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  • Scala 学习

     ArrayBuffer 相当于ArrayList 是有序的。
    val a = ArrayBuffer[Int]() a: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer() scala> a+= 1 res4: a.type = ArrayBuffer(1) scala> a+= 2 res5: a.type = ArrayBuffer(1, 2) scala> a+= 4 res6: a.type = ArrayBuffer(1, 2, 4)
    a+=(3,4,5,7)
    res7: a.type = ArrayBuffer(1, 2, 4, 3, 4, 5, 7)

    a.trimEnd(n)移除a 元素里面最后的n个值
    res7: a.type = ArrayBuffer(1, 2, 4, 3, 4, 5, 7)
    
    scala> a.trimEnd(3)
    
    scala> a
    res9: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(1, 2, 4, 3)

    a.remove(n,m) : 移除第n个下标起的,m个元素

    scala> a
    res11: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(1, 2, 4, 3, 10, 2, 3, 4, 5)
    
    scala> a.remove(2,2)
    
    scala> a
    res13: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer(1, 2, 10, 2, 3, 4, 5)
    

     遍历数组

    res14: Array[Int] = Array(1, 2, 3, 4, 5, 6, 7, 8)
    
    scala> for (i <- 0 until (arr.length,2)){
         | println(arr(i))
         | }
    1
    3
    5
    7

     映射

    scala> val m = Map("a" ->1, "b"->2, "c"->5)
    m: scala.collection.mutable.Map[String,Int] = Map(b -> 2, a -> 1, c -> 5)
    
    scala> for ((k,v) <- m) yield (v,k)
    res18: scala.collection.mutable.Map[Int,String] = Map(2 -> b, 5 -> c, 1 -> a)  
    

     元组

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  • 原文地址:https://www.cnblogs.com/zhanggl/p/4865664.html
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