获取十进制数正则表达式

Question

I am trying to create a simple program to practice parsing data. I'll show you my code then explain what I'm trying to do:

String data = "<span id=\"yfs_l84_ibm\">176.85</span>";
Pattern pattern = Pattern.compile("\\d+([.]\\d{2})?");
Matcher matcher = pattern.matcher(data);
if (matcher.find())
    System.out.println(matcher.group(1));

All I'm trying to do is print out "176.85." There will always be two numbers after the decimal place, and 1 or more numbers in front of the decimal. I don't need to worry about negative numbers, although it wouldn't hurt if my regular expression handled that. My code gets inside the if , but prints null . Is something wrong with my regular expression? Below are other regular expressions I have tried. They also print null , or never get inside the if .

1. ^[+-]?(\\d+(.?\\d+)?|.\\d+)$
2. /^\\d+.?\\d*$/
3. /\\d+.?\\d*/

Answer 1

If you wish to match numbers with the +/- as a prefix, use:

[-+]?\\d{1,4}\\.\\d{2}

And extract group 0.

Answer 2

Umm, try to change the pattern into this \\\\d+\\\\.\\\\d{2}
And matcher.group(0)
I've tried it and it worked well :)

Answer 3

其表达功能：

(\\d+([.]\\d{2})?)