How to get integers from a specific string using regexp?-CodePudding

I have some sample text

# HELP aaasd asdads
# TYPE ASDA dasdas
goodmetric_total{"camel-1"} 777.0
# HELP qqq www
# TYPE eee rrr
badmetric_total{"camel-1"} 888.0

I will need to get numbers from a specific string. Using String.format, I will substitute the values I need. For example goodmetric_total.

How do I write a regexp to get only a numerical value? At the moment, I have solutions for searching string first.

^goodmetric. \d

And already in this line look for numbers.

I think you can do all this in one operation. Thanks!

CodePudding user response：

You can use a regex approach with

(?m)^goodmetric.*\h(\d )(?:\.0 )?$

See the regex demo. Details:

(?m)^ - start of a line
goodmetric - a string
.* - any zero or more chars other than line break chars, as many as possible
\h - a horizontal whitespace
(\d ) - Group 1: one or more digits
(?:\.0 )? - an optional sequence of a . and one or more 0 chars
$ - end of a line (due to (?m) modifier = Pattern.MULTILINE).

See the Java demo:

String s = "# HELP aaasd asdads\n# TYPE ASDA dasdas\ngoodmetric_total{\"camel-1\"} 777.0\n# HELP qqq www\n# TYPE eee rrr\nbadmetric_total{\"camel-1\"} 888.0";
Pattern pattern = Pattern.compile("^goodmetric.*\\h(\\d )(?:\\.0 )?$", Pattern.MULTILINE);
Matcher matcher = pattern.matcher(s);
while (matcher.find()){
    System.out.println(matcher.group(1)); 
}