Java 8中怎么创建 Stream

Java 8中怎么创建 Stream ，很多新手对此不是很清楚，为了帮助大家解决这个难题，下面小编将为大家详细讲解，有这方面需求的人可以来学习下，希望你能有所收获。

1、Stream.of 可变参数

Stream stream1 = Stream.of("A", "B", "C");System.out.println("stream1:" + stream1.collect(joining()));

程序输出：

stream1:ABC

2、Stream.of 数组

String[] values = new String[]{"A", "B", "C"};Stream stream2 = Stream.of(values);System.out.println("stream2:" + stream2.collect(joining()));

程序输出：

stream2:ABC

看 Stream.of 源码，上面这两种方式其实就是第三种方式的包装版。

public static Stream of(T... values) {    return Arrays.stream(values);}

我们直接使用源码中的方式也是一样的。

3、Arrays.stream

String[] values = new String[]{"A", "B", "C"};Stream stream3 = Arrays.stream(values);System.out.println("stream3:" + stream3.collect(joining()));

程序输出：

stream3:ABC

4、List

List list = Arrays.asList("A", "B", "C");Stream stream4 = list.stream();System.out.println("stream4:" + stream4.collect(joining()));

程序输出：

stream4:ABC

5、Set

Set set = new HashSet<>(Arrays.asList("A", "B", "C"));Stream stream5 = set.stream();System.out.println("stream5:" + stream5.collect(joining()));

程序输出：

stream5:ABC

6、Map

Map map = new HashMap<>();map.put("1", "A");map.put("2", "B");map.put("3", "C");Stream stream6 = map.values().stream();System.out.println("stream6:" + stream6.collect(joining()));

程序输出：

stream6:ABC

7、Stream.iterate

Stream stream7 = Stream.iterate("A", e -> String.valueOf((char) (e.charAt(0) + 1))).limit(3);System.out.println("stream7:" + stream7.collect(joining()));

程序输出：

stream7:ABC

8、Pattern

String value = "A B C";Stream stream8 = Pattern.compile("\\W").splitAsStream(value);System.out.println("stream8:" + stream8.collect(joining()));

程序输出：

stream8:ABC

9、Files.lines

try {    Stream stream9 = Files.lines(Paths.get("d:/data.txt"));    System.out.println("stream9:" + stream9.collect(joining()));} catch (IOException e) {    e.printStackTrace();}

data.txt文件内容如下：

ABC

程序输出：

stream9:ABC

10、Stream.generate

Stream stream10 = Stream.generate(() -> "A").limit(3);System.out.println("stream10:" + stream10.collect(joining()));

程序输出：

stream10:AAA

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