Understand difference between map and flatmap

MapAndFlapMapUnderstanding.java

package com.java8.streams;

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class MapAndFlapMapUnderstanding {

    public static void main(String[] args) {

        System.out.println("Map example : \nTake string list  and return list of integers having size of strings respectively");
        List<String> listOfString = Arrays.asList("Str1", "String22", "RandomString", "AanotherRandomString");
        List<Integer> charactersInStringList = listOfString.stream().map(string -> string.length()).collect(Collectors.toList());
        charactersInStringList.forEach(element -> System.out.print(element + " "));

        System.out.println("\nFlatMap : convert list of list of integers into single list of integers");
        List<List<Integer>> listOfListOfIntegers = Arrays.asList(Arrays.asList(1, 2), Arrays.asList(3, 4), Arrays.asList(5, 6));
        System.out.println("list of list of integers before flattening" + listOfListOfIntegers);

        List<Integer> listInteger = listOfListOfIntegers.stream().flatMap(list -> list.stream()).collect(Collectors.toList());
        System.out.println("list of list of integers after flattening" + listInteger);

    }
}

Output : 
Map example : 
take string list  and return list of integers having size of strings respectively
4 8 12 20 
FlatMap : convert list of list of integers into single list of integers
list of list of integers before flattening[[1, 2], [3, 4], [5, 6]]
list of list of integers after flattening[1, 2, 3, 4, 5, 6]