HackerRank-Solutions/Java/Strings/Pattern Syntax Checker/Solution.java

import java.util.Scanner;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

/* If a PatternSyntaxException is not thrown by Pattern.compile,
   then the regular expression is valid.
*/
public class Solution {
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int testCases = Integer.parseInt(scan.nextLine());
        while (testCases-- > 0){
           String pattern = scan.nextLine();
           try {
               Pattern.compile(pattern);
               System.out.println("Valid");
           } catch (PatternSyntaxException exception) {
               System.out.println("Invalid");
           }
        }
        scan.close();
    }
}