CODEWITHSUNDEEP
javadouble
Magpie
Magpie

Reputation: 627

How to get around an InputMisMatchException in java

I have a file that I put some numbers into but then I decided I wanted to label the numbers with a name for each one, like so: 

A = 1 2 3
B = 3 4 5
C = 6 7 8

This caused an exception to be thrown. I want to know how I can workaround this so the scanner 'ignores' all but the numbers unless I tell it otherwise.

Can anyone help?

EDIT:

Also, I already know what is causing the exception. I am using next.Double(); to pick out the numbers in the file.

public static void readFile() throws IOException, FileNotFoundException {

    String fileName = "vectors.txt";


    // Reference the file using the the BufferedReader object
    BufferedReader input = new BufferedReader(new FileReader(fileName));    

    //scanner to scan through file 
    Scanner token = new Scanner(input);

    double fileX = token.nextDouble();
    double fileY = token.nextDouble();
    double fileZ = token.nextDouble();

    vecA = new Vector3D(fileX,fileY,fileZ);

    fileX = token.nextDouble();
    fileY= token.nextDouble();
    fileZ = token.nextDouble();

    vecB = new Vector3D(fileX, fileY, fileZ);

    fileX = token.nextDouble();
    fileY= token.nextDouble();
    fileZ = token.nextDouble();

    //initialize vecC using double values from third line of file
    vecC = new Vector3D(fileX, fileY, fileZ);


    //close file 
    input.close();


}

Upvotes: 1

Views: 886

Answers (3)

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726479

You cannot make the scanner ignore input automatically, but you can write code to skip input yourself until you see that a double is available:

while (!scanner.hasNextDouble()) {
    scanner.next();
}
double d = scanner.nextDouble();

If you need to put this code in multiple places, you can wrap it in a function:

private static double skipAndGetDouble(Scanner scanner) {
    while (scanner.hasNext() && !scanner.hasNextDouble()) {
        scanner.next();
    }
    return scanner.hasNextDouble() ? scanner.nextDouble() : Double.NaN;
}

Upvotes: 3

Hovercraft Full Of Eels
Hovercraft Full Of Eels

Reputation: 285405

You need to parse the text that makes sense for the data being scanned. So in your case, you have lines that repeat the basic type of information held -- meaning use a loop -- don't repeat code unnecessarily. In pseudocode

create a Scanner object read the file, say called fileScanner
while still lines to be read (fileScanner.hasNextLine())
  read line with fileScanner using .nextLine()
  Create a new Scanner object, lineScanner to get tokens in line.
  Use lineScanner to get `next` String via `.next()` and store
  Use lineScanner to get `next` String via `.next()` (the `=`) and ignore
  Use lineScanner to get 3 doubles.
  close line scanner
  Store all info in object and place in ArrayList or some other collection
end while
close fileScanner

Upvotes: 0

NickO
NickO

Reputation: 741

If you want to be very fancy, and come up with an over-kill solution, try changing the scanner's delimiter. Check out the API here.

Upvotes: 0

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