Thread: null pointer exception error for a method calling a graphics obj help please

I am trying to get a paddleball game working and as i create my paintComponent i have it call a method from a different class and its giving me this error

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at pong.panelc.paintComponent(panelc.java:48)
I pasted the code below minus movement and listener methods and its giving me the same errors.

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionListener;
 
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
 
 
 
 
 
public class pongTest extends JPanel{
 
 
	int displayH;
	int displayW;
	int paddlex;
	panelc display;
	ballc ball;
	paddlec paddle;
 
 
 
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		pongTest obj = new pongTest();
	}
 
	pongTest()
	{
 
 
		display = new panelc();
		displayH = display.getHeight();
		displayW = display.getWidth();
		paddle = new paddlec(40,300);
		ball = new ballc(20);
 
	}
	class panelc extends JPanel
	{
	int height;
	int width;
 
	JFrame frameD;
	pongTest control;
 
 
	panelc()
	{
 
		width = getWidth();
		height = getHeight();
 
		frameD = new JFrame();
		frameD.setSize(640,480);
		frameD.setResizable(false);
		frameD.getContentPane().add(this);
		frameD.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frameD.setVisible(true);
 
 
 
	}
 
	public void paintComponent(Graphics g) 
	{
		super.paintComponent(g);
		setBackground(Color.BLACK);
		g.fillRect(0, 0, frameD.getWidth(), frameD.getHeight());
		control.draw(g);
	}
	}
	class paddlec extends JPanel //paddle class
	{
 
		int Length;
		int width;
		int positionX;
		int positionY;
		int paddleCenter;
 
 
		paddlec(int length, int positionx)
		{
 
			width = 5;
			Length = length;
			positionX = positionx;
			positionY = 30;
			paddleCenter = (positionx + (length / 2));
 
		}
 
		public void paintComponent(Graphics g)
		{
 
			g.fillRect(positionX,positionY,Length,width);
			g.setColor(Color.ORANGE);
 
		}
	}
 
	class ballc extends JPanel  //ball class
	{
 
		int size;   // size of ball
		int positionX;  // x position of ball
		int positionY;  // y position
		int movementX;  // movement speed in x direction
		int movementY;  // in y direction
		int pheight;  // display panel height
		int pwidth;  // display panel width
 
 
 
		ballc(int sizex) // constructor setting size position and display size and movement speed
		{
 
			size = sizex;
			positionX = 0;
			positionY = 0;
			movementX = (size / 4);
			movementY = (size / 4);
 
 
		}
 
		public void paintComponent(Graphics g)
		{
 
			g.setColor(Color.BLUE);
			g.fillOval(positionX, positionY, size, size);
 
		}
	}
	public void draw(Graphics g)
	{	
		if ((paddle != null) && (ball != null))
		{
		paddle.repaint();
		ball.repaint();
		}
 
	}
}

I can get the black background to show sometimes but not reliably and never with the ball or paddle.
any help is appreciated thanks in advance.

This really isn't enough code for us to debug. Can you post an SSCCE showing what you're doing?

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at pong.panelc.paintComponent(panelc.java:48)

What variable on line 48 is null when that line is executed?

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at test.pongTest$panelc.paintComponent(pongTest.java: 74)

What variable on line 74 is null when that line is executed?

What is the value of control when that line is executed? Add a println() just before line 74 and print out the value of control and g.

Are you talking about the variable: control? Have you defined it in more than one place so that the local variable shadows the class level variable?

it didn't even compile

If you want help with the errors, you will have to post the code and the full text of the error messages.