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

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.