refactoring the class

[Mohit Sinha]

Hi there,

Currently I have a class which is kind of a factory implementation. The way it works is it has an Enum something like this
-----
static Enum Variables {ABC LMN PQR XYZ};
-----
This class has a method which has create method like this
----
private IVariable(String varName)
{
IVariable obj = null;
Variables val;

try {
val = Variables.valueOf(varName.toUpperCase());
switch(val)
{
case ABC:
obj = new VariableABC(); break;

case LMN:
obj = new VariableLMN(); break;

case XYZ:
obj = new VaraibleXYZ(); break;

}
}
}

----

I want to discard this switch case approach and go for alternatives I guess (reflection will be most appropriate). Do post your comments on what approach should i opt for in the above scenario.

Regards,

[Adam Teg]

You can pass in the Class.class and return the needed type.

[Garrett Rowe]

I'd stay away from reflection unless you really need it, and in this case I'm almost certain you dont. I guess this is a made-up example and not real code because there are a few things there that just don't make sense. Regardless, one solution would be to let the enum instance itself create the variable:

enum Variables {
   ABC {
   @Override
      public Var makeVar() {
         return new VariableABC();
      }
   },
 
   LMN {
   @Override
      public Var makeVar() {
         return new VariableLMN();
      }
   },
   //...
 
   public abstract Var makeVar()
}
 
private IVariable(String varName)
{
   Variables val = Variables.valueOf(varName.toUpperCase());
   
   if (val == null) 
      throw new IllegalArgumentExcepiton("Unknown argument: " + varName);
 
   Var v = val.makeVar();
}

[ September 15, 2008: Message edited by: Garrett Rowe ]

[Mohit Sinha]

Hi Garrett

Thanks for the info and apologize for the unclear question. Why I mentioned about a dynamic approach was there could be 500 such variables and I don't want to repeat the same operation over and over again.

Is there such an option available.

Thanks

[Paul Clapham]

Then why not just use the static "valueOf" method of the Enum class which takes a String and returns the enum value which corresponds to that string? No reflection required. Not even a switch statement required.

[Rob Spoor]

And you need a VariableXYZ for each enumeration value anyway, so why not put that code in the enumeration itself? That way, if you add a new item to the enumeration, all your other code immediately works.