Stream - Map

原创转载请注明出处：http://agilestyle.iteye.com/blog/2425203

 

map

private static void mapTest() {
    List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6, 7);

    List<Integer> result = list.stream().map(i -> i * 2).collect(Collectors.toList());

    System.out.println(result);
}

Console Output

[2, 4, 6, 8, 10, 12, 14]

  

flatMap

private static void flatMapTest() {
    String[] words = {"Hello", "World"};

//        Stream<String> stream = Arrays.stream(words);
//        Stream<String[]> stream1 = stream.map(w -> w.split(""));
//        Stream<String> stringStream = stream1.flatMap(Arrays::stream);
//        stringStream.distinct().forEach(System.out::println);

    Arrays.stream(words).map(w -> w.split("")).flatMap(Arrays::stream).distinct().forEach(System.out::print);
}

Console Output

HeloWrd

Using flatMap to find the unique characters from a list of words  

 

Reference

Manning.Java.8.in.Action.Lambdas.Streams.and.functional-style.programming