scala编程入门3：Map与Tupple

最新推荐文章于 2024-05-27 13:54:41 发布

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该博客主要围绕Scala语言展开，详细介绍了Scala中Map的多种创建方式，包括不可变、可变、空的HashMap等，还说明了获取、更新、增加和移除元素的操作，以及遍历Map的方法。此外，还涉及了Tuple的创建、访问和zip操作。

package com.cs.testscala
import scala.collection.mutable
import scala.collection.mutable._
import scala.util.Sorting._

object TestScala {

  def main(args: Array[String]): Unit = {
    // map与分为可变的map和不可变的map
    //1. 创建不可变的map
    val student = Map("zhangsan"->20, "lisi"->21, "wangwu"->20)
//    println(student)
    //2. 创建可变的map
    val student2 = scala.collection.mutable.Map("zhangsan"->20, "lisi"->21, "wangwu"->20)
    //3. 使用tupple的方式创建Map
    val student3 = Map(("zhangsan",20), ("lisi",21), ("wangwu",20))
    //4. 创建空的hashMap
    val student4 = new mutable.HashMap[String,Int]()
    student4("zhangsan") = 20
//    println(student4)
    //5. 获取指定key的值，如果key不存在会报错
    val age = student("zhangsan")
//    println(age)
    //6.使用contains检查key是否存在
    val age1 = if(student.contains("zhangsan")) student("zhangsan") else 0
//    println(age1)
    //7.使用更加简便的方式判断key是否存在并且获取值
    val age2 = student.getOrElse("zhangsan",0)
//    println(age2)
    //8. 更新mutable map
    student2("zhangsan") = 30
//    println(student2)
    //9. 增加多个元素 +=
    student2 += (("liuzi",22),("yangti",23))
//    println(student2)
    //10. 移除元素 -=
    student2 -= (("liuzi"))
//    println(student2)
    //11. 更新不可变的map +/-
    val student5 = student + (("zhougong",20))
//    println(student5)
    //12. 遍历map
//    for((key,value) <- student2) println(key + ":" + value)
    //13. 遍历key
//    for(key <- student2.keySet) println(key)
    //14. 遍历value
//    for(value <- student2.values) println(value)
    //15. 将（key,value）变为(value,key)
    val ss = for((key,value) <- student2) yield (value, key)
    println(ss)

    //16. 创建有序的map
    val student6 = scala.collection.immutable.SortedMap("zhangsan"->20,"lisi"->30,"wangwu"->20)
//    println(student6)
    //17. 创建有插入顺序的map
    val student7 = new mutable.LinkedHashMap[String,Int]
    student7 += ("zhangsan"->20)
    student7 += ("lisi"->20)
//    println(student7)
    //18. 创建tupple
    val t = ("zhangsan", 20)
    //19. 访问tupple
    val key = t._1
    val value = t._2
    //20. zip操作
    val arr = Array("zhangsan", "lisi", "wangwu")
    val arr1 = Array(20,22,23)
    val res = arr.zip(arr1)
    for((key,value) <- res) println(key + ":" + value)
  }

}