JAVA Greenfoot Game Over / Win check on yCoordinate

Question

I'm having this issue with my 2 checks for a frogger-style game. So the Gameover check is a simple collision check on the frog object.

The next check does a getY coord check for checking if the frog object has hit the roof of the world ergo has beaten the game.

Now when the GameOver check is fulfilled there is no more object to do a getY check on. So it gives an error. How can I bypass this ?

full code of the Frogger class:

public class Frogger extends Actor
{
public void act() 
{
    checkKeys();
    hitEnemy();
    atTop();

}    

private void checkKeys()
{
    if (Greenfoot.isKeyDown("up")) {
        setLocation(getX(), getY()-3);
    }
    if (Greenfoot.isKeyDown("down")) {
        setLocation(getX(), getY()+3);
    }
    if (Greenfoot.isKeyDown("left")) {
        setLocation(getX()-3, getY());
    }
    if (Greenfoot.isKeyDown("right")) {
        setLocation(getX()+3, getY());
    }

}

public void hitEnemy()
{
    Actor Enemy = getOneIntersectingObject(Enemy.class);
    if(Enemy != null)
    {   
        World myWorld = getWorld();
        Gameover gameover = new Gameover();
        myWorld.addObject(gameover, 300, 200);
        myWorld.removeObject(this);   
    }
}

private void atTop()
{
    if (getY() < 30)
    {   
        World myWorld = getWorld();
        Youwin youwin = new Youwin();
        myWorld.addObject(youwin, 300, 200);
        myWorld.removeObject(this);   
    }
  }

}

Answer 1

Different approaches. When the game is over, you could just not do a getY() check anymore. Do not continue running the game, but rather to back to a main menu or something. the getY() method is irrelevant here. You could halt the program completely.

But your code looks weird. GameOver is an object? Rather than a simple method in your game. It does look like your code has a weird structure for a game. Anyway, when the game is over the 'gamelogic' loop should no longer be running, bur rather go to a menu.

Or you could keep the game running and do a null check. But reading your code, it seems like the whole structure is not that good. Is the aTop part of your Frog class? If so, it should exist for it to be called on. If you remove the Frog class from the world, you could do something like (but I do not see where the aTop method gets called)

 if(myWorld.getFrog()!=null){
   // Get method
}

Could you maybe share a bit more of your code? I think this should give you an idea though, there should be no more calls to the object when the object is removed, because the game ended and the normal game loop should no longer be running. And otherwise, nullchecks.