public static void main(String[] args) {
        int count = 0;
        int currentComprimation = -1;
        String s ="aabbbccccc";

        for (int i =  0; i < s.length(); i++) {
            if(currentComprimation == s.charAt(i)) {
                count++;
            } else {
                if(currentComprimation != -1) {
                    System.out.print((char) currentComprimation + "" + count);
                }
                count = 1;
                currentComprimation = s.charAt(i);
            }
        }
        System.out.print((char)currentComprimation + "" + count);
    }