java.util.NoSuchElementException 的问题：找不到行

Question

当我Scanner在 java 中获取字符时，编译器抛出：Exception in thread "main" java.util.NoSuchElementException: No line found    at java.base/java.util.Scanner.nextLine(Scanner.java:1651)    at ShoppingCartManager.getChar(ShoppingCartManager.java:37)    at ShoppingCartManager.printMenu(ShoppingCartManager.java:56)    at ShoppingCartManager.main(ShoppingCartManager.java:30)这是抛出异常的代码部分private static final Scanner scan = new Scanner(System.in);public static void main(String[] args) {    Scanner scnr = new Scanner (System.in);    System.out.println("Enter Customer's Name:");    String name = scnr.nextLine();    System.out.println("Enter Today's Date:");    String date = scnr.nextLine();    System.out.println();    ShoppingCart cart = new ShoppingCart(name, date);    System.out.println("Customer Name: " + name);    System.out.println("Today's Date: " + date + "\n");    printMenu(cart);    scan.close();}private static char getChar () {    char option;    while (true) {        try {           option = scan.next().charAt(0);           break;        } catch (Exception exc) {           continue;        }    }    return option;}public static void printMenu(ShoppingCart cart) {    while(true) {        System.out.println("MENU");        System.out.println("g - Add Guitar to cart");        System.out.println("c - Add Candy Bar to cart");        System.out.println("s - Add Shoes to cart");        System.out.println("d - Remove item from cart");        System.out.println("n - Change item quantity");        System.out.println("i - Output items' descriptions");        System.out.println("o - Output shopping cart");        System.out.println("q - Quit" + "\n");        System.out.println("Choose an option:");        char option = getChar();        if (option == 'q') {            return;        } 我该怎么办？

Answer 1

使用 Scanner 你需要检查下一行是否有 hasNext() 这样循环就变成了

while(sc.hasNext()){

str=sc.next().charAt(0);

//...

}

Answer 2

使用扫描仪时还需要检查是否有下一行，可用于hasNextLine()执行此检查。