Java扫描程序错误:线程中的异常" main" java.util.NoSuchElementException

时间:2015-10-28 20:22:10

标签: java java.util.scanner

我刚开始使用java开始我的大学课程,并继续使用Scanner课程出现此错误。

import java.util.Scanner;

public class InchConversion
{
    public static void main (String[] args)
    {   
        Double inches, centimeters;
        Scanner fromKeyboard = new Scanner(System.in);
        System.out.println("Enter Value in Inches");
        inches = fromKeyboard.nextDouble();
        centimeters = inches*2.54;
        System.out. println(inches + " inches is equal to " + centimeters + " centimeters.");
    }
}

我不断得到的错误是:

  Compiling InchConversion.java.......
-----------OUTPUT-----------
Enter Value in Inches
Exception in thread "main" java.util.NoSuchElementException
    at java.util.Scanner.throwFor(Scanner.java:862)
    at java.util.Scanner.next(Scanner.java:1485)
    at java.util.Scanner.nextDouble(Scanner.java:2413)
    at InchConversion.main(InchConversion.java:11)
[Finished in 0.8s with exit code 1]

1 个答案:

答案 0 :(得分:4)

例如,您需要使用3.0作为输入,因为您明确地告诉扫描器期望浮点值,并且在Java float中需要小数,即使它是整数。 Workouround将是:

double inches = Double.parseDouble(fromKeyboard.nextLine());

这样你告诉扫描器解析当前行上的第一个字符串值,也可以解释为double(在这种情况下,即使数字没有小数,java编译器也不关心,它在解析过程中添加它) 。因此,如果输入20,它将自动添加小数和inches = 20.0。但是如果你想要inches = 20.1,你仍然需要输入20dot1。但至少它摆脱了不直观的外星人20.0输入。

编辑:我用我的修复程序尝试了你的代码,它对我来说非常好

public static void main (String[] args) {   
    Double inches, centimeters;
    Scanner fromKeyboard = new Scanner(System.in);
    System.out.println("Enter Value in Inches");
    inches = Double.parseDouble(fromKeyboard.nextLine());
    centimeters = inches*2.54;
    System.out.println(inches + " inches is equal to " + centimeters + " centimeters.");
}

如果输入1,则输出为1.0 inches is equal to 2.54 centimeters.