import java.awt.Graphics;
import java.awt.Image;

import javax.swing.JApplet;

/*
 * Created on Nov 13, 2004
 *
 */

public class Sprite extends JApplet {
    int xPos;
    int yPos;
    private int xVelocity;
    private int yVelocity;
    int width;
    int height;
    private Image myImage;
    private Box bound;

    public Sprite(String filename, int myWidth, int myHeight) {
        width = myWidth;
        height = myHeight;
        xPos = 0;
        yPos = 0;
        myImage = getImage(getDocumentBase(), filename);
    }
    public void setPosition(int newXpos, int newYpos){
        xPos = newXpos;
        yPos = newYpos;
    }
    public void processVelocity(){
        xPos += xVelocity;
        yPos += yVelocity;
    }
    public boolean collision(Sprite other){
    	int x0 = xPos + bound.x1;
    	int y0 = yPos + bound.y1;
    	int x1 = xPos + bound.x2;
    	int y1 = yPos + bound.y2;
    	
    	int x2 = other.xPos + other.bound.x1;
    	int y2 = other.yPos + other.bound.y1;
    	int x3 = other.xPos + other.bound.x2;
    	int y3 = other.yPos + other.bound.y2;

    	return !(x1<x2 || x3<x0 || y1<y2 || y3<y0);
    }
    public void blit(Graphics g){
        g.drawImage(this.myImage, xPos, yPos, width, height, this);
    }
    public void blit(Graphics g, int _xpos, int _ypos){
        g.drawImage(this.myImage, _xpos, _ypos, width, height, this);
    }
                              
}

[source lang = "Java"]
public class Box {
    public int x1;
    public int y1;
    public int x2;
    public int y2;
    public int width;
    public int height;

    public Box(Sprite dude) {
        x1 = dude.xPos;
        y1 = dude.yPos;
        x2 = x1 + dude.width;
        y2 = y1 + dude.height;
        width = dude.width;
        height = dude.height;
    }
}

import java.applet.*;
import java.awt.*;

public class Implementation extends Applet
{
   Sprite test;
   public void init()
   {
     test = new Sprite("ganesha.jpg", 234, 343);
   }
  public void paint (Graphics g)
  {
    g.drawString("Hello World!", 50, 25);
  }
}

java.lang.NullPointerException
	at java.applet.Applet.getDocumentBase(Unknown Source)
	at Sprite.<init>(Sprite.java:26)
	at Implementation.init(Implementation.java:9)
	at sun.applet.AppletPanel.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)
java.lang.NullPointerException
	at java.applet.Applet.getDocumentBase(Unknown Source)
	at Sprite.<init>(Sprite.java:26)
	at Implementation.init(Implementation.java:9)
	at sun.applet.AppletPanel.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)

public Sprite(String filename, int myWidth, int myHeight, Applet myApplet) {        width = myWidth;        height = myHeight;        xPos = 0;        yPos = 0;        myImage = getImage(myApplet.getDocumentBase(), filename);    }

import java.applet.*;import java.awt.*;public class Implementation extends Applet{   Sprite test;   public void init()   {     test = new Sprite("ganesha.jpg", 234, 343, this);   }  public void paint (Graphics g)  {    g.drawString("Hello World!", 50, 25);  }}