Any way to make this simple tennis game more OO?

Huw Fulcher · 2014-04-26T18:42:50

Hey all, I'm a 1st year CS student and I'm making my first pet project in Java, the idea is taken from this tutorial (http://www.edu4java.com/en/game/game6.html) but I didn't want to continue following the tutorial because I wanted to get my hands dirty and dive in trying to work it out myself. Currently the code has three classes: - Game which is the main class that sets up the KeyListener, game loop and painting of the screen - Ball which creates the ball sprite and works out the position on screen when the move() and paint() methods are called - Racquet which is the same as Ball but a different shape obviously. My question is, can I separate the Game class and make a Board class that deals with creating the window and then leave the Game class to run the loop only? I've tried doing so but I've discovered circular dependencies between Board, Ball and Racquet if I do that. I can do it using setters in the Board class to reference the Ball and Racquet class but I can't get the KeyListener working in that case and I think there must be a slicker way of doing it The code is below: Game: import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.RenderingHints; import java.awt.event.KeyEvent; import java.awt.event.KeyListener; import javax.swing.JFrame; import javax.swing.JPanel; /** * Created by HuwF on 24/04/2014. */ public class Game extends JPanel { //Create sprite objects Ball ball = new Ball(this); Racquet racquet = new Racquet(this); public Game() { //Implement listener to move keyboard addKeyListener(new KeyListener() { @Override public void keyTyped(KeyEvent e) { } @Override public void keyPressed(KeyEvent e) { //Call racquet to move it racquet.keyPressed(e); } @Override public void keyReleased(KeyEvent e) { //Stops racquet movement racquet.keyReleased(e); } }); setFocusable(true); } //Gets objects to update position and movement values public void move() { ball.move(); racquet.move(); } //Paints screen based on sprite's values @Override public void paint(Graphics g) { super.paint(g); Graphics2D g2d = (Graphics2D)g; ball.paint(g2d); racquet.paint(g2d); } public static void main(String[] args) throws InterruptedException { //Create and display frame JFrame frame = new JFrame("Mini Tennis"); Game game = new Game(); frame.add(game); frame.setSize(300, 400); frame.setVisible(true); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Main game loop - I want everything apart from this in the Board class while (true) { game.move(); game.repaint(); Thread.sleep(10); } } } Ball: import java.awt.Graphics2D; /** * Created by HuwF on 24/04/2014. */ public class Ball { //Ball coordinates int x = 0; int y = 0; //1 = Right, 0 = Still, -1 = Left int xDirection = 1; //1 = Up, 0 = Still, -1 = Down int yDirection = 1; private Game game; public Ball(Game game) { this.game= game; } void move() { //If ball is by left edge of screen, direction reverses if (x + xDirection < 0) { xDirection = 1; } //If ball is by right edge of screen, direction reverses if (x + xDirection > this.game.getWidth() - 30) { xDirection = -1; } //If ball is by the bottom of screen, direction reverses if (y + yDirection < 0) { yDirection = 1; } //If ball is by the top of screen, direction reverses if (y + yDirection > this.game.getHeight() - 30) { yDirection = -1; } //If ball is no where near screen border continue along path x = x + xDirection; y = y + yDirection; } public void paint(Graphics2D g) { //Draw sprite on screen g.fillOval(x, y, 30, 30); } } Racquet: import java.awt.*; import java.awt.event.KeyEvent; /** * Created by HuwF on 24/04/2014. */ public class Racquet { //Position, racquet can only move left or right int x = 0; //Direction, -1 = Left, 0 = Still, 1 = Right int xDirection = 0; private Game game; public Racquet(Game game) { this.game = game; } public void move() { //If not near the left or right edge of the screen then move in current direction if ((x + xDirection > 0) && (x + xDirection < this.game.getWidth() - 60)) { x = x + xDirection; } } public void paint(Graphics2D g) { //Draw sprite on screen g.fillRect(x, 330, 60, 10); } //When a key is released the racquet stops moving public void keyReleased(KeyEvent e) { xDirection = 0; } public void keyPressed(KeyEvent e) { //If left arrow is pressed direction is changed to left if (e.getKeyCode() == KeyEvent.VK_LEFT) { xDirection = -1; } //If right arrow is pressed direction is changed to right if (e.getKeyCode() == KeyEvent.VK_RIGHT) { xDirection = 1; } } } Thanks in advance!

For Beginners

Started by HuwFulcher April 24, 2014 02:21 PM

11 comments, last by tufflax 10 years, 9 months ago

Glass_Knife

8,637

April 25, 2014 03:36 PM

IMO, that's the wrong way to think about software architecture. It doesn't matter "how OO" a codebase is. What matters is how easy it is to maintain. Object orientation is just one tool of several that you can use to get the job done. The danger of focusing so much on OO is that you wind up with a rigid, inflexible monster that makes it impossible to make changes without negative consequences (like code breakage, or increased complexity of implementation).

Yep. I saw a video of Jonathan blow talking about how he coded stuff in Braid. It was very interesting. He would just put a comment in a function instead of creating a new funtion, wrap that code in braces, and then code away, knowing that the code wasn't going to break any other code. From an 'OO' point of view this is just rubbish, but when you're one of a few people trying to fix a bug in a game so you can ship it, you'd rather rewrite the same code snippet 10 times and test each fix once than change a function used in thousands of spots and have to test thousands of things when you make a change.


void someFunc() {

   // fix a bug here
   {
      // here is some code, wrapped in braces,
      // so the scope can't possible cause problems
      // anywhere else.  I can change this code all 
      // I want and not break anything else
   }
}

This may be going to far, but I really had to stop and think about it. I'm still thinking about it...

I think, therefore I am. I think? - "George Carlin"
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HuwFulcher

Author

124

April 25, 2014 04:07 PM

IMO, that's the wrong way to think about software architecture. It doesn't matter "how OO" a codebase is. What matters is how easy it is to maintain. Object orientation is just one tool of several that you can use to get the job done. The danger of focusing so much on OO is that you wind up with a rigid, inflexible monster that makes it impossible to make changes without negative consequences (like code breakage, or increased complexity of implementation).

Yep. I saw a video of Jonathan blow talking about how he coded stuff in Braid. It was very interesting. He would just put a comment in a function instead of creating a new funtion, wrap that code in braces, and then code away, knowing that the code wasn't going to break any other code. From an 'OO' point of view this is just rubbish, but when you're one of a few people trying to fix a bug in a game so you can ship it, you'd rather rewrite the same code snippet 10 times and test each fix once than change a function used in thousands of spots and have to test thousands of things when you make a change.
void someFunc() {

   // fix a bug here
   {
      // here is some code, wrapped in braces,
      // so the scope can't possible cause problems
      // anywhere else.  I can change this code all 
      // I want and not break anything else
   }
}
This may be going to far, but I really had to stop and think about it. I'm still thinking about it...

Interesting idea! I'm going to focus on just coding out the program first and then see what can be made modular without causing too much grief in the long run

tufflax

504

April 26, 2014 06:42 PM

This is all you need: http://www.infoq.com/presentations/Simple-Made-Easy

Any way to make this simple tennis game more OO?

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Any way to make this simple tennis game more OO?

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