1 陣列

1.1 定長陣列

• 類名（） ==》 呼叫 Object 的apply方法
  
  

1.2 可變陣列

package com.scalatest.scala.array

//繼承了 App ，不用寫main方法了
object ArrayApp  extends App{

    val b = scala.collection.mutable.ArrayBuffer[Int]()
    b += 1
    b += 2
    println(b)

}

package com.scalatest.scala.array

//
 
繼承了 App ，不用寫main方法了
object ArrayApp extends App {

    val b = scala.collection.mutable.ArrayBuffer[Int]()
    b += 1
    b += 2
    b += (3, 4, 5, 6)
    b ++= Array(8, 9, 10) // ArrayBuffer(1, 2, 3, 4, 5, 6, 8, 9, 10)

    b.insert(0, 0) // ArrayBuffer(0, 1, 2, 3, 4, 5, 6, 8, 9, 10)

    b.remove(1) // ArrayBuffer(
 
0, 2, 3, 4, 5, 6, 8, 9, 10)
    b.remove(0, 3) // ArrayBuffer(4, 5, 6, 8, 9, 10)

    b.trimEnd(2) // ArrayBuffer(4, 5, 6, 8)

    for (i <- 0 until b.length) {
        print(b(i))
    }
    println()

    for (i <- (0 until b.length).reverse) {
        print(b(i))
    }

    println()
    for (ele <
 
- b) {
        print(ele)
    }

    println()
    println(b)

}

2 List

package com.scalatest.scala.array

object ListApp extends App{
    val l = List(1,2,3,4,5)

    val l5 = scala.collection.mutable.ListBuffer[Int]()
    l5 += 2
    l5 += (3,4,5)
    l5 ++= List(6,7,8) // ListBuffer(2, 3, 4, 5, 6, 7, 8)

    l5 -= 2 // ListBuffer(3, 4, 5, 6, 7, 8)

    l5 -= (3,100) // ListBuffer(4, 5, 6, 7, 8)

    l5 --= List(5,6,7,8) // ListBuffer(4)
    

    println(l5)

}

2.1 Nil 一個空的不可變集合

2.2 List 的 head tail

• 第一個是 head,其餘的都是 tail
  

• :: 分隔 head,tail
  

2.3 :_*

package com.scalatest.scala.array

object ListApp extends App {

    def sum(nums: Int*): Int = {
        if (nums.length == 0) {
            0
        } else {
            nums.head + sum(nums.tail: _*)
        }
    }

    println(sum())
    println(sum(1,2,3,4))
}

\

3 Set

• 元素無序，不能重複
  

package com.scalatest.scala.array

object ListApp extends App {

    val set = scala.collection.mutable.Set[Int]()
    set += 1
    set += (3,2,6,4)

    println(set)
}