无法使循环正确工作

Question

我试图使一个计算器与一定的输入，是输入像+5或/10 2。当我编译并运行它时，我会得到以下错误：

线程“main”java.util.NoSuchelementException
在java.util.scanner.throwfor(Scanner.java:907)
在java.util.scanner.next(Scanner.java:1416)
在calc.main(calc.java:11)

import java.util.Scanner;
public class calc {

public static void main(String[] args) {
    Scanner input = new Scanner( System.in );
        String calc;
        double num1;
        double calcdu = 0.0;
        double num2;
        while ( true ) {
            calc = input.next();
            num1 = input.nextDouble();
            num2 = input.nextDouble();

            if (calc.equals("+"))
            { 
                    calcdu= num1 + num2;
                    System.out.printf("%.2e %s %.2e %c %.2e\n", num1, "+", num2, '=', calcdu);
            }       

            if (calc.equals("/"))
            {   
                calcdu=num1/num2;
                System.out.printf("%.2e %s %.2e %c %.2e\n", num1, "/", num2, '=', calcdu);
            }

            if (calc.equals("-"))
            {   
                    calcdu=num1-num2;
                    System.out.printf("%.2e %s %.2e %c %.2e\n", num1, "-", num2, '=', calcdu);
            }       
            if (calc.equals("*"))
            {   
                    calcdu=num1*num2;
                    System.out.printf("%.2e %s %.2e %c %.2e\n", num1, "*", num2, '=', calcdu);
            }
            if (calc.equals("%"))
            {   
                    calcdu=num1%num2;
                    System.out.printf("%.2e %s %.2e %c %.2e\n", num1, "%", num2, '=', calcdu);
            }

}}}

Answer 1

您在扫描程序上调用next()而没有检查hasnext()

while(input.hasNext())
{
 num1 = Double.parseDouble(input.nextDouble());
            num2 = Double.parseDouble(input.nextDouble());

......//further code