How to check if a given Regex is valid?

Question

I have a little program allowing users to type-in some regular expressions. afterwards I like to check if this input is a valid regex or not.

I'm wondering if there is a build-in method in Java, but could not find such jet.

Can you give me some advice?

Answer 1

Here is an example.

import java.util.regex.Pattern; import java.util.regex.PatternSyntaxException;  public class RegexTester {     public static void main(String[] arguments) {         String userInputPattern = arguments[0];         try {             Pattern.compile(userInputPattern);         } catch (PatternSyntaxException exception) {             System.err.println(exception.getDescription());             System.exit(1);         }         System.out.println("Syntax is ok.");     } } 

java RegexTester "(capture" then outputs "Unclosed group", for example.