Scala基本语法

windows版本

C:\Program Files\scala\bin>scala -version
Scala code runner version 2.10.3 -- Copyright 2002-2013, LAMP/EPFL

基本类型及操作

import scala.collection.mutable.Set
import scala.collection.immutable.HashSet
import scala.collection.mutable.Map

object Hello {
	//函数
	def max(x: Int, y: Int): Int = {
		if(x > y) x
		else y
	}

	//循环:while / for / foreach三种方式
	def loop(args: Array[String]) { 
        var i = 0  
        while(i < args.length) {  
                println(args(i))  
                i = i + 1  
        }  
  /*
        for(i <- 0 until args.length) {  
                println(args(i))  
        }
  
        args.foreach { arg =>  
                println(arg)  
        }
	*/}

	//数组
	def useArray(){
		val greetStrings = new Array[String](3)//不推荐这种创建数组方法
		greetStrings(0) = "Hello"
		greetStrings(1) = ", "
		greetStrings(2) = "world!\n"

		greetStrings.update(0, "Hi")//同上
		greetStrings.update(1, ", ")
		greetStrings.update(2, "world!\n")

		greetStrings(0) = "Hey"

		for (i <- 0 to 2)
			print(greetStrings(i))

		val betterStrings = Array("Hello",", ","World\n")//推荐此类用法
	}

	//列
	def useList(){
		val oneTwo = List(1, 2)
		val twoThree = List(2, 3)
		val oneTwoThree = 1 :: twoThree //拼接元素和数组
		val oneTwoThreeFour = oneTwo ::: twoThree //拼接数组和数组

		val thrill = "Will" :: "fill" :: "until" :: Nil
		println(thrill) // List(Will, fill, until)

		thrill.drop(2)  //Until
		thrill(2) //Until
		thrill.dropRight(2) //Will
		thrill.count(s => s.length == 4) // return 2
		thrill.exists(s => s == "until") // true
		thrill.filter(s => s.length == 4) // List("Will", "fill")
		//thrill.remove(s => s.length == 4) // List("until")
		thrill.forall(s => s.endsWith("l")) // true (all endwith l)
		thrill.head // Will
		thrill.init // return all without last List("Will", "fill")
		thrill.tail // return all without first List("fill", "until")
		thrill.length // 3
		thrill.last // until
		thrill.isEmpty // false
		thrill.map(s => s + "y") // List("Willy", "filly", "untily")
		thrill.mkString(", ") // "Will, fill, until"
		thrill.reverse // List("until", "fill", "Will")
		//thrill.sort((s, t) => s.charAt(0).toLowerCase < t.charAt(0).toLowerCase) // List("fill", "until", "Will") 编译有错


	}

	//关联数组
	def useOther(){
		//tuple 可以存放不同类型
		val pair = (99, "Luftballons")
		println(pair._1)
		println(pair._2)

		//sets
		val movieSet = Set("Hitch", "Poltergeist")
		movieSet += "Shrek"
		println(movieSet)

		//hashset
		val hashSet = HashSet("Tomatoes", "Chilies")
		println(hashSet + "Coriander")

		//map
		val treasureMap = Map[Int, String]()
		treasureMap += (1 -> "Go to island.")
		treasureMap += (2 -> "Find big X on ground.")
		treasureMap += (3 -> "Dig.")
		println(treasureMap(2))
	}

	def main(args: Array[String]): Unit = {
		//变量|常量
		var msg1 = "message one" //scala自动匹配类型
		var msg2 : java.lang.String = "message two" //scala指定类型
		var msg3 : String = "message three" //可以直接引用java.lang包
		msg1 = "message one changed"
		val c_msg1 = "constant message one"
		//c_msg1 = "constant message one cann't be changed"

		//使用java类
		val big = new java.math.BigInteger("12345")

		loop(args)
		println(max(3,4))

		useArray()
		useList()
		useOther()
	}
}

 类，单例（需要编译运行scalac scala）

class Tool {
	def max(x: Int, y: Int): Int = {
		if(x > y) x
		else y
	}
}

object Tool2{
	def min(x: Int, y: Int): Int = {
		if(x < y) x
		else y
	}
}

object Hello {
	//函数
	def main(args: Array[String]): Unit = {
		println("hello")

		val t = new Tool()
		println(t.max(3,4))
		println(Tool2.min(3,4))
	}
}