Date validation with Java

This is a date validation with. It will validate the date forma(yyyy-MM-dd), valid month date/month and leap year.

private static String RUN_DATE_REGEX = "((20)\\d\\d)-(0?[1-9]|1[012])-(0?[1-9]|[12][0-9]|3[01])";

private static Pattern datePattern = Pattern.compile(RUN_DATE_REGEX);

private static Matcher dateMatcher;

public static boolean isDateValid(final String dateString){

dateMatcher = datePattern.matcher(dateString);

if(dateMatcher.matches()){

   dateMatcher.reset();

   if(dateMatcher.find()){

String[] dateArr = dateString.split("-");

int year = Integer.parseInt(dateArr[0]);

int month = Integer.parseInt(dateArr[1]);

int day = Integer.parseInt(dateArr[2]);

if((day ==31) && (month == 4 || month == 6|| month == 9 || month == 11)){

   return false; // 1,3,5,7,8,10,12 has 31 days

}else if(month == 2){

   

   if((day == 30) || (day == 31)){

return false;

   }

   

   if((year % 4) != 0){

if(day == 29){

   return false;

}

   }

   return true;

}else{

   return true;

}

   }

}

return false;

    }