流的扁平化flatMap

package com.ant.jdk8.chap05;

import java.util.Arrays;
import java.util.List;

public class StreamMapDemo {
    public static void main(String[] args) {
        List<String> words = Arrays.asList("Hello","World");
        words.stream()
                .map(word->word.split(""))
                .flatMap(Arrays::stream)
                .distinct().forEach(System.out::print);
    }
}