Cohesion / Coupling example 3

00 Original.java

class Game {
    int ballX = 0;
    int ballY = 0;
    int ballYSpeed = 3;
    int paddleX = 30;
    int paddleY = 500;
    
    public void update() {
        ballX = ballX + 5;
        ballY = ballY + ballYSpeed;
        if (ballX + 30 >= paddleX
            && ballX <= paddleX + 150
            && ballY + 30 >= paddleY
            && ballY <= paddleY + 12
            ) {
            ballYSpeed = -3;
        }
    }
}

01a Worse.java

class Ball {
    int x = 0;
    int y = 0;
    int ySpeed = 3;

    public void move(Paddle paddle) {
        x = x + 5;
        y = y + ySpeed;
        if (x + 30 >= paddle.x
            && x <= paddle.x + 150
            && y + 30 >= paddle.y
            && y <= paddle.y + 12
            ) {
            ySpeed = -3;
        }
    }
}

class Paddle {
    int x = 30;
    int y = 500;
}

class Game {
    Ball ball = new Ball();
    Paddle paddle = new Paddle();

    public void update() {
        ball.move(paddle);
    }
}

01b Worse.java

class Ball {
    int x = 0;
    int y = 0;
    int ySpeed = 3;
    Paddle paddle = new Paddle();

    public void move() {
        x = x + 5;
        y = y + ySpeed;
        if (x + 30 >= paddle.x
            && x <= paddle.x + 150
            && y + 30 >= paddle.y
            && y <= paddle.y + 12
            ) {
            ySpeed = -3;
        }
    }
}

class Paddle {
    int x = 30;
    int y = 500;
}

class Game {
    Ball ball = new Ball();

    public void update() {
        ball.move();
    }
}

02 Better.java

class Ball {
    int x = 0;
    int y = 0;
    int ySpeed = 3;

    public void move(Paddle paddle) {
        x = x + 5;
        y = y + ySpeed;
    }
    
    public void bounceUp() {
        ySpeed = -3;
    }
}

class Paddle {
    int x = 30;
    int y = 500;
}

class Game {
    Ball ball = new Ball();
    Paddle paddle = new Paddle();

    public void update() {
        ball.move(paddle);
        if (ball.x + 30 >= paddle.x
            && ball.x <= paddle.x + 150
            && ball.y + 30 >= paddle.y
            && ball.y <= paddle.y + 12
            ) {
            ball.bounceUp();
        }
    }
}

03 Ideal.java

class Ball {
    int x = 0;
    int y = 0;
    int ySpeed = 3;

    public void move(Paddle paddle) {
        x = x + 5;
        y = y + ySpeed;
    }
    
    public void bounceUp() {
        ySpeed = -3;
    }
    
    public Rectangle getBounds() {
        return new Rectangle(x, y, 30, 30);
    }
}

class Paddle {
    int x = 30;
    int y = 500;
    
    public Rectangle getBounds() {
        return new Rectangle(x, y, 150, 12);
    }
}

class Game {
    Ball ball = new Ball();
    Paddle paddle = new Paddle();

    public void update() {
        ball.move(paddle);
        
        Rectangle ballBounds = ball.getBounds();
        Rectangle paddleBounds = paddle.getBounds();
        
        if (ballBounds.intersects(paddleBounds)) {
            ball.bounceUp();
        }
    }
}