I need my Java program to ONLY accept number inputs from the scanner. So if a user enters in a letter or any special character like *&^$# ({ etc it will not crash the code and instead just print an invalid input message and end the program.

So what would I add to my code to make it numbers only, but accept spaces between the numbers? I know I could add an if else statement, but what exactly would go in there? I would like to know so I can implement this restriction in other kinds of code too. If there is a universal method to restrict input that can work with every code or at least able to make minor adjustments to match whatever code I write.

My example code:

import java.util.*;

public class NumbersOnly {

public static void main(String[] args) {

Scanner input = new Scanner(System.in);

System.out.print("Enter a number: ");

int n = input.nextInt();

if(){

*something*

System.out.println("Invalid number. Use only numerical inputs."); //After this line the code will end if the input is wrong

}else{

System.out.println(n);

}

}

}