String Frequency Counter

import java.util.HashMap;

public class CharFrequency {
    public static void main(String[] args) {
        String str = "programming";
        HashMap<Character, Integer> freq = new HashMap<>();
        for (char c : str.toCharArray())
            freq.put(c, freq.getOrDefault(c, 0) + 1);
        freq.forEach((k, v) -> System.out.println(k + ": " + v));
    }
}