java, and this particular app happens 
> to use a lot of 'typedef enum' data definitions. As far as I can 
> ascertain, Java doesn't implement enumerated data types. I have therefore 
> tried to whip up an enumeration object to fill the void. (A million static 
> final constants seems messy.)
>
> I'd like comments from the Java gurus out there if this seems like a 
> reasonable solution, or if there's something else I could be doing. I 
> realize that if the object didn't contain a current value, I could 
> possibly use the Class object instead of instance objects (the data 
> variables would then just be integers). I don't see the need to iterate 
> over the possible enumerated values, so I haven't messed with the 
> Enumerated stuff in collections.
>
> Thanks!
> Sven
>
> Code follows:
> -------------
>
> // ------------------------------------------------------------------------ //
> // EnumeratedClasses.java
> // Part of NTC project "Virtual Consumer" (c) Auburn University 1999
> // ------------------------------------------------------------------------ //
>
> // The possible values for a person's ethnicity (for census purposes)
> // (Replaces an 'enumerated' data type in objC.)
>
> // Typical usages:
>
> // private CensusEthnicType myEthnicity;
> //
> // if (!myEthnicity.setValue (myEthnicity.AsianAmerican())) { .. error .. };
> // alternatively:
> // if (myEthnicity.setValue(newValue) != newValue) { .. error .. };
> //
> // if (myEthnicity.value() == myEthnicity.AsianAmerican())
> // {
> //     // do stuff
> // }
> // else if (myEthnicity.value() == myEthnicity.AfricanAmerican())
> // {
> //     // do other stuff
> // }
>
> public class CensusEthnicType {
>
>   private int value;
>   private final int MaxValue = 6;
>
>
>   // Class constructor:
>   public CensusEthnicType() {
>     value = 0;  // "not set yet"
>   }
>
>   // Number of enumerated values:
>   public int MaxValue() {
>     return MaxValue;
>   }
>
>   // Current value (out of the legal ones):
>   public int value() {
>     return value;
>   }
>
>   // Returning integer values for the enumerated alternatives:
>   // (would normally be kept 'secret')
>
>   public int EuroAmerican() {
>     return 1;
>   }
>
>   public int AfricanAmerican() {
>     return 2;
>   }
>
>   public int AsianAmerican() {
>     return 3;
>   }
>
>   public int HispanicAmerican() {
>     return 4;
>   }
>
>   public int NativeAmerican() {
>     return 5;
>   }
>
>   public int EskimoAmerican() {
>     return 6;
>   }
>
>   public boolean setValue(int v) {
>     if ((v < 1) || (v > MaxValue)) return false;
>     value = v;
>     return true;
>   }
>
>   // alternative method:
>   public int setValue (int v) {
>     if ((v < 1) || v > MaxValue)) return 0;
>     value = v;
>     return value;
>   }
>
> }
>
>
>
>                  ==================================
>   Swarm-Support is for discussion of the technical details of the day
>   to day usage of Swarm.  For list administration needs (esp.
>   [un]subscribing), please send a message to <address@hidden>
>   with "help" in the body of the message.

*** * **** * ***** ********* ** ****** ***** *** ***** ********
Stephen C. Upton  TSA-5, MS F602  Z119895                       
(505) 667-9435 Voice                    (505) 665-2017 Fax                      
address@hidden
********* ******* ********* *** ** *** ******** **** ****** ** 

                 ==================================
  Swarm-Support is for discussion of the technical details of the day
  to day usage of Swarm.  For list administration needs (esp.
  [un]subscribing), please send a message to <address@hidden>
  with "help" in the body of the message.