Scala元组 *可以包含不同类型的元素 *最多支持22个元素 *使用下划线“_”访问元素，“_1”表示第一个元素 //元组声明方式一 var tp1=(“Mike”,“123 ABC”,58) println(tp1._1) println(tp1._2) printlin(tp1._3) //迭代元组 tp1.productIterator.foreach{i=>println(“Value=”+i)}
//元组声明方式二 var tp2=new Tuple3(“Mike”,“123 ABC”,58)
//元组声明方式三 “xjia”- >4 //(String Int)=(xia,4)
//将元组元素依次赋给三个变量 val(name,address,age)=tp1 println(name) println(address) parintln(age)
Scala集合-分类 *Seq 序列，元素按顺序排列 *Set 集合，元素不重复 *Map 映射，键值对集合
常用集合 名称 可变/不可变 示例 ArrayBuffer mutable val buffer = scala.collection.mutable.ArrayBuffer[Int](10, 20, 30); buffer+=(2,3) Array mutable val arr=Array(1,2,3) List immutable val lst=List(1,2,3) Map mutable val stu= Map(“name” -> “Jason”, “age” -> “18”) Set mutable/immutable val set=Set(1,2,3) Vector immutable val v=Vector(1, 3, 5, 7, 11, 13) Stack mutable/immutable val st=scala.collection.mutable.Stack(1,2,3) //堆栈，先进后出 Queue mutable/immutable val q=scala.collection.mutable.Queue(1,2,3) //队列，先进先出 BitSet mutable/immutable val bit=scala.collection.mutable.BitSet(3,2,0) //位集合 ListMap immutable val map = scala.collection.immutable.ListMap(1->“one”, 2->“two”) HashSet mutable val set= scala.collection.mutable.HashSet(1,2,3) HashMap mutable val stu= scala.collection.mutable.HashMap(“name” -> “Jason”, “age” -> “18”)
①Scala List常用操作
var c=List(‘a’,‘b’,‘c’) var x=‘x’+:c //List[char]=List(x,a,b,c) var c = List[Char](‘a’, ‘b’, ‘c’) var x = ‘x’ +: c // (x, a, b, c) var y = c :+ ‘x’ // (a, b, c, x) import scala.collection.mutable._ va lb = ListBuffer[Int](1, 2, 3, 4) lb += 100 //1, 2, 3, 4, 100 lb += (21, 33)// 88 +=: lb //88, 1, 2, 3, 4, 100, 21, 33 List(77, 66) ++=: lb
var l = List[Int](2, 3, 4, 6, 8, 9, 11, 20) var x = l grouped 3 //等价l.grouped(3) x.next() //(2, 3, 4) x.next() //(6, 8, 9) var y = l sliding 2 y.next() // (2, 3) y.next() // (3, 4)
var a1 = Array[Int](1, 2, 3, 4) var a2 = Array[Int](100, 200, 300, 400) var a = List.concat(a1, a2)//Array->List a3=a1++a2 //Arrays->Array a(3) = 333 //Error a3(3)=333 //OK var b = Array(333, “333”, ‘3’, false ) var c = List.concat(a, b) val x = a.filter( _ %2 != 0 ) val y = a.reverse var m = a.groupBy(t => t%2 == 0) var n = a.slice(2, 4) a.sorted //1, 2, 3, 4, 100, 200, 300, 400 a.sorted( Ordering.Int.reverse ) a.sortWith( _ > _ ) a.sortBy( x => x ) //升序 a.sortBy( x => x*(-1) ) //降序
②Scala Set常用操作
var s = Set(“ab”, “yz”) s += “mn” //mn, ab, yz s += “mn” //?? s -= “yz” //mn, ab var t = Set(“ab”, “gh”, “mn”, “st”, “yz” ) t – s //gh, st, yz t ++ s //ab, gh, mn, st, ya
var os = SortedSet(1, 99, 66, 54, 77 ) os //1, 54, 66, 77, 99 os += 33 os //1, 33, 54, 66, 7
var s = Set(“ab”, “yz”) var t = Set(“ab”, “gh”, “mn”, “st”, “yz” ) //求交集 t & s t intersect s //求并集 t | s t union s //求差集 t &~ s t diff s
import scala.collection.mutable SortedSet(10,2,4,8,9) // scala.collection.mutable.SortedSet[Int]=TreeSet(2,4,8,9,10)
③Scala Map常用操作 var m = Map[String, Int](“a”->1, “b”->2, “c”->3, “d”->4, “e”->5, “f”->6, “g”->7, “h”->8, “i”->9) m(“a”) //1 m += (“j”->0) m += (“j”->0) //?? m += (“j”->11) //?? var n = m ++ Map[String, Int](“a”->3, “j”->99) //?? n -= (“g”, “e”)
遍历map for((k,v)<-m)(println(k+v)) //有序Map，按照key的字母序进行排序 val m2=scala.collection.SortedMap(“dd”->25,“c”->30,“aa”->25,“bb”->29) //定义一个可变map val sti=scala.collectiom.mutable.Map(“jack”->20,“tom”->21,“peter”->22)
