创建Stream

1.创建Stream　　　　　　　　

create Stream from Collections;

create Stream from values;

create Stream from Arrays;

craeate Stream from files;

craeate Stream from functions

代码举例：

 1 package com.cy.java8;
 2 
 3 import java.io.IOException;
 4 import java.nio.file.Files;
 5 import java.nio.file.Path;
 6 import java.nio.file.Paths;
 7 import java.util.Arrays;
 8 import java.util.List;
 9 import java.util.stream.Stream;
10 
11 public class CreateStream {
12 
13     public static void main(String[] args) {
14         createStreamFromCollection().forEach(System.out::println);
15 
16         createStreamFromValues().forEach(System.out::println);
17 
18         createStreamFromArrays().forEach(System.out::println);
19 
20         createStreamFromFile().forEach(System.out::println);
21     }
22 
23 
24     /**
25      * create stream from collection
26      * 这里list的元素的顺序放到strem中不会改变，原来是什么样的顺序，stream中就是什么样。
27      * @return
28      */
29     private static Stream<String> createStreamFromCollection(){
30         List<String> list = Arrays.asList("hello", "world", "stream");
31         return list.stream();
32     }
33 
34     private static Stream<String> createStreamFromValues(){
35         return Stream.of("hello", "world", "stream");
36     }
37 
38     private static Stream<String> createStreamFromArrays(){
39         String[] strings = new String[]{"hello", "world", "stream"};
40         return Arrays.stream(strings);
41     }
42 
43     /**
44      * create stream from file
45      * @return
46      */
47     private static Stream<String> createStreamFromFile(){
48         Path path = Paths.get("F:\\IdeaProjects\\Java8Learning\\java8\\src\\main\\java\\com\\cy\\java8\\CreateStream.java");
49         Stream<String> lines = null;
50         try {
51             lines = Files.lines(path);
52         } catch (IOException e) {
53             throw new RuntimeException(e);
54         }
55         return lines;
56     }
57 }

打印结果如下：

hello
world
stream
hello
world
stream
hello
world
stream
package com.cy.java8;

import java.io.IOException;
....
把CreateStream.java文件分行打印出来了...

　　

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