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[英]Exception in thread “main” java.util.NoSuchElementException Scanner error
[英]Java Scanner Error: Exception in thread “main” java.util.NoSuchElementException
我刚刚开始使用Java开设大学课程,并且在Scanner类中始终遇到此错误。
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]
例如,您需要使用3.0作为输入,因为您明确告诉扫描程序要使用float值,并且在Java中float需要十进制,即使它是整数。 Workouround将是:
double inches = Double.parseDouble(fromKeyboard.nextLine());
这样,您告诉扫描程序解析当前行上的第一个String值,该值也可以解释为double值(在这种情况下,即使数字没有小数,Java编译器也不在乎,它会在解析过程中将其添加)。 因此,如果输入20,它将自动将小数和inches = 20.0
加inches = 20.0
。 但是,如果您希望inches = 20.1
,则仍然必须输入20dot1。 但是至少它摆脱了不直观和陌生的20.0输入。
编辑:我尝试用您的修复程序的代码,它对我来说很好
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.
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