2.创建流的四种方式

一、.stream() ，调用stream()方法直接返回流

List<Person> personList = new Person();
Stream<Person> stream = personList.stream();//返回顺序流
Stream<Person> parallelStream = psersonList.parallelStream();//返回一个并行流

二、Arrays.stream()

int[] arr = new int[]{1, 2, 3, 4};
IntStream stream = Arrays.stream(arr);

三、stream.of()

//泛型为传入的对象
Stream<String> stream1 = Stream.of("1", "2");
Stream<Integer> stream2 = Stream.of(1, 2);

四、无限流（没太理解）

Stream<Integer> stream3 = Stream.iterate(0, t -> t + 5);