Java 1.4 Factory Question

Question

I have a factory, and I want to restrict the possible values that may be passed into the get method.

public static class FooFactory{

 public static final String TYPE1= "type1";
 public static Foo getFoo(String type){
   switch(type){
    case "type1":
      return new Type1();
    }
   }

 }

To use this:

FooFactory.getFoo(FooFactory.TYPE1);

I'd like to restrict the parameters that may be passed in. Is an idea to make a Type abstract class, then subclass and use Type as the parameter?

Answer 1

Don't subclass it, just create a Type class with a private constructor that takes a stirng parameter, and define public Type constants.

Something like this.

public final class Type {

    public static final Type FOO = new Type( "foo" );
    public static final Type BAR = new Type( "bar" );

    private String type;

    private Type( String type ) {
      this.type = type;
    }

    public String getType() { return type; }
}