Java Regex for matching quoted string with escaped quotes

Question

I know there are already many questions like mine but I found no answer which works in Java. So I write a new question.

I have text files with content like this:

key1 = "This is a \"test\" text with escapes using '\\' characters";
key2 = 'It must work with \'single\' quotes and "double" quotes';

I need a regular expression which matches the values in the double-quotes (or single-quotes). This regular expression must support the escaped quotes and escaped backslashes. The regular expression must work with Java standard Pattern/Matcher classes.

Answer 1

Try this regular expression:

'([^\\']+|\\([btnfr"'\\]|[0-3]?[0-7]{1,2}|u[0-9a-fA-F]{4}))*'|"([^\\"]+|\\([btnfr"'\\]|[0-3]?[0-7]{1,2}|u[0-9a-fA-F]{4}))*"

And as a string literal:

"'([^\\\\']+|\\\\([btnfr\"'\\\\]|[0-3]?[0-7]{1,2}|u[0-9a-fA-F]{4}))*'|\"([^\\\\\"]+|\\\\([btnfr\"'\\\\]|[0-3]?[0-7]{1,2}|u[0-9a-fA-F]{4}))*\""