Question

当我向用户询问他们在user_Radius.nextLine();处的半径时，就会发生错误，并且由于userName1.nextLine();在我运行程序时工作得很好，目前无法找到问题。

错误

线程“主”中的异常java.util.NoSuchElementException：无行在以下位置找到java.base / java.util.Scanner.nextLine（Scanner.java:1651） CircleFormulas.main（scanner.java:22）

我的代码

import java.util.Scanner;
public class CircleFormulas {

    public static void main(String[] args) {
        //Creates my constructors/variables
        //Scans for the user's name
        Scanner userName1 = new Scanner (System.in);
        //Scans for the radius the user wishes to calculate
        Scanner user_Radius = new Scanner (System.in);


        //Asks the user for their name and places their response into the userName variable
        System.out.println("What is your name?: ");
        String userName = userName1.nextLine();
        //closes the line function; locks the variable
        userName1.close();
        //Prints out a greeting for the user
        System.out.println("Hey " + userName + " How are you?");
        //Asks the user a question
        System.out.println("Now, what is the radius of the circle you'd like to calculate?");
        //Asks the user for their radius they'd like to calculate and places their response into the radius variable
        String radius = user_Radius.nextLine();
        user_Radius.close();
        //Prints out the radius of the user's circle
        System.out.println("So, the radius of your circle is: " + radius);
    }
}

Answer 1

出现错误是因为尝试重用已关闭的System.in（即使在另一个变量中声明了该变量，但仍处于关闭状态）。

您无需实例化多个扫描仪，一次执行并多次重复使用就足够了：

Scanner scanner = new Scanner(System.in);

String userName = scanner.nextLine();
String radius = scanner.nextLine();

scanner.close();

使用Java.util.scanner时出现noSuchElement错误

1 个答案: