Java I/O - 如何使用扫描器从标准输入读取一个int

import java.util.Scanner;
public class Main {
  public static void main(String[] ap) {
    int val;
    try {
      Scanner sc = new Scanner(System.in);      // Requires J2SE 1.5
      val = sc.nextInt();
    } catch (NumberFormatException ex) {
      System.err.println("Not a valid number: " + ex);
      return;
    }
    System.out.println("I read this number: " + val);
  }
}