Question

我正在创建一个程序，在交互式输入结束后打印出情况摘要（ctrl -d）。因此，它打印了交互输入后接种疫苗的儿童的平均年龄和百分比的摘要。

然而，每当我按名称：ctrl-d时，我总是收到No Line Found错误。我的编译器告诉我错误是在name = sc.nextLine（）;在while循环中，但我不知道究竟是什么导致了错误。

public static void main(String[] args) {

        String name = new String();
        int age, num = 0, i, totalAge = 0;
        boolean vaccinated;
        int numVaccinated = 0;
        double average = 0, percent = 0, count = 0;

        Scanner sc = new Scanner(System.in);

            System.out.print("Name: ");
            name = sc.nextLine();

            System.out.println("Name is \"" + name + "\"");
            System.out.print("Age: ");
            age = sc.nextInt();
            System.out.println("Age is " + age);
            System.out.print("Vaccinated for chickenpox? ");
            vaccinated = sc.nextBoolean();

            totalAge += age;
            num++;

            if(vaccinated == true)
            {
                count++;
                System.out.println("Vaccinated for chickenpox");
            }
            else
            {   
                System.out.println("Not vaccinated for chickenpox");
            }

        while(sc.hasNextLine())
        {   
            sc.nextLine();
            System.out.print("Name: ");
            name = sc.nextLine();

            System.out.println("Name is \"" + name + "\"");
            System.out.print("Age: ");
            age = sc.nextInt();
            System.out.println("Age is " + age);
            System.out.print("Vaccinated for chickenpox? ");
            vaccinated = sc.nextBoolean();

            totalAge += age;
            num++;

            if(vaccinated == true)
            {
                count++;
                System.out.println("Vaccinated for chickenpox");
            }
            else
            {   
                System.out.println("Not vaccinated for chickenpox");
            }
        }

        average = (double) totalAge/num;

        percent = (double) count/num * 100;

        System.out.printf("Average age is %.2f\n", average);
        System.out.printf("Percentage of children vaccinated is %.2f%%\n", percent);

    }
}

Answer 1

如果你问我，你没有正确地为你的循环实现退出条件。

尝试这样的事情：

String input = "";
do {
    System.out.print("Name: ");
    name = sc.nextLine();
    [... all your input parameters ...]
    sc.nextLine();
    System.out.print("Do you want to enter another child (y/n)? ");
    input = sc.nextLine();
} while (!input.equals("n"));

这样您就可以退出输入新人，而无需输入可能导致错误的奇怪命令。此外，do-while循环可帮助您减少代码，因为您不必两次使用相同的代码，即示例中Scanner sc = new Scanner(System.in);和while(sc.hasNextLine())之间的所有代码。

没有这样的元素 - 找不到行（Java）

1 个答案: