import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collectors;

public class CharacterCount {
    public static void main(String[] args) {
        String input = "hello world";
        Map<Character, Long> charCount = input.chars()
                .mapToObj(c -> (char) c)
                .collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));

        System.out.println(charCount);
    }
}