Scala集合类实用操作集合

1. 与java对象互相转化

   // java list to scala array
   import scala.collection.JavaConversions._ 
   
   // scala array to java list 
   import collection.JavaConversions._ 

2. seq转化为参数序列(:_*)

object x {

  def test(args: Int*) = {
    println(args.sum)
  }

  def main(args: Array[String]): Unit = {
    val a = Array(1, 2, 3)
    test(a: _*)
  }

}

结果: 6

3. to string

val a = Array(1,2,3)
println(a.mkString("_"))

ouptu: 1_2_3

4. 创建空值对象

val a = Array.empty[String]