Java Regular Expression

public static String joinList(List<Integer> list, String literal) {
    return list.toString().replaceAll(",", literal).replaceAll("[\[.\].\s+]", "");
}

public static String randomNumber(){
      Long randomNumber =  (long) Math.floor(Math.random() * 9000000000L) + 1000000000L;
      String number = Long.toString(randomNumber);
      return number;
}

public static String currentDate(String dateFormat){
      SimpleDateFormat s = new SimpleDateFormat(dateFormat);  
      Calendar cal = Calendar.getInstance();  
      return s.format(new Date(cal.getTimeInMillis()));
}
 

public static boolean isNumeric(String inputString) {
      return inputString.matches("[-+]?\d*\.?\d+");
}

public static boolean isAlphabetic(String inputString) {
      return inputString.matches("[a-zA-Z]+");
}

public static boolean isEmailFormat(String inputString) {
      return inputString.matches("^[\w!#$%&'*+/=?`{|}~^-]+(?:\.[\w!#$%&'*+/=?`{|}~^-]+)*@(?:[a-zA-Z0-9-]+\.)+[a-zA-Z]{2,6}$");
}

public static boolean isAlphaNumeric(String inputString) {
      return inputString.matches("^[a-zA-Z0-9\s]*$");
}