public static void main(String[] args) {

// 1.对流中每一个元素应用函数

List<String> dishes = Dish.menu.stream()

.map(Dish::getName)

.collect(Collectors.toList());

// [pork, beef, chicken, french fries, rice, season fruit, pizza, prawns, salmon]

System.out.println(dishes);

// 2.返回集合中每个元素的长度

List<String> words = Arrays.asList("Java 8", "Lambdas", "In", "Action");

List<Integer> wordLengths = words.stream().map(String::length).collect(Collectors.toList());

// [6, 7, 2, 6]

System.out.println(wordLengths);

// 3.返回列表中的单词中互不相同的字符的集合

String[] words2 = {"Hello", "World"};

List<String> uniqueCharacters = Arrays.stream(words2)

.map(word -> word.split(""))

.flatMap(Arrays::stream)

.distinct()

.collect(Collectors.toList());

// [H, e, l, o, W, r, d]

System.out.println(uniqueCharacters);

// 4.输出输入的每个数的平方构成的列表

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);

List<Integer> numberResult = numbers.stream().map(n -> n * n).collect(Collectors.toList());

// [1, 4, 9, 16, 25]

System.out.println(numberResult);

// 5.给定两个数字列表，返回所有的数对

List<Integer> a1 = Arrays.asList(1, 2, 3);

List<Integer> a2 = Arrays.asList(4, 5);

List<int[]> r = a1.stream()

.flatMap(i -> a2.stream()

.map(j -> new int[]{i, j}))

.collect(Collectors.toList());

r.forEach(t -> {

// [1, 4][1, 5][2, 4][2, 5][3, 4][3, 5]

System.out.print("[" + t[0] + ", " + t[1] + "]");

});

System.out.println();

// 6.给定两个数字列表，返回所有只被3整除的数对

List<int[]> r2 = a1.stream()

.flatMap(i -> a2.stream()

.filter(j -> (i + j) % 3 == 0)

.map(j -> new int[]{i, j}))

.collect(Collectors.toList());

r2.forEach(t -> {

// [1, 5][2, 4]

System.out.print("[" + t[0] + ", " + t[1] + "]");

});

System.out.println();

}