scala中常用特殊符号详解

public int function(int x) {
 return x+1;
}

class Symbol {
 var add = (x: Int) => x + 1
}

object test2 {
 def main (args: Array[String] ): Unit = {
 var symbol = new Symbol
 printf(""+ symbol.add.toString())
 }
}

var list = Array(1,2,3,4)
for (aa <- list) {
 printf(aa+" ")
}

int[] list = {1,2,3,4};
for(int aa : list) {
 System.out.print(aa+" ");
}

var s:String = "a"
s+="b"
println(s)
s++="c"
println(s)

val one = List(1,2,3)
val two = List(4,5,6)
val three = one ::: two
println(three.toString())

val four = 7 :: three

println(four.toString())

val first = (1,2,3) // 定义三元元组

val one = 1
val two = 2
val three = one -> two

println(three) // 构造二元元组

println(three._2) // 访问二元元组中第二个值

import org.apache.spark.SparkContext._

val lst = List(1,2,3,4,5)
val lstFilter = lst.filter(_ > 3)

val ss = (1,"22","333")
println(ss._1)

val m = Map(1 -> 2,2 -> 4)
for ((k,_) <- m) println(k) //如果不需要所有部件， 则在不需要的部件使用_； 本例只取key,因此在value处用_

var s:Int=_
def main(args: Array[String]): Unit = {
 println(s)
}

def main(args: Array[String]): Unit = {
 val s = sum(1 to 5:_*)  //把1 to 5当作一个序列处理
 println(s)
}

def sum(args: Int*) : Int = {
 var result = 0 ;
 for(s2 <- args) {
  result += s2 ;
 }
 result ;
}

val arrBuf1 = new ArrayBuffer[Int]()
arrBuf1+= 11 // 添加一个元素

println(arrBuf1)

val arrBuf1 = new ArrayBuffer[Int]()
arrBuf1+= 11 // 添加一个元素
arrBuf1+= 12 // 添加一个元素
arrBuf1-= 12 // 删除一个元素

println(arrBuf1)

var map = Map(1 -> 1,2 -> 2,3 ->3 )
map-=1
println(map)