Question

Please check following code.

Pattern pxPattern = Pattern.compile("^.*[0-9]+(%|pt|em).*$");
Matcher pxMatcher = pxPattern.matcher("onehellot455emwohellothree");
System.out.println(pxMatcher.matches());
System.out.println(pxMatcher.group(0));

i want to substract string 445em. i am using code for checking css. means i wants to extract

just values like 45em or 50%.

Thanks.

Answer 1

First, the captured group is in group 1, not group 0. Then you need to modify your regex to not consume the numbers and include them in the group. Try:

Pattern pxPattern = Pattern.compile("^.*?([0-9]+(?:%|pt|em)).*$");
Matcher pxMatcher = pxPattern.matcher("onehellot455emwohellothree");
System.out.println(pxMatcher.matches());
System.out.println(pxMatcher.group(1));

EDIT:

To get all values from a string with several, you can use this pattern:

Pattern pxPattern = Pattern.compile("[0-9]+(?:%|pt|em)");
Matcher pxMatcher = pxPattern.matcher("margin: 0pt, 6em, 5%, 2pt");
List<String> propertyValues = new ArrayList<String>();
while (pxMatcher.find()) {
    propertyValues.add(pxMatcher.group());
}