Предложение

package tasks3;

import java.util.Scanner;


public class Hello1 {

    public static String join() {

        Scanner scanner = new Scanner(System.in);
        String a = scanner.nextLine();
        String delimeter = ",";
        String[] subStr = a.split(delimeter);
        subStr.toString();
        for (int i = 0; i < subStr.length; i++) {
            String head = a.substring(0, 1).toUpperCase();
            String tail = a.substring(1);
            String result = head + subStr[i];

            return result;
        }
        return null;

    }

    public static String ltrim(String s) {
        int i = 0;
        while (i < s.length() && Character.isWhitespace(s.charAt(i))) {
            i++;
        }
        return s.substring(i);
    }

    public static void main(String[] args) {
        System.out.println(join());
    }
}