NullPointerException Using PrintStream or PrintWriter

Question

Here is the code that I am using. I am taking the output of a program and trying to write that output to a file. When outputting to the file I receive a null pointer exception that I don't know why I am getting. I am using PrintStream here but I also tried using PrintWriter and I got the same error. If I uncomment the System.out.println statement the first line is printed to the console window, but then when it tries to print that line to the file I apparently get the NullPointerException. Can anyone help? Thank you. Here is that bit of code.
p = r.exec(myprogram);
                              InputStream in = p.getInputStream();
                              BufferedReader br = new BufferedReader(new InputStreamReader(in));
                              String line = null;
                              try
                                   PrintStream outFile = new PrintStream(new FileOutputStream("testresults.txt"));
                              catch(FileNotFoundException fe)
                                   System.out.println("File not found: " + fe);
                              while ((line = br.readLine()) != null)
                                   //System.out.println(line);
                                   outFile.println(line);
                              p.waitFor();

Answer 1

I can tell you exactly why... Here's an example
public static void aMethod() {
  String s = "Foo";
    String s = "Bar";
  System.out.println(s);
}The value output is "Foo" because the 's' declared in the parenthesis is a different variable in it's own scope.
Your code does something similar when you did the following
try {
  PrintStream outFile = new PrintStream(new FileOutputStream("testresults.txt"));
} catch(FileNotFoundException fe) {
  System.out.println("File not found: " + fe);
}This declares a variable in the scope of the try block and assigns a reference to a new PrintStream object. However this variable ceases to exist immediately following the closing parenthesis of the catch block.
Since your code compiles you must, further up have already declared outFile so I would change the code to
try {
  outFile = new PrintStream(new FileOutputStream("testresults.txt"));
} catch(FileNotFoundException fe) {
  System.out.println("File not found: " + fe);
  outfile = null;
}Note that this means if the exception occurs, outFile will be null. You need to decide what action to take in this situation.
Hope that helps - now put up your Dukes... ;)