Scala 可变数组ArrayBuffer

 1 package chapter07
 2
 3 import scala.collection.mutable
 4 import scala.collection.mutable.ArrayBuffer
 5
 6 object Test02_ArrayBuffer {
 7   def main(args: Array[String]): Unit = {
 8     // 1. 创建可变数组
 9     val arr1: ArrayBuffer[Int] = new ArrayBuffer[Int]()
10     val arr2 = ArrayBuffer(23, 57, 92)
11
12     println(arr1)
13     println(arr2)
14
15     // 2. 访问元素
16 //    println(arr1(0))     // error
17     println(arr2(1))
18     arr2(1) = 39
19     println(arr2(1))
20
21     println("======================")
22     // 3. 添加元素
23     val newArr1 = arr1 :+ 15  //new一个新的数组进行赋值 不指向同一块地址
24     println(arr1)
25     println(newArr1)
26     println(arr1 == newArr1)
27     //可变数组ArrayBuffer   向前追加+=: 向后追加+=
28     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
29     println(arr1)
30     println(newArr2)
31     println(arr1 == newArr2)
32     newArr2 += 13
33     println(arr1)
34
35     77 +=: arr1
36     println(arr1)
37     println(newArr2)
38     //append
39     arr1.append(36)
40     arr1.prepend(11, 76)
41     arr1.insert(1, 13, 59) //(位置，*多个数值)
42     println(arr1)
43
44     arr1.insertAll(2, newArr1)
45     arr1.prependAll(newArr2)
46
47     println(arr1)
48
49     // 4. 删除元素  remove
50     arr1.remove(3)
51     println(arr1)
52
53     arr1.remove(0, 10)
54     println(arr1)
55
56     arr1 -= 13
57     println(arr1)
58
59     // 5. 可变数组转换为不可变数组
60     val arr: ArrayBuffer[Int] = ArrayBuffer(23, 56, 98)
61     val newArr: Array[Int] = arr.toArray
62     println(newArr.mkString(", "))
63     println(arr)
64
65     // 6. 不可变数组转换为可变数组
66     val buffer: mutable.Buffer[Int] = newArr.toBuffer
67     println(buffer)
68     println(newArr)
69   }
70 }