How to ensure certain requirements are met in my Java Program-CodePudding

public class FileAddClient {

  public static void main(String[] args) throws FileNotFoundException {
    Scanner scanfile = new Scanner(System.in);

    System.out.println("What is the exact name of your file?");
    String doc = scanfile.next();

    Scanner scanint = new Scanner(new File(doc));

    int number1 = scanint.nextInt(), number2 = scanint.nextInt(),
    number3 = scanint.nextInt(), number4 = scanint.nextInt(),
    number5 = scanint.nextInt(), number6 = scanint.nextInt();

    int sum = number1   number2   number3   number4   number5   number6; 

    System.out.println("The sum of the numbers that typed is "   sum);

  }

}

How can I ensure that the user enters at least 2 numbers into the file and that the only data types in the file are numbers? I am not sure how to navigate through this problem. I tried making a while loop, but, unfortunately, that is not working. Any help would be appreciated.

CodePudding user response：

The method .nextInt() will throw an exception (specifically an InputMismatchException) in case the input is not an int or there is none. You can handle that exception with a try-catch block, like this:

try {
    // ... use nextInt ...
}
catch(InputMismatchException e) {
    // print error message
}

CodePudding user response：

My solution to this uses a while loop. The hasNextInt() function just checks if the input is of type int.

public class FileAddClient {

  public static void main(String[] args) throws FileNotFoundException {
    Scanner scanfile = new Scanner(System.in);

    System.out.println("What is the exact name of your file?");
    String doc = scanfile.next();

    Scanner scanint = new Scanner(new File(doc));

    int count = 0;
    int sum = 0; //total sum of numbers

    while ( scanint . hasNextInt() ) { //makes sure that the input is of type int
      count   ; //counts the number of correct inputs
      sum  = scanint.nextInt();
    }

    if ( count < 2 ) // file has one number or zero numbers
      System.out.println ( "File has less numbers than expected. Please fix it." );
    else if ( count > 6 ) //file has more than 6 numbers
      System.out.println ( "File has more than 6 numbers." );
    else // file has two numbers or more
      System.out.println("The sum of the numbers that typed is "   sum);
  }
}