NoSuchElementException不解决

Question

我是Java的新手。从Java开始练习它的完整参考。 现在发生异常，我已经完成了此链接中的所有建议 https://stackoverflow.com/questions/13729294/nosuchelementexception-with-java-util-scanner#=

但我仍然得到错误。我正在使用Eclipse IDE

代码在这里。

import java.util.Scanner;

public class Calculater {
    /**
     * @param args
     */
    public static void main(String[] args) {
        Scanner IO=new Scanner(System.in);
        char input;
        System.out.println("Please Enter \n '+' for Addition  \n'-' for Subtraction \n '*' for Multiplication \n '/' for Division = ");
        input=IO.next().charAt(0);
        if(input=='+' || input=='-' || input=='*' || input=='/') {
            IO.close();
        } else {
            System.out.println("You entered Wrong operater!!!!!!!!");
            Calculater.main(args);
        }
        if(input == '+') {
            Calculater cal=new Calculater();
            cal.addition();
        }
    }

    public  void addition(){
        Scanner IO= new Scanner(System.in);
        double num1,num2,num3;
        char choice;
        System.out.println("Please Enter 1st Number = ");
        if(IO.hasNextDouble()) {
            num1=IO.nextDouble();
        } else {
            num1=0;
        }
        System.out.println("Please Enter 2nd Number =  ");
        if(IO.hasNextDouble()) {
            num2=IO.nextDouble();
        } else {
            num2=0;
        }
        num3=num1+num2;
        System.out.println("After Addtion Answer is = "+num3);
        System.out.println("Do You Want more Calculation Enter 'Y' for Yes and any key for No = ");
        choice=IO.next().charAt(0);
        IO.close();
        if (choice == 'Y') {
            String[] args = {};
            main(args);
        } else {
            System.exit(0);
        }
    }
}

OutPut是这个

   Please Enter 
   '+' for Addition  
   '-' for Subtraction 
   '*' for Multiplication 
   '/' for Division = 
                +
    Please Enter 1st Number = 
    Please Enter 2nd Number =  
    After Addtion Answer is = 0.0
    Do You Want more Calculation Enter 'Y' for Yes and any key for No = 
    Exception in thread "main" java.util.NoSuchElementException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at Calculater.addition(Calculater.java:87)
at Calculater.main(Calculater.java:37)

Answer 1

（从评论中移出）

问题似乎是关闭Scanner然后尝试阅读它。只需删除那些天真的IO.close来电，然后将其关闭，直至程序结束。

Answer 2

我可以收集到的是它是在输入之前尝试读取加/减的数字，并且在继续申请之前不再等待输入。

例如，您正在使用.close();方法关闭输入流，然后才能读取其他内容，因此请尝试删除这些代码行，直到应用程序结束。

申请表的输出：

Please Enter 
 '+' for Addition
+
Please Enter 1st Number = 
Please Enter 2nd Number =  
After Addtion Answer is = 0.0
Do You Want more Calculation Enter 'Y' for Yes and any key for No = 
Exception in thread "main" java.util.NoSuchElementException
    at java.util.Scanner.throwFor(Scanner.java:907)
    at java.util.Scanner.next(Scanner.java:1416)
    at zip.Calculater.addition(Calculater.java:85)
    at zip.Calculater.main(Calculater.java:40)
Java Result: 1
BUILD SUCCESSFUL (total time: 1 second)

使用IO.next();尝试不同的方法，在转移到下一行代码之前，会等待输入。

我会建议这样的事情：

package zip;

import java.util.Scanner;

public class Calculater
{
    static Scanner console = new Scanner(System.in);

    public static void main(String[] args)
    {
        System.out.println("Enter \'+\' for addition.");

        if(!console.next().equals("+"))
        {
            System.out.println(console.next() + "is not an accepted character.");
            System.exit(0);
        }
        else
        {
            System.out.println("Enter first number followed enter then the second number followed by enter.");
            String f = console.next();
            String s = console.next();

            int fI = Integer.parseInt(f);
            int sI = Integer.parseInt(s);

            System.out.println(fI + " + " + sI + "=" + (fI + sI));
        }

    }
}

输出：

Enter '+' for addition.
+
Enter first number followed enter then the second number followed by enter.
56
23
56 + 23=79
BUILD SUCCESSFUL (total time: 7 seconds)

也尽量不要使用大写字母作为对象名称，在开头使用大写字母表示对象名称，在开头使用小写字母作为对象名称。