java - 调用方法后出现 NoSuchElement 异常

Question

对于一个类，我必须创建一个程序，该程序有一个菜单，用户可以根据自己的选择从菜单中选择运行某些方法。我遇到的问题是在我调用我的方法之后，程序在第 30 行抛出 NoSuchElement 异常(当我将代码粘贴在下面时，它是第 26 行，它显示了 Selection = console.nextInt())，而它应该允许用户再次从菜单中选择一个选项。有人知道为什么会发生这种情况吗？

import java.util.*;
public class PartB {

public static void main(String[] args) {
    Scanner console = new Scanner(System.in);
    String pinNum;
    int selection = 0;
    boolean pin;

    System.out.print("Enter pin: ");

    pinNum = console.next();

    pin = check_pin(pinNum);

    if (pin == false) {
        System.out.print("Thank you for using the menu system. Goodbye");
    }


        while (selection != 4 && pin==true) {

        System.out.printf("%nPlease select a number from the menu below %n1: Wage "
            + "Calculator 2: Tip Calculator 3: Grocery Discount 4: Exit %n");

        selection = console.nextInt();

        if (selection == 1) {
            calc_wages();
        } else if (selection == 2) {
            calc_tip();
        } else if (selection == 3) {
            System.out.print("We haven't gotten this far yet");
        } else if (selection == 4){
            System.out.print("Thank you for using the program.");
            break;
        } else {
            System.out.print("There is no option for what you entered. Try again");
        }
            selection = 0;
        }

    console.close();
}//main

Answer 1

if(console.hasNextInt()){
  selection = console.nextInt();
}

hasNextInt() 将确保在使用 nextInt() 读取流之前有一个要从流中读取的整数。否则，如果流已经耗尽，您可能会收到 NoSuchElementException。