解析数字时出现NumberFormatException

Question

String str="123456.7855456677";
ParsePosition parsePosition = new ParsePosition(0);
NumberFormat numberFormat=new DecimalFormat();
Number number=numberFormat.parse(str, parsePosition);

if(parsePosition.getIndex()!=str.length())
{
    throw new IllegalArgumentException();
}

numberFormat.setMaximumFractionDigits(2);
numberFormat.setRoundingMode(RoundingMode.HALF_UP);
double value=Double.parseDouble(numberFormat.format(number));
System.out.println(value);

The value of the String type variable str in this segment of code can be any dynamic value, assuming a user is free to input any string.

The Double.parseDouble() method on the second last line causes the java.lang.NumberFormatException to be thrown.

Removing the line numberFormat.setMaximumFractionDigits(2); and setting a RegEx to the overloaded constructor of the DecimalFormat class instead as usual like,

NumberFormat numberFormat=new DecimalFormat("#.##");

suppresses the exception.

So, why doesn't it work otherwise?

Answer 1

如果你可以调试代码然后检查这行numberFormat.format(number)放置它给出一个包含可能成为异常原因的逗号的数字，检查这个123,456.79并且这个逗号不应该在那里...希望这会有帮助。

Answer 2

Exception in thread "main" java.lang.NumberFormatException: For input string: "123,456.79"在双Exception in thread "main" java.lang.NumberFormatException: For input string: "123,456.79"数字的字符串表示形式内不能有逗号。