zoukankan      html  css  js  c++  java
  • scala学习笔记(9): 语法续

    1 不定长参数

    def sum(args: Int*) = {
            var result = 0
            for ( arg <- args) result += arg
            result
    }
    

    2 数组初始化

    val nums = new Array[Int](10)
        nums: Array[Int] = Array(0, 0, 0, 0, 0, 0, 0, 0, 0, 0)
    
    val nums1 = Array(1, 2, 4)
        nums1: Array[Int] = Array(1, 2, 4)
    

    3 变长数组

    import scala.collection.mutable.ArrayBuffer
    
    val b = new ArrayBuffer[Int]()
        //b: scala.collection.mutable.ArrayBuffer[Int] = ArrayBuffer()
    
    b += 1
        // 添加元素到末尾
        res9: b.type = ArrayBuffer(1)
        
    b += (2, 3, 4)
        // 添加多个元素用括号
        res10: b.type = ArrayBuffer(1, 2, 3, 4)
    
    val a = 5 to 10
        a: scala.collection.immutable.Range.Inclusive = Range(5, 6, 7, 8, 9, 10)
    
    b ++= a
        // 添加其他类型
        res11: b.type = ArrayBuffer(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
    

    4 应用于Array、ArrayBuffer的算法

    scala> val a = Array(1, 7, 2, 4, 5)
    //a: Array[Int] = Array(1, 7, 2, 4, 5)
    
    scala> a.sorted
    //res18: Array[Int] = Array(1, 2, 4, 5, 7)
    
    scala> a.sortWith(_ < _)
    //res19: Array[Int] = Array(1, 2, 4, 5, 7)
    
    scala> a.sortWith(_ > _)
    //res20: Array[Int] = Array(7, 5, 4, 2, 1)
    

    5 数组的mkString

    scala> val a = Array(1, 7, 2, 4, 5)
        //a: Array[Int] = Array(1, 7, 2, 4, 5)
    
    scala> a.mkString(" and ")
        //res21: String = 1 and 7 and 2 and 4 and 5
    
    scala> a.mkString("[", ",", "]")
        //res22: String = [1,7,2,4,5]
    

      

  • 相关阅读:
    2020-03-03
    2020-03-02
    2020-03-01
    2020-02-29
    简单自我介绍
    福大软工1816 · 第六次作业
    福大软工1816 · 第五次作业
    python爬虫解决编码问题
    第四次作业-团队介绍
    福大软工1816 · 第三次作业
  • 原文地址:https://www.cnblogs.com/yxzfscg/p/5661592.html
Copyright © 2011-2022 走看看