How to catch an exception if the the input is string instead of integer? It's confusing me since they used Try, Catch, Finally which looks new to me. Please enlighten me thanks.

import java.util.*;
public class ExceptionSample {
    public static void main (String[]args){
       Scanner s = new Scanner(System.in);
       int dividend, divisor, quotient;
       System.out.print("Enter dividend: ");
       dividend = s.nextInt();
       System.out.print("Enter divisor: ");
       divisor = s.nextInt();
       try {
        quotient = dividend/divisor;
        System.out.println(dividend   " / "   divisor   " = "   quotient);
       }
       catch (ArithmeticException ex) {
        System.out.println("Divisor cannot be 0.");
        System.out.println("Try again.");
       }
        finally  {
    System.out.println("Thank you.");
    }
    }
}

CodePudding user response：

It would go something like this:

Scanner s = new Scanner(System.in);

int dividend, divisor, quotient;
while (true) {
    System.out.print("Enter dividend: ");
    try {
        dividend = s.nextInt();
    } 
    catch (java.util.InputMismatchException ex) {
        System.out.println("Invalid Dividend Entry! Try again...\n"); 
        s.nextLine(); // consume the Enter Key Hit.
        continue;
    }
    break;
}
    
while (true) {
    System.out.print("Enter divisor: ");
    try {
        divisor = s.nextInt();
        if (divisor == 0) {
            throw new java.util.InputMismatchException();
        }
    }
    catch (java.util.InputMismatchException ex) {
        System.out.println("Invalid Divisor Entry! Try again...\n"); 
        s.nextLine(); // consume the Enter Key Hit.
        continue;
    }
    break;
}
    
try {
    quotient = dividend / divisor;
    System.out.println(dividend   " / "   divisor   " = "   quotient);
}
catch (ArithmeticException ex) {
    System.out.println("Divisor cannot be 0.");
    System.out.println("Try again.");
}
finally {
    System.out.println("Thank you.");
    s.close();
}

When the Scanner#nextInt() method is used and one or more alpha characters are supplied a InputMismatchException is thrown. We trap this exception and use it to our advantage for validating the numerical input.