validate a user input

Hello I'm new to programming and I'm having a trouble understanding my assignment. I know that this might be a really simple problem for you guys and I'm sorry for that. Is it possible that she's just asking me to write a method that will perform the given instructions?

Write a program to find if the user input is valid base on the instructions.**

1. a string must have at least nine characters
2. a string consists of letters and numbers only.
3. a string must contain at least two digits.

Requirement #1: a string must have at least nine characters

This is solved by checking whether the length of the String is greater than 9, with s.length()>9

Requirement #2: a string consists of letters and numbers (whole numbers) only.

Use the regex [a-zA-Z0-9]+, which matches all Latin alphabet characters and numbers.

Requirement #3: a string must contain at least two digits.

I've written a method that loops through every character and uses Character.isDigit() to check whether it is a digit.

Check it out:

public static boolean verify(String s) {
    final String regex = "[a-zA-Z0-9]+";
    System.out.println(numOfDigits(s));
    return s.length() > 9 && s.matches(regex) && numOfDigits(s) > 2;
}

public static int numOfDigits(String s) {
    int a = 0;
    int b = s.length();
    for (int i = 0; i < b; i++) {
        a += (Character.isDigit(s.charAt(i)) ? 1 : 0);
    }
    return a;
}