Java - Force implementation of an implemented method

Question

I have three classes which I have a problem with. They are named: GameScene, StageScene, StageOne. My problem is that I want to implement initialize in StageScene, but still force StageOne to implement it, so that whenever someone uses a StageOne object (stageOne.initialize()), initialize would be run for both StageScene and StageOne. Anyone know how this could be done?

public abstract class GameScene 
{
    public abstract void initialize();
}

public abstract class StageScene extends GameScene
{
    public abstract void initialize()
    {
        //Some code
    }
}
public class StageOne extends StageScene
{
    public void initialize()
    {
        //Some code
    }
}

Thanks, this question helped me think about a design problem I'm handling — Dan Rosenstark, May 15 '14 at 00:26

score 7 · Accepted Answer · answered Mar 12 '12 at 22:32

7

you can do it with a wrapper:

public abstract class StageScene extends GameScene
{
    final public void initialize()
    {
        //your initialization
        subInitialize();
    }

    protected abstract void subInitialize();
}

And in the child class:

public class StageOne extends StageScene
{
    public void subInitialize()
    {
        //Some code
    }
}

answered Mar 12 '12 at 22:32

MByD

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@assylias - sure. made minimal changes to the original code, but you are right. – MByD Mar 12 '12 at 22:35

score 1 · Answer 2 · answered Mar 12 '12 at 22:32

You could break it into two separate methods

public abstract class GameScene 
{
    public abstract void initializeScene();
    public abstract void initializeStage();
}

public abstract class StageScene extends GameScene
{
    public void initializeScene()
    {
        //Some code
    }
}
public class StageOne extends StageScene
{
    public void initializeStage()
    {
        //Some code
    }
}

Java - Force implementation of an implemented method

2 Answers2

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