import java.util.*;

public class HandleExceptionDemo {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    boolean continueInput = true;

    do {
      try {
        System.out.print("Enter an integer: ");
        int number = scanner.nextInt();

        // Display the result
        System.out.println(
          "The number entered is " + number);

        continueInput = false;
      }
      catch (InputMismatchException ex) {
        System.out.println("Try again. (" +
          "Incorrect input: an integer is required)");
      scanner.nextLine(); //为什么去掉这个会是死循环？
      }
    } while (continueInput);
  }
}

能不能说明nextLine的作用？

去掉那句nextLine，你试下程序，输入55sd，会是死循环。