Thread: Graphics class NullPointerException Initialize Graphics Class??

I am creating a program for my final in an AP computer science class. My idea was simple: create a program that drops "meteors" and you have to dodge them with your mouse. I wrote the whole program, and then ran it and got a NullPointerException, because I did not use the Graphics class right or something. I am a good programmer, but I am not familiar at all with graphics of any kind, and the Graphics class looked easy to use, but I am not very good at it. I am trying to stay away from the JPanel/ javax.swing because I have absolutely no idea how to use them. Please help me.
(Note: Code is commented and pretty self explanatory)

got a NullPointerException

Can you post the full text of the error message and the code that goes with it.
I prefer NOT to down load .doc files.
Post the code so it can be easily read.

//Meteor.java
import java.applet.*;
import java.awt.*;
public class Meteor {
	//Problem
	Graphics g;
	//Randomize x coordinate of meteor
	private int randomNum = (int)(Math.random() * 250);
	private int mRadius;
	private int y = 0;
    private final int X = randomNum;
	public Meteor(int radius, Graphics g){
		mRadius = radius;
		g.setColor(Color.white);
		g.fillOval(randomNum, y, 2 * radius, 2 * radius);
	}
	public void fall(Graphics g){
		//draw over old meteor
		g.setColor(Color.black);
		g.fillOval(randomNum, y, 2 * mRadius, 2 * mRadius);
		//draw new meteor
		g.setColor(Color.white);
		y+=5;
		g.fillOval(randomNum, y, 2 * mRadius, 2 * mRadius);
	}
	//Getters
	public int getX() {
		return X;
	}
	public int getY() {
		return y;
	}
	//Test for if meteor is out of screen
	public boolean isOutOfScreen(){
		//250 is a random number I chose- its the applet windows length
		if(this.getY() > 250){
			return true;
		}
		else{
			return false;
		}
 
	}
 
}

//Player.java
import java.awt.*;
import java.applet.Applet;
import java.awt.Event;
public class Player {
	//Problem
	Graphics g;
	private int mouseXPosition, mouseYPosition;
	public Player(Graphics g){
		//get your mouse position and draw a red circle around it
		mouseXPosition = getMousePositionX();
		mouseYPosition = getMousePositionY();
		g.setColor(Color.red);
		g.fillOval(mouseXPosition,mouseYPosition, 20, 20);
	}
	public int getMousePositionX() {
		PointerInfo a = MouseInfo.getPointerInfo();
        Point b = a.getLocation();
        int x = (int) b.getX();
        return x;
	}
	public int getMousePositionY() {
		PointerInfo a = MouseInfo.getPointerInfo();
        Point b = a.getLocation();
        int y = (int) b.getY();
        return y;
	}
	//updates where the circle around your mouse is
	public boolean mouseMove(Event e, int x, int y, Graphics g){
		if (getMousePositionX() != mouseXPosition || getMousePositionY() != mouseYPosition){
			g.setColor(Color.black);
			g.fillOval(mouseXPosition,mouseYPosition, 20, 20);
			mouseXPosition = getMousePositionX();
			mouseYPosition = getMousePositionY();
			g.setColor(Color.red);
			g.fillOval(mouseXPosition,mouseYPosition, 20, 20);
			return true;
		}
		else{
			return false;
		}
 
	}
}

//World.java
import java.applet.*;
import java.awt.*;
public class World {
	Graphics g;
	Meteor meteor = new Meteor(10, g);
	Player player = new Player(g); 
	boolean isCollide;
	private int score = 0;
	//////////////////////////////////
	//Test for Collision//////////////
	/////////////////////////////////
	public boolean collision(){
		int pX = player.getMousePositionX();
		int pY = player.getMousePositionY();
		int mX = meteor.getX();
		int mY = meteor.getY();
		if(pX > mX - 5 && pX < mX + 5){
			if(pY > mY - 5 && pY < mY + 5){
				isCollide = true;
			}
		}
		else{
			isCollide = false;
		}
		return isCollide;
	}
	////////////////////////
	//Increment score by 10
	////////////////////////
	public void scoreAdd(){
		if (!(collision())){
			score += 10;
		}
		else{
			score = score;
		}
	}
	///////////////////////
	public int getScore(){
		return score;
	}
 
}

//MeteorDodger.java
//Driver Class
import java.awt.*;
import java.applet.*;
import java.util.ArrayList;
public class MeteorDodger extends Applet{
	Graphics g;
	static Event e;
    public void init(){
    	g.setBackground(Color.black);
    }
    public void paint(Graphics g){
    	Player player = new Player(g);
		World world = null;
		g.drawString("Score: " + world.getScore(), 0, 500);
    }
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Graphics g;
		//attempt to innitialize???
		g = g.getGraphics();
		Player player = new Player(g);
		World world = null;
		ArrayList<Meteor> listMeteors = new ArrayList<Meteor>();
		while (!(world.collision())){
			listMeteors.add(new Meteor(10,g));
			for(int i = 0; i < listMeteors.size(); i++){
				listMeteors.get(i).fall(g);
				if((listMeteors.get(i).isOutOfScreen())){
					listMeteors.remove(i);
				}
			}
			world.scoreAdd();
			//Disregard. not completed yet: test for is mouse move
			if((player.mouseMove(e, player.getMousePositionX(), player.getMousePositionY(), g))){
				player.mouseMove(e, player.getMousePositionX(), player.getMousePositionY(), g);
			}
		}
	}
 
}

thank you so much copeg. ill add that. will I need to take all the drawOval calls out of the various constructors and put them in that override or can they remain there, just slightly altered? if the latter is true, will I have to incorporate some sort of JPanel code to the fillOval? what will be the new call if so?