1 package com.citi.scala
2
3 object CollectionDemo {
4 def main(args: Array[String]): Unit =
{
5
6 /**
7 * List
8 */
9 println("--------------------------List-------------------------"
)
10 val numbers = List[Int](11, 22, 33, 44, 55
)
11 val numbers1 = List(11, 22, 33, 44, 55
)
12 val colors = List[String]("red", "green", "blue"
)
13 println(s"colors has ${colors.size}, $colors"
)
14 //取第一个
15 println(colors.head)
16 //去掉第一个，取剩下的
17 println(colors.tail)
18 //取第二个
19 println(colors(1
))
20 //遍历
21 for (s <-
colors) { println(s) }
22 //高阶函数使用
23 colors.foreach { (s: String) =>
println(s) }
24 colors.foreach { s =>
println(s) }
25 colors.foreach { println(_) }
26 val elSize = colors.map((s: String) =>
s.size)
27 println(elSize)
28 println(numbers.reduce((a: Int, b: Int) => a +
b))
29 //初始化空List
30 val ls: List[Int] =
List[Int]()
31 val lls: List[Int] =
Nil
32 println(ls ==
lls)
33 //遍历
34 var i =
numbers
35 while (!
i.isEmpty) {
36 println(i.head)
37 i =
i.tail
38 }
39
40 i =
numbers
41 while (i !=
Nil) {
42 println(i.head)
43 i =
i.tail
44 }
45 //cons操作符
46 val consNumbers = 3 :: 2 :: 1
:: Nil
47 println(consNumbers)
48
49 //List的算数运算
50 println(3 :: 2 :: 1
:: Nil)
51 println(List(7, 6, 5) ::: List(4, 3, 2, 1
))
52 println(List(4, 3, 2, 1) ++ List(7, 6, 5
))
53 println(List(1, 2) == List(2, 1
))
54 println(List(2, 1) == List(2, 1
))
55 println(List(1, 2, 3, 2, 1
).distinct)
56 println(List(1, 2, 3, 2, 1) drop (2
))
57 println(List(4, 3, 2, 1) filter { _ >= 3
})
58 println(List(List(1, 2, 3), List(4, 5, 6
)).flatten)
59
60 println((List(1, 2, 3, 4, 5).partition(_ >= 3
)))
61 println(List(1, 2, 3, 4, 5
) reverse)
62 println(List(2, 3, 5, 7, 10, 11) slice (1, 4
))
63 println(List("apple", "ben") sortBy { s =>
s.size })
64 println(List(2, 3, 5, 7, 10, 11) splitAt (3
))
65 println(List(2, 3, 5, 7, 10, 11) take (3
))
66 println(List(1, 2, 3) zip List("a", "b"
))
67 println(List(1, 2) :+ 3
)
68
69 /**
70 * Set
71 */
72 println("--------------------------Set-------------------------"
)
73 val numbersets = Set[Int](11, 22, 11, 33, 44, 55
)
74 println(s"numbersets has ${numbersets.size}, $numbersets"
)
75 println(numbersets.reduce((a: Int, b: Int) => a +
b))
76 /**
77 * Map
78 */
79 println("--------------------------Map-------------------------"
)
80 val colorMap = Map[String, Int]("red" -> 1, "green" -> 2, "yellow" -> 3
)
81 println(colorMap("red"
))
82 for (pair <-
colorMap) { println(pair) }
83
84 }
85 }
运行结果：
--------------------------List-------------------------colors has 3, List(red, green, blue)redList(green, blue)greenredgreenblueredgreenblueredgreenblueredgreenblueList(3, 5, 4)165true11223344551122334455List(3, 2, 1)List(3, 2, 1)List(7, 6, 5, 4, 3, 2, 1)List(4, 3, 2, 1, 7, 6, 5)falsetrueList(1, 2, 3)List(3, 2, 1)List(4, 3)List(1, 2, 3, 4, 5, 6)(List(3, 4, 5),List(1, 2))List(5, 4, 3, 2, 1)List(3, 5, 7)List(ben, apple)(List(2, 3, 5),List(7, 10, 11))List(2, 3, 5)List((1,a), (2,b))List(1, 2, 3)--------------------------Set-------------------------numbersets has 5, Set(33, 22, 44, 11, 55)165--------------------------Map-------------------------1(red,1)(green,2)(yellow,3)
转载于:https://www.cnblogs.com/AK47Sonic/p/7073855.html
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