Turn String aaaabbbbffffd into a4b4d3

Question

I\'m trying to get a head start on practicing interview questions and I came across this one:

Turn String aaaabbbbffffd into a4b4d3

You would basically want t

Answer 1

To add on to @Makoto's wonderful answer, in your situation, I would use a TreeMap instead of a HashMap. A TreeMap will allow you to print in alphabetical order. I have also added the print code to show you how it would look. It's fully runnable.

import java.util.Map;
import java.util.TreeMap;

public class MapPractice {

    public static void main(String[] args) {
        Map map = new TreeMap<>();

        String blah = "aaaabbbbffffd";

        for (int i = 0; i < blah.length(); i++) {
            char c = blah.charAt(i);
            if (!map.containsKey(c)) {
                map.put(c, 1);
            } else {
                map.put(c, (map.get(c) + 1));
            }
        } 

        for (Map.Entry entry: map.entrySet()) {
            System.out.print(entry.getKey() + "" + entry.getValue());
        }
    }
}

Output with TreeMap: a4b4d3

Output with HashMap: d3b4a4