Best way to implement the Factory Pattern in Java

Question

I am trying to write a Factory Pattern to create either a MainMode or a TestMode in my program. The code I was previously using to create these objects was:

Answer 1

The whole point of a Factory is that it should have the needed state to create your Game appropriately.

So I would build a factory like this:

public class GameFactory {
   private boolean testMode;

   public GameFactory(boolean testMode) {
     this.testMode = testMode;
   }

   public Game getGame(int numberRanges, int numberOfGuesses) {
     return (testMode) ? new MainMode(numberRanges, numberOfGuesses) : 
       new TestMode(numberRanges, numberOfGuesses, getRandom());
   }

   private int getRandom() {
     . . . // GUI code here
   }
}

Now you can initialize this factory somwhere in your app, and pass it in to whatever code needs to create a Game. This code now doesn't need to worry about what mode it is, and passing extra random params - it uses a well known interface to create Games. All the needed state is internalized by the GameFactory object.

Answer 2

interface ModeFactory {
    Mode createMode(int numberRanges, int numberOfGuesses);
}

class MainModeFactory implements ModeFactory {
    Mode createMode(int numberRanges, int numberOfGuesses) {
        return new MainMode(numberRanges, numberOfGuesses);
    }
}

class TestModeFactory implements ModeFactory {
    Mode createMode(int numberRanges, int numberOfGuesses) {
        return new TestMode(numberRanges, numberOfGuesses, randNo());
    }
}

...

play = modeFactory.createMode(numberRanges, numberOfGuesses);

So at startup you create the appropriate mode factory, passing it in to wherever the play needs to be created.