import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Example {
public static void main(String[] args) {
final String regex = "(?<![\\.\\n]) ?\\n(?!\\n)";
final String string = "Below, we present an\n"
+ "introduction to advanced.\n"
+ "regular expressions, with eight commonly used concepts and examples.\n"
+ "Each example outlines a simple way to match patterns in complex strings.\n\n\n"
+ "If you do not yet have experience with basic regular expressions, have a look at this article to get started. The syntax used here matches PHP regular expressions.Regular expressions (or regex) are a powerful way to traverse large strings in order to find information. They rely on underlying patterns in a string’s structure to work their magic. Unfortunately, simple regular expressions are unable to cope with complex patterns and symbols. To deal with this dilemma, you can use advanced regular expressions.";
final String subst = " ";
final Pattern pattern = Pattern.compile(regex, Pattern.DOTALL | Pattern.MULTILINE);
final Matcher matcher = pattern.matcher(string);
// The substituted value will be contained in the result variable
final String result = matcher.replaceAll(subst);
System.out.println("Substitution result: " + result);
}
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html