Syntax_Checker.java

import java.util.Scanner;
import java.util.regex.*;

public class Solution
{
	public static void main(String[] args){
		Scanner in = new Scanner(System.in);
		int testCases = Integer.parseInt(in.nextLine());
		while(testCases>0){
			String pattern = in.nextLine(); //enter the string..
 	//Write your code
 try
 {
 Pattern.compile(pattern); //this method will take the input and check the regex is valid or not..if it gives an exception then it is not valid..
 System.out.println("Valid"); 
 }
 catch (PatternSyntaxException p) //suppose the regex is not valid then the exception generated will be (PatternSyntaxException)...
 {
 System.out.println("Invalid"); //print invalid..
 }
 testCases--; //decreasing the value..
		} 
	}
}