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Is my laser considered a null object? (Java)


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#1 warnexus   Prime Members   -  Reputation: 1471

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Posted 28 January 2013 - 02:16 PM

laserinvalid_zpsfbcae1a5.jpg

 

I do not understand why I am getting weird data values with invalid at the end for the laser even though I created a object reference of the Laser class. The code is written in Java

 

 

 

Here's my code to the Ship and Laser class:

 
public class Ship extends Sprite implements KeyListener{
 
private Laser laser;
 
 
public Ship(Vector2D position) {
            this(position.x, position.y);
        }
        
        public Ship(double x, double y) {
            // Physics/movement stuff
            position = new Vector2D(x, y);
            velocity = new Vector2D();
            speed = 5.0;
            
            // Make the Java key listener key-repeat work as we expect
            isLeftPressed = false;
            isRightPressed = false;
            
            try {
                image = ImageIO.read(new File("src/pics/ship.PNG"));
            } 
            catch (IOException e) {
                e.printStackTrace();
            }
            
            // Add ship as a key listener
            Game.getInstance().addKeyListener(this);
        }
 
        public void keyPressed(KeyEvent e) {
            // Handle the player keys
            switch (e.getKeyCode()) {
            case (KeyEvent.VK_Z):
                laser = new Laser(getLaserSpawnPoint());
                Game.getInstance().add(laser);
                System.out.println(laser);
           
                break;
            }
        }
 
        private Vector2D getLaserSpawnPoint() {
            return new Vector2D(position.x + 22, position.y - 52);
        }
  
 
 
}
 
public class Laser extends Sprite {
    private Image image;
    private Rectangle rectangle;
    
    public Laser(Vector2D position) {
        this(position.x, position.y);
        
    }
    
    public Laser(double x, double y) {
        position = new Vector2D(x, y);
        velocity = new Vector2D(0, -5);
        
        try {
            image = ImageIO.read(new File("src/pics/laser.PNG"));
        } 
        catch (IOException e) {
            e.printStackTrace();
        }
}
 
public class Sprite extends Component implements GameComponent {
 
    public Vector2D position;
    public Vector2D velocity;
    
    @Override
    public void update(long milliseconds) {
        // TODO Auto-generated method stub
        
    }
 
    @Override
    public void draw(Graphics g) {
        // TODO Auto-generated method stub
        
    }
 
    
 
}

Edited by rip-off, 29 January 2013 - 04:16 AM.
Adding code tags


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#2 rip-off   Moderators   -  Reputation: 8517

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Posted 28 January 2013 - 03:24 PM

What is "Sprite"? It appears that the string printed is coming from this class, or perhaps yet another super class. There is some field that you are not setting, and perhaps you are not using.



#3 warnexus   Prime Members   -  Reputation: 1471

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Posted 28 January 2013 - 10:46 PM

What is "Sprite"? It appears that the string printed is coming from this class, or perhaps yet another super class. There is some field that you are not setting, and perhaps you are not using.

 

I have added the Sprite Class. happy.png The string printed is from the keyPressed method in the Ship class smile.png



#4 BitMaster   Crossbones+   -  Reputation: 4234

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Posted 29 January 2013 - 01:46 AM

You misunderstand rip-off. The string you are seeing printed is not the default behavior of Object.toString(). Accordingly, Sprite or one of its superclasses has overridden that method. It is impossible to say what any of these values mean without looking at what is actually printed.

#5 Aldacron   GDNet+   -  Reputation: 3238

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Posted 29 January 2013 - 01:49 AM

Looks to me like the "Invalid" is coming from the Rectangle instance in your Laser class. You never initialize it anywhere.

#6 Aldacron   GDNet+   -  Reputation: 3238

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Posted 29 January 2013 - 01:50 AM

You misunderstand rip-off. The string you are seeing printed is not the default behavior of Object.toString(). Accordingly, Sprite or one of its superclasses has overridden that method. It is impossible to say what any of these values mean without looking at what is actually printed.

This looks very much like the auto-generated toString output that was added to Eclipse in Galileo.

#7 warnexus   Prime Members   -  Reputation: 1471

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Posted 30 January 2013 - 10:45 PM

You misunderstand rip-off. The string you are seeing printed is not the default behavior of Object.toString(). Accordingly, Sprite or one of its superclasses has overridden that method. It is impossible to say what any of these values mean without looking at what is actually printed.

This looks very much like the auto-generated toString output that was added to Eclipse in Galileo.

thanks! it turns out that was what it actually was! I appreciated everyone's feedback as well!






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