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Thread: Exception in Main NullPointerException?

  1. #1
    Junior Member lil_misfitss's Avatar
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    Unhappy Exception in Main NullPointerException?

    Hello!
    I'm trying to make a program where the ball moves to the right of the screen but my program compiles correctly. It's when I run it is when this pops up:
    Exception in thread "main" java.lang.NullPoinerException
    at java.awt.Container.addImpl(Unknown Source)
    at java.awt.Container.add(Unknown Source)
    at javax.swing.JFrame.addImpl(Unknown Source)
    at java.awt.Container.add(Unknown Source)
    at FirstGame.<init><FirstGame.java:18>
    at FirstGame.main<FirstGame.java:27>

    import javax.swing.*;
    import java.awt.*;
    import java.awt.event.*;
    import java.awt.geom.*;
    import java.util.*;
    import java.util.concurrent.*;
    //Start
    class FirstGame extends JFrame
    {
    	private PaintSurface canvas;
     
    	public FirstGame() 
    	{
    		JFrame frame = new JFrame();
    		frame.setSize(800, 600);
    		frame.setResizable(false);
    		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    		frame.add(canvas,BorderLayout.CENTER);
     
    		ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(3);
    		executor.scheduleAtFixedRate(new paintSpriteThread(frame), 0L, 20L, TimeUnit.MILLISECONDS);
     
    	}
     
    	public static void main(String[] args)
    	{
    		new FirstGame();
    	}
    }
    class paintSpriteThread implements Runnable
    {
     
    	JFrame c;
     
    	public paintSpriteThread(JFrame c)
    	{
    		this.c = c;
    	}
     
    	public void run()
    	{
    		c.repaint();
    	}
    }
     
    class PaintSurface extends JComponent
    {
    	int x = 400;
     
    	int y = 300;
     
    	int d = 20;
     
    	public void paint(Graphics g)
    	{
    		Graphics2D g2 = (Graphics2D)g;
    		g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
    		Shape ball = new Ellipse2D.Float(x,y,d,d);
     
    		x+=1;
     
    		g2.setColor(Color.RED);
    		g2.fill(ball);
    	}
    }

    Welp, with every error I will learn something new!
    Thank you to all who reply with helpfullness!
    lil_misfit


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Exception in Main NullPointerException?

    Exception in thread "main" java.lang.NullPoinerException
    at java.awt.Container.addImpl(Unknown Source)
    at java.awt.Container.add(Unknown Source)
    at javax.swing.JFrame.addImpl(Unknown Source)
    at java.awt.Container.add(Unknown Source)
    at FirstGame.<init><FirstGame.java:18>
    There is a null value in the add() statement called on line 18.
    If you don't understand my answer, don't ignore it, ask a question.

  3. The Following User Says Thank You to Norm For This Useful Post:

    lil_misfitss (June 22nd, 2014)

  4. #3
    Junior Member lil_misfitss's Avatar
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    Default Re: Exception in Main NullPointerException?

    Wow, it was that simple thanks!

    lil_misfit

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