Scala 可变数组ArrayBuffer

package chapter07

import scala.collection.mutable
import scala.collection.mutable.ArrayBuffer

object Test02_ArrayBuffer {
  def main(args: Array[String]): Unit = {
    // 1. 创建可变数组
    val arr1: ArrayBuffer[Int] = new ArrayBuffer[Int]()
    val arr2 = ArrayBuffer(23, 57, 92)

    println(arr1)
    println(arr2)

    // 2. 访问元素
//    println(arr1(0))     // error
    println(arr2(1))
    arr2(1) = 39
    println(arr2(1))

    println("======================")
    // 3. 添加元素
    val newArr1 = arr1 :+ 15  //new一个新的数组进行赋值 不指向同一块地址
    println(arr1)
    println(newArr1)
    println(arr1 == newArr1)
    //可变数组ArrayBuffer   向前追加+=: 向后追加+=
    val newArr2 = arr1 += 19  //引用 对于可变数组 不推荐把操作后的数值的引用赋值给新的数组
    println(arr1)
    println(newArr2)
    println(arr1 == newArr2)
    newArr2 += 13
    println(arr1)

    77 +=: arr1
    println(arr1)
    println(newArr2)
    //append
    arr1.append(36)
    arr1.prepend(11, 76)
    arr1.insert(1, 13, 59) //(位置，*多个数值)
    println(arr1)

    arr1.insertAll(2, newArr1)
    arr1.prependAll(newArr2)

    println(arr1)

    // 4. 删除元素  remove
    arr1.remove(3)
    println(arr1)

    arr1.remove(0, 10)
    println(arr1)

    arr1 -= 13
    println(arr1)

    // 5. 可变数组转换为不可变数组
    val arr: ArrayBuffer[Int] = ArrayBuffer(23, 56, 98)
    val newArr: Array[Int] = arr.toArray
    println(newArr.mkString(", "))
    println(arr)

    // 6. 不可变数组转换为可变数组
    val buffer: mutable.Buffer[Int] = newArr.toBuffer
    println(buffer)
    println(newArr)
  }
}