Java.lang.NullPointerException.... please help.

Question

I have been trying to figure out what is wrong with my code, but I have not had any luck. For this program, I used a package called PNGEncoder located here
http://catcode.com/pngencoder/
There is a sample code that I tried to follow.
My code is as follows
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.util.*;
import java.io.*;
import com.keypoint.*;
public class TryShapes extends Frame{
     private int width;
     private int height;
     Image myImage = null;
     private String fileName = "";
     //private int filter = 0;
     //private int compressionLevel = 1;
     //boolean encodeAlpha;
     // Main entry point
public static void main(String[] args) {
          TryShapes tryShapes =new TryShapes(args[0]);
     public TryShapes(String fileName) {
          System.out.println("This program saves image into file internally.");
          this.fileName = fileName;
          processDrawingFile();
          saveImage();
private void processDrawingFile(){
     String Instr = null;
BufferedReader in;
String fileLocation = "c:\\Drawing files" + File.separator + fileName;
System.out.println("in start of process file");
int x, y, r, recWidth, recHeight, x2, y2;     
// read in file contents
try{
in = new BufferedReader(new FileReader(fileLocation));
//System.out.println("fileLocation");
Instr = in.readLine(); // the first line of files are titles, skip these
System.out.println(Instr);
Instr = in.readLine(); // this is the first line of data (the width & height of bitmap)
System.out.println(Instr);
StringTokenizer st = new StringTokenizer(Instr, "\t");
String s = st.nextToken();
this.width = Integer.parseInt(s);
String s2 = st.nextToken();
          this.height = Integer.parseInt(s2);
          System.out.println("width is " + width + " & height is " + height);
          myImage =createImage(width, height);
          System.out.println("after createImage");
Graphics g;
g = myImage.getGraphics();
System.out.println("just after myImage is set to getGraphics");
while(Instr != null){                 
     Instr = in.readLine(); // read all subsequent lines (elements of the drawing)
     System.out.println(Instr);
.... and so forth... I used printlines to determine where the program broke and it appears to stop printing after myImage.getGraphics()
you're help would be much appreciated

Answer 1

how do i determine if the createImage is not doing what it is suppose to? I'm pretty sure I declared it correctly... java api has
public Image createImage(int width,
int height)Creates an off-screen drawable image to be used for double buffering.
Parameters:
width - the specified width.
height - the specified height.
Returns:
an off-screen drawable image, which can be used for double buffering.
and the arguments are integers... what else could be wrong?