Java : A string consists of parenthesis and letters. Write a program to validate all the parenthesis.

import java.util.*;
/*
 *
 *  A string consists of parenthesis and letters. Write a program to validate all the parenthesis.
 *  Ignore the letters.eg.
 *  ((alf)ls) – valid
 *  )(dkk)() – invalid
 */

public class StringI_1 {

 public static void main(String[] args) {

  Scanner sc = new Scanner(System.in);
  System.out.print("Enter string :-  ");
  String str = sc.nextLine();
  
  System.out.println("Entered string is :-  " + str);
  
  int countOpen = 0 ;
  int countClose =0 ;
  int sizeOfString = str.length();

if(str == null || sizeOfString == 0){
            System.out.println("String is Empty");
            System.exit(0);
            } 
  
  if (str.charAt(0) != '(' && str.charAt(sizeOfString - 1) != ')' ){
   System.out.println("First : Invalid String");
   System.exit(0);
   
  }
  /*else
   System.out.println("valid");*/
  
  for(int i = 0 ; i< sizeOfString ; i++){
   
    if(str.charAt(i) == '(' && i!=(sizeOfString-1) ){
      if( str.charAt(i+1) == ')' ){
       System.out.println("Second :Invalid String ");
      System.exit(0);
      }else{
      countOpen++;
      System.out.println("countOpen :- " + countOpen +" "+ str.charAt(i));
      }
    }else {
       if(str.charAt(i) == ')' ){   //&& str.charAt(i+1) !=')'
       countClose++;
       System.out.println("countClose :- " + countClose +" "+ str.charAt(i));
      }
  } 
  }   
  if(countOpen == countClose){
   System.out.println("Valid string");
  }else{
    System.out.println("Third : Invalid String");
   }
  }
  
 }