Java – I can have different copies of static variables for each different type of inheritance class

I want the same static variable with different values, depending on the type of class

So I will

public class Entity
{
     public static Bitmap sprite;

     public void draw(Canvas canvas,int x,int y)
     {
          canvas.drawBitmap(sprite,x,y,null);
     }
}

public class Marine extends Entity
{

}

public class Genestealer extends Entity
{

}

Then in my main program:

Marine.sprite = // Load sprite for all instances of Marine
Genestealer.sprite = // Load sprite for all instances of Genestealer

I don't want to store the same sprite in every instance of the class I hope there is one for each type I want to inherit the static sprite variable and the drawing function of the drawing sprite But I don't want the genstealer elves to cover the ocean elves

Is that possible?

What should I do?

Solution

Using abstract methods:

public class Entity
{
     public abstract Bitmap getSprite();

     public void draw(Canvas canvas,int y)
     {
          canvas.drawBitmap(getSprite(),null);
     }
}

public class Marine extends Entity
{
    public Bitmap getSprite() {
        return /*the sprite*/;
    }
}

If you like, the sprite returned by getsprite can be static About the benefits of this approach:

>You can't (easily) forget to include a sprite in your subclass because the compiler will complain if you don't implement abstract methods. > It's very flexible Suppose Marines should look different once they "upgrade" Just change marine's getsprite method to take this level into account. > This is the standard OO idiom for such things, so people who look at their code don't leave their minds