Null Pointer Exception Trying to Read File?

Question

I get a Null Pointer Exception when I try to perform the read hex2.txt, which i know exists and is in the same folder as this java file. Anyone see where my problem is?
<code>
import java.io.*;
public class BytesToZeros
          int count = 0;
          int[] data;
          public static void main (String[] args)
                    BytesToZeros btz = new BytesToZeros();
          public BytesToZeros()
                    this.readFile();
                    this.writeFile();
          private void readFile ()
                    try
                              FileInputStream fis = new FileInputStream("hex2.txt");
                              BufferedInputStream bis = new BufferedInputStream(fis);
                              boolean eof = false;
                              while (!eof)
                                        int input = bis.read();
                                        if (input == -1)
                                             eof = true;
                                        else
                                             data[count] = input;
                                             count++;          
                              bis.close();
                    catch (IOException e)
                              System.err.println("Error Reading File: " + e.getMessage());
                              count = 0;
          private void writeFile ()
                    String zeros;
                    try
                              FileOutputStream fos = new FileOutputStream("hex2.txt");
                              BufferedOutputStream bos = new BufferedOutputStream(fos);
                              for (int i=0; i<data.length; i++)
                                        bos.write(0);
                              bos.close();
                    catch (IOException e)
                              System.err.println("Error writing file: " + e.getMessage());
</code>

Answer 1

Doesn't the stack trace you get show which line it was thrown from?
That should tell you where the problem is.
It's weird to do a file read and a file write in the constructor like that. It would make somewhat more sense to do
public static void main (String[] args) {
  BytesToZeros btz = new BytesToZeros();
  btz.readFile();
  btz.writeFile();
}Although I realize this is just a test.
Finally, to quote code use square brackes around the code tags:
&#91;code]&#91;/code]