I want to show my own error to the screen insted of this ==>

Exception in thread "main" java.util.InputMismatchException
    at java.base/java.util.Scanner.throwFor(Scanner.java:964)
    at java.base/java.util.Scanner.next(Scanner.java:1619)
    at java.base/java.util.Scanner.nextInt(Scanner.java:2284)
    at java.base/java.util.Scanner.nextInt(Scanner.java:2238)

I want it like this if input enters a str or – number ==>
Please enter a valid number!
I tried this but it is not working but at least it’s working for nil or – numbers but when I enter a string nothing is working

import java.util.Scanner;
class Main {
    public static void main(String[] args){
       Scanner scanner = new Scanner(System.in);
       int firstNum = scanner.nextInt();
       int secondNum = scanner.nextInt();
       if(secondNum == 0 || firstNum == 0){
           System.out.print("Please enter a valid number!");
       } else if(firstNum > 0 && secondNum > 0){
           int add = Math.addExact(firstNum,secondNum);
           System.out.print(add);
       } else{
           System.out.print("Please enter a valid number!");
       }
    }
}