Print to screen OR file problem, need help please.

Question

Hiyo!, im doing a certain program the way to Uni wants me to do it so im using a textFile jar file for all the reading writing etc, i know its not standard java but thats not what im having trouble with.
Im trying to make a prog that will print its results to screen if the only augument on the command line is the file to read from eg.( java ProgramThree input.txt ).
but if two arguments are written on the command line eg.( java ProgramThree input.txt output.txt ) then it
will print the results to the file (output.txt) and not display to screen.
I know that its just that ive messed up a couple of the "args.length" statments in main() , but my brain gets confused easy :[
Any help would be sweet. Thanks.
class ProgramThree
        public static String calc(String line)
            String type[] = {"Valid Isosceles","Valid Equilateral","Valid Scalene","Invalid"};
            String result = null;
          int s1 = 0;
          int s2 = 0;
          int s3 = 0;
          try
               StringTokenizer st = new StringTokenizer(line);
               s1 = Integer.parseInt(st.nextToken());
               s2 = Integer.parseInt(st.nextToken());
               s3 = Integer.parseInt(st.nextToken());
          catch (Exception e) {e.printStackTrace();}
          if ((s1+s2>s3)&&(s1+s3>s2)&&(s2+s3>s1))
               if((s1==s2)||(s1==s3)||(s2==s3))
                    if((s1==s2)&&(s1==s3))
                         result = type[1];
                    else
                         result = type[0];
               else
                    result = type[2];
          else
               result = type[3];
          return result;
        public static void printScreen(String result)
          System.out.println("\nTriangle is: " +result+ "\n");
        public static void main(String args[])
          String line = null;
          String result = null;
                if(args.length > 2)
                  System.out.println("Too many Filenames Given!");
                  System.exit(1);
                textFile inFile = new textFile(args[0], 'r');
                textFile outFile = new textFile(args[1], 'a');
          while(!inFile.EOF())
               line = inFile.readLine();
               if(line == null)
                    break;
               result = calc(line);
               if(args.length == 0)
                    printScreen(result);
               else
                             outFile.writeLine(result);
                    System.out.println("\nResults written to file.");
          inFile.closeFile();
          outFile.closeFile();
          return;
}

Answer 1

Thanks for your reply neil!
But im not to sure how I would impliment your code into my program :0
The code that I posted before is throwing an arrayOutOfBounds exception at the line
inFile = new textFile(args[0], 'r');
outFile = new textFile(args[1], 'a'); <-----------Here
This happens if I enter none or one auguments on the command line :/
But if I enter two auguments it works fine and writes to file..
I know its because when there is one augument on the command line (or none at all) it opens to outFile for nothing, because its printing to screen?
The thing is i dont know how to fix this :[
-thanks