Scanner, nextInt and InputMismatchException

I'm trying to read a text file and then print out the integers in a loop using the nextInt() function in Java. The text file I have is of the form:

a 2000 2
b 3000 1
c 4000 5
d 5000 6

Here is my code:

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

  String fileSpecified = args[0] + ".txt";

  FileReader fr = new FileReader(fileSpecified);
  BufferedReader br = new BufferedReader (fr);
  Scanner in = new Scanner (br);

  while (in.hasNextLine()) {
    System.out.println ("next int = " + in.nextInt());
  }
}

The error I always get is:

Exception in thread "main" java.util.InputMismatchException
           at java.util.Scanner.throwFor(Unknown Source)
开发者_开发技巧           at java.util.Scanner.next(Unknown Source)
           at java.util.Scanner.nextInt(Unknown Source)
           at java.util.Scanner.nextInt(Unknown Source)

I get this error everytime I use nextInt() in any program.

I think it will be finding the characters e.g. "a","b","c" which is a String and failing to take it as an int. You can figure this out by debugging with:

System.out.println ("next value= " + in.next());
//System.out.println ("next int = " + in.nextInt());

You could alternatively use the API guard to prevent this e.g.

if(in.hasNextInt()) {
        System.out.println ("next int = " + in.nextInt());
}

You probably want something like this instead:

while (in.hasNext()) {
    System.out.println("letter = " + in.next());
    System.out.println("integer1 = " + in.nextInt());
    System.out.println("integer2 = " + in.nextInt());
}

hasNextLine doesn't mean that the next value is an int. The input file that you posted contains e.g. "a", and that isn't an int.