向java程序中添加函数

我正在写我的第一个java程序，我终于把它全部写出来了，但是在作业中我需要添加一个函数而不是main。我的程序计算名字中字母的数量，所以我想也许我可以添加一个函数来读取大写字母的数量？有什么想法吗

public class NameLetters{

    public static void main(String []args){  

        Scanner in = new Scanner(System.in);

        String firstName;   //Asks for the users first name

        int count=0;        //Count the letters passing through loop

        System.out.print("Hello, this program will ask for your first name and then output the number of letters in your name.");

        System.out.print("Please enter your first name:");

        String firstName = input.NextLine();

        for (int i=0; i<firstName.length(); i++) {
            if (firstName.charAt(i) != ' ')
                Count ++;
        } 

        system.out.print("There are "+Count+" s in the first name "+firstName+" , Thank you for participating. Goodbye!"); 
    }
}

---

是的，请阅读教程，例如使用。这不是单独的函数，它只适用于我们的ascii字符串

            String s = "NaMe";
            int upper = 0;
            int lower = 0;
            for(int i = 0; i<s.length();i++ ) {
                int charASCII= (int)s.charAt(i);
                if (charASCII <91 && charASCII > 64){
                    upper ++;
                }
                if (charASCII <123 && charASCII > 96){
                    lower ++;
                }
            }
            System.out.print("Given name string contains "+upper+ " uppercase letters & "+lower + " lowercase letters");