Thread: Collision Testing Code isnt working.

For some reason the ball is still going off the top of the frame. Im not sure why.

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import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
 
import javax.swing.JFrame;
 
 
public class Frame extends JFrame
{
	int ovalSpeed = 5;
	int xCoord = 50; 
	int yCoord = 50;
	private final int ovalWidth = 25;
	private final int ovalHeight = 25;
	private final int WIDTH = 800;
	private final int HEIGHT = WIDTH / 5 * 4;
	private Dimension borderlessSize;
	private Image dbImage;
	private Graphics dbG;
	private Dimension d = new Dimension(WIDTH, HEIGHT);
 
	//Constructor for the class, and makes the frame.
	Frame()
	{
		addKeyListener(new AL());
		setTitle("Frame");
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setSize(d);
		setResizable(false);
		setVisible(true);
		setBackground(Color.WHITE);
 
		borderlessSize = this.getContentPane().getSize();
 
		System.out.println(borderlessSize.getWidth() + " " + borderlessSize.getHeight());
	}
	//Draws graphics on the screen.
	public void paint(Graphics g)
	{
		dbImage = createImage(getWidth(), getHeight());
		dbG = dbImage.getGraphics();
		paintComponent(dbG);
		g.drawImage(dbImage, 0, 0, this);
	}
 
	public void paintComponent(Graphics g)
	{
		g.fillOval(xCoord, yCoord, ovalWidth, ovalHeight);
 
		repaint();
	}
	public class AL extends KeyAdapter
	{
		public void keyPressed(KeyEvent e)
		{
			int keyCode = e.getKeyCode();
 
			//If left arrow is pressed.
			if(keyCode == e.VK_LEFT)
			{
				//Tests they're past the left hand portion of the screen, of so, then set its xCoord to 0.
				if(xCoord <= 0)
				{
					xCoord = 0;
				}
				//Moves the ball ovalSpeed pixels to the left.
				else
				{
					xCoord += -ovalSpeed;
				}
			}
			//If right arrow is pressed.
			if(keyCode == e.VK_RIGHT)
			{
				//Tests they're past the right hand portion of the screen, of so, then set its xCoord to the width of the frame - the width of the oval.
				if(xCoord >= borderlessSize.getWidth() - ovalWidth)
				{
					xCoord = (int) (borderlessSize.getWidth() - ovalWidth);
				}
				//Moves the ball ovalSpeed pixels to the right.
				else
				{
					xCoord += ovalSpeed;
				}
			}
			//If up arrow is pressed.
			if(keyCode == e.VK_UP)
			{
				//Tests they're higher then the upper hand portion of the screen, of so, then set its yCoord to 0.
				if(yCoord <= 0)
				{
					System.out.println(yCoord);
					System.out.println("top collision");
					yCoord = 0;
				}
				//Moves the ball ovalSpeed pixels up.
				else
				{
					System.out.println(yCoord);
					yCoord += -ovalSpeed;
				}
			}
			//If down arrow is pressed.
			if(keyCode == e.VK_DOWN)
			{
				//Tests they're lower the lower hand portion of the screen, of so, then set its yCoord to the height of the frame - the height of the oval.
				if(yCoord >= borderlessSize.getHeight() - ovalHeight)
				{
					yCoord = (int) (borderlessSize.getHeight() - ovalHeight);
				}
				//Moves the ball ovalSpeed pixels down.
				else
				{
					yCoord += ovalSpeed;
				}
			}
		}
	}
}

There are so many basic mistakes in painting/graphics here. For example, calling repaint() from inside paintComponent() is just plain wrong, if you were actually overriding paintComponent(), which you're not. You should learn why it's wrong, why you should be overriding paintComponent() and how when you read the Custom Painting Lesson, (the whole thing). After you've applied what you learn in that lesson to your source code, come back with your changes and when you're ready for help.

Also, don't name your classes the same as existing core Java classes. It's bad form and will eventually (if not immediately) result in headaches.