Parameterizing the return type of a method using an enum -- possible?

In java, I know it's possible to e.g.:

static <T> void fromArrayToCollection(T[] a, Collection<T> c) {
    for (T o : a) {
        c.add(o); // Correct
    }
}

In my scenario, I have an enumeration of different settings I can retrieve a value for, where each setting has a different value type. I'd like to specify these value types in the enumeration, and get compile-time checking similar to the above.

Here is a version with runtime checking -- is compile-time checking possible?

public class Foo {
  public static enum ClientSetting {
    SOME_STRING_SETTING(String.class),
    SOME_INTEGER_SETTING(Integer.clas开发者_Go百科s);

    private Class valueClass;

    ClientSetting(Class valueClass) {
      this.valueClass = valueClass;
    }
  }

  public static <T> T get(ClientSetting bar) {
    if (bar.valueClass.equals(String.class))
      return (T) "My string value.";
    else if (bar.valueClass.equals(Integer.class))
      return (T) new Integer(2);
    else
      return null; // unreachable if every possibility is  checked
  }

  public static void main(String[] args) {
    String stringValue = get(ClientSetting.SOME_STRING_SETTING);
    Integer integerValue = get(ClientSetting.SOME_INTEGER_SETTING);
  }
}

Thanks!

dacc, would something like this work for you?

public static class ClientSetting<T> {
   private T setting;

   ClientSetting(T setting) {
      this.setting = setting;
   }

   public T get() {
      return setting;
   }
}

// Old school, I know.
public static final ClientSetting<String> SOME_STRING_SETTING = 
   new ClientSetting<String>("My string value.");
public static final ClientSetting<Integer> SOME_INTEGER_SETTING = 
   new ClientSetting<Integer>(2);

public static <T> T get(ClientSetting<T> clientSetting) {
   // delegation, this method is not really needed
   // you can go for SOME_STRING_SETTING.get()
   return clientSetting.get();
}

public static void main(String[] args) {
   String stringValue = get(SOME_STRING_SETTING);
   Integer integerValue = get(SOME_INTEGER_SETTING);
   // Won't compile
   // String wrong = get(SOME_INTEGER_SETTING);
}

I'm not sure if this would help, but what if you put a generic on ClientSetting? You could pass around ClientSetting<String> or ClientSetting<Integer>. Assuming you were coding to a specific one of these, some compile-time checking would occur.