Integer.parseInt（）问题

Question

I'm having a bit of a problem trying to get my code to work. I am working on a project for my computer science class, and I have to get my program to read the file and perform some math. When I tried doing this, the code was not working. I then checked with a friend who wrote the exact same code, and it did not work.

The input .txt file that the program reads looks like this: 2/3,4/5 -1/6,2/4 1/1,1/1

The code I have written looks like this:

import javax.swing.JFileChooser;

import java.util.*;

public class ProjectTest
{

    public static void main(String[] args) throws Exception
    {           

        JFileChooser chooserRational = new JFileChooser();
        int returnValRational = chooserRational.showOpenDialog(null);
        if(returnValRational == JFileChooser.APPROVE_OPTION)
        {
            System.out.println("You chose to open this file: " + chooserRational.getSelectedFile().getName());

            Scanner input = new Scanner(chooserRational.getSelectedFile());

            while(input.hasNext() == true)
            {
                String line = input.nextLine();
                String[] output = line.split(",");
                String[] output1 = output[0].split("/");
                String[] output2 = output[1].split("/");

                String a = output1[0];
                String b = output1[1];
                String c = output2[0];
                String d = output2[1];

                int int1 = Integer.parseInt(a);
                int int2 = Integer.parseInt(b);
                int int3 = Integer.parseInt(c);
                int int4 = Integer.parseInt(d);

                System.out.println(int1 + " " + int2 + " " + int3 + " " + int4);


            }
            input.close();
        }
    }
}

When I output just the Strings a, b, c, and d, the code works perfectly fine and outputs the values perfectly. When the code sees Integer.parseInt(a) , however, it gives me an error that looks like this:

Exception in thread "main" java.lang.NumberFormatException: For input string: "?2"
  at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
  at java.lang.Integer.parseInt(Integer.java:580)
  at java.lang.Integer.parseInt(Integer.java:615)
  at ProjectTest1.main(ProjectTest1.java:33)

Any help would be greatly appreciated.

Answer 1

Because your data file contains an UTF-8 BOM .

You have two alternatives: edit your source data file to remove the BOM, or you can add some code to deal with the BOM. For the first option use Notepad++ and remove the BOM. For the second alternative:

Scanner input = new Scanner(chooserRational.getSelectedFile());

if (input.nextByte() == 0xFE) {
  input.nextByte();
  input.nextByte();
} else {
  input = new Scanner(chooserRational.getSelectedFile());
}

Answer 2

You should replace

String line = input.nextLine();

with

String line = input.next();

since you have multiples groups of data on the same line.

Edit :

I ran your code and did not get the same exception as you. I had a NumberFormatException due to the nextLine call, I now fixed it and it runs with no error. I think like the others that you have an encoding problem. Search on the internet how to display invisible characters on your preferred text editor.