title: Reject Non numeric characters
body: <p>Well this little thing is killing me. I am quite a rookie in Java and, have been trying every possible possibility out there and nothing seems to work.</p>
  
  <p>I just want the program to either reject non numerical strings, or ignore letters when pressed on keyboard.</p>
  
  <pre><code>import java.util.Scanner;
  
  public class practice7 {
  
  
      public static void main(String[] args) {
  
  
          System.out.println("    Wlecome to the Magellan School student assistant \n\n");
          System.out.print("Please Enter your Student ID:  ");
          Scanner sc = new Scanner(System.in);
          Scanner NS = new Scanner(System.in);
          int ID = sc.nextInt();
  
  //PRETTY SURE IT GOES HERE...
  
  //rest of program
  </code></pre>
  
  <p>I have tried all the answers given here, but every time I write letters I get this:</p>
  
  <pre class="lang-none prettyprint-override"><code>Please Enter your Student ID:  ee
  
  Exception in thread "main" java.util.InputMismatchException
      at java.util.Scanner.throwFor(Scanner.java:909)
      at java.util.Scanner.next(Scanner.java:1530)
      at java.util.Scanner.nextInt(Scanner.java:2160)
      at java.util.Scanner.nextInt(Scanner.java:2119)
      at practice7.main(practice7.java:11)
  Java Result: 1
  BUILD SUCCESSFUL (total time: 4 seconds)***
  </code></pre>