Repository navigation
Expand file tree
/
Copy pathBuildingStreams.java
More file actions
93 lines (76 loc) · 2.83 KB
/
Copy pathBuildingStreams.java
File metadata and controls
93 lines (76 loc) · 2.83 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
package com.brianway.learning.java8.streamapi;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.function.IntSupplier;
import java.util.stream.IntStream;
import java.util.stream.Stream;
/**
* 构建流:从值序列,数组,文件来创建流
* 斐波拉切数列的几种生成方法
*/
public class BuildingStreams {
public static void main(String... args) throws Exception {
/**
* 由值创建流
*/
// Stream.of
Stream<String> stream = Stream.of("Java 8", "Lambdas", "In", "Action");
stream.map(String::toUpperCase).forEach(System.out::println);
// Stream.empty
Stream<String> emptyStream = Stream.empty();
/**
* 由数组创建流
*/
// Arrays.stream
int[] numbers = {2, 3, 5, 7, 11, 13};
System.out.println(Arrays.stream(numbers).sum());
/**
* 由函数生成流：创建无限流
*/
// Stream.iterate
Stream.iterate(0, n -> n + 2)
.limit(10)
.forEach(System.out::println);
// fibonnaci with iterate
Stream.iterate(new int[] {0, 1}, t -> new int[] {t[1], t[0] + t[1]})
.limit(10)
.forEach(t -> System.out.println("(" + t[0] + ", " + t[1] + ")"));
Stream.iterate(new int[] {0, 1}, t -> new int[] {t[1], t[0] + t[1]})
.limit(10)
.map(t -> t[0])
.forEach(System.out::println);
// random stream of doubles with Stream.generate
Stream.generate(Math::random)
.limit(10)
.forEach(System.out::println);
// stream of 1s with Stream.generate
IntStream.generate(() -> 1)
.limit(5)
.forEach(System.out::println);
IntStream.generate(() -> 2)
.limit(5)
.forEach(System.out::println);
IntSupplier fib = new IntSupplier() {
private int previous = 0;
private int current = 1;
public int getAsInt() {
int nextValue = this.previous + this.current;
this.previous = this.current;
this.current = nextValue;
return this.previous;
}
};
IntStream.generate(fib).limit(10).forEach(System.out::println);
/**
* 由文件生成流
*/
String path = BuildingStreams.class.getResource("/").getPath() + "/data-building.txt";
long uniqueWords = Files.lines(Paths.get(path), Charset.defaultCharset())
.flatMap(line -> Arrays.stream(line.split(" ")))
.distinct()
.count();
System.out.println("There are " + uniqueWords + " unique words in data.txt");
}
}