JAVA: Trouble understanding how to work with input files

Question

I am new to JAVA and this forum and am trying to figure out an issue with a project that classifies triangles from three sides given in a file. The file can be multiple different lines (multiple triangles), lines must start with '#' to be considered valid by the program, and can have superfluous data of varying types after the three sides are listed. For reference here is a sample input file and the corresponding output file that should be made when the program runs. input/output reference. I feel pretty confident in the majority of my program but the specific issue i'm having is dealing with the input file in my main method. I don't understand a) how to get the program to recognize only lines starting with '#' as valid input. b) how to get to the next Scanner token after '#' and assign those three to sides 1-3 only if they are integers (they don't necessarily have to be). c) how to assign the remaining data after the sides, if there is any, to a String variable. If there are any helpful Scanner methods that you know of that can assist me I would be greatly appreciative. Reading through the JAVA API is still Greek to me. The biggest thing is if there is a method that returns what the data type of the current token is, I keep getting InputMismatchException from trying to assign non-integers to my sides. Finally here is my main method that keeps plaguing me. Again thank you for any insight you can provide.

public static void main (String[] args) throws FileNotFoundException, IOException
    {
        String input, output;
        int side1 = 0, side2 = 0, side3 = 0, lineCounter = 1;
        String irrelevant;
        File inputFile;
        Scanner inputRead = null;

        System.out.println("Please choose the .txt file you would like to use for triangle side input.");
        input = fileSelect();

        System.out.println("Please choose the .txt file you would like to use as the program output file.");
        output = fileSelect();

        FileWrite outputFile = new FileWrite();

        outputFile.fileCreate(output);

        inputFile = new File(input);

        try
        {
            inputRead = new Scanner(inputFile);
        }
        catch (FileNotFoundException e)
        {
            System.out.println("No file or unsupported file found: Please choose another input file.");
            input = fileSelect();
        }

        while (inputRead.hasNextLine())
        {
            String line = inputRead.nextLine();
            while (line != null)
            { 
                if(inputRead.hasNext("#"))
                {
                    side1 = inputRead.nextInt();
                    side2 = inputRead.nextInt();
                    side3 = inputRead.nextInt();
                    irrelevant = inputRead.next();

                    areaCalc(side1, side2, side3, lineCounter, output);
                }
                lineCounter ++;
            }
        }
        if (!inputRead.hasNext())
        {

        }

        inputRead.close();
    }  

Answer 1

How about doing line parsing like below

try {
             String content[] = line.split(" ");
            if(content.length > 3) {
                 if(content[0].equals("#")) {
                   int side1 = Integer.valueOf(content[1]);
                   int side2 = Integer.valueOf(content[2]);
                   int side3 = Integer.valueOf(content[3]);
                   if(side1 > 0 && side2 > 0 && side3 > 0) {
                      areaCalc(side1, side2, side3, lineCounter, output);
                  }
               }
            }
       }catch(NumberFormatException e){}