Scala学习（集合01）
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文章目录
数组
不可变数组
package learn04
object ScalaCollection
def main(args: Array[String]): Unit =
//数组定义
val arr01=new Array[Int](4)
println(arr01.length)//4
//数组赋值
//修改某个元素的值
arr01(3)=10
val i=10
arr01(i/3)=20
//采用方法的形式修改数组的值
arr01.update(0,1)
//遍历数组
//查看数组
println(arr01.mkString(","))
//普通遍历
for(i<- arr01)
println(i)
//简化遍历
def printx(elem:Int):Unit=
println(elem)
arr01.foreach(printx)
arr01.foreach((x)=>println(x))
arr01.foreach(println(_))
arr01.foreach(println)
4
1,0,0,20
1
0
0
20
1
0
0
20
1
0
0
20
1
0
0
20
1
0
0
20
package learn04
object ScalaCollection
def main(args: Array[String]): Unit =
//创建数组的另外一种方式
val arr1=Array(1,2,3,4)
val arr2=Array(5,6,7,8)
//添加数组元素，创建新数组
val arr3:Array[Int]=arr1:+4
print("arr3:")
println(arr3.mkString(","))
println(arr1 eq arr3)
val arr4:Array[Int]=arr1++:arr2
//添加集合
val arr5:Array[Int]=arr1++arr2
print("arr4:")
println(arr4.mkString(","))
print("arr5:")
println(arr5.mkString(","))
//多维数组
var myMatrix=Array.ofDim[Int](3,3)
myMatrix.foreach(list=>list.foreach(println))
//合并数组
val arr6:Array[Int]=Array.concat(arr1,arr2)
println(arr6.mkString(","))
//创建指定范围的数组
val arr7:Array[Int]=Array.range(0,2)
println(arr7.mkString(","))
val arr8:Array[Int]=Array.fill[Int](5)(-1)
println(arr8.mkString(","))
arr3:1,2,3,4,4
false
arr4:1,2,3,4,5,6,7,8
arr5:1,2,3,4,5,6,7,8
0
0
0
0
0
0
0
0
0
1,2,3,4,5,6,7,8
0,1
-1,-1,-1,-1,-1
可变数组
package learn04
import scala.collection.mutable.ArrayBuffer
object demo01
def main(args: Array[String]): Unit =
val buffer=new ArrayBuffer[Int]
//增加数组
buffer.append(1,2,3,4)
println(buffer.mkString(","))
//修改数据
buffer.update(0,5)
buffer(1)=6
println(buffer.mkString(","))
//删除数据
buffer.remove(2)
println(buffer.mkString(","))
//查询数据
println(buffer(1))
//循环集合
for(i <- buffer)
print(i+" ")
1,2,3,4
5,6,3,4
5,6,4
6
5 6 4
package learn04
import scala.collection.mutable.ArrayBuffer
object demo01
def main(args: Array[String]): Unit =
val buffer1=ArrayBuffer(1,2,3,4)
val buffer2=ArrayBuffer(5,6,7,8)
val buffer3:ArrayBuffer[Int]=buffer1+=5
print("buffer3:")
println(buffer3.mkString(","))
println(buffer1 eq buffer3)
//使用++运算符会产生新的集合数组
val buffer4:ArrayBuffer[Int]=buffer1++buffer2
print("buffer4:")
println(buffer4.mkString(","))
//使用++=运算符会更新之前的集合，不会产生新的数组
val buffer5:ArrayBuffer[Int]=buffer1++=buffer2
print("buffer5:")
println(buffer5.mkString(","))
println(buffer1 eq buffer4)
println(buffer1 eq buffer5)
buffer3:1,2,3,4,5
true
buffer4:1,2,3,4,5,5,6,7,8
buffer5:1,2,3,4,5,5,6,7,8
false
true
可变数组和不可变数组转换
package learn04
import scala.collection.mutable
import scala.collection.mutable.ArrayBuffer
object demo02
def main(args: Array[String]): Unit =
val buffer=ArrayBuffer(1,2,3,4)
val array=Array(4,5,6,7)
//将不可变数组转换为可变数组
val buffer1:mutable.Buffer[Int]=array.toBuffer
//将可变数组转换为不可变数组
val array1:Array[Int]=buffer.toArray
Seq集合
不可变List
package learn04
object demo03
def main(args: Array[String]): Unit =
//Seq集合
val list=List(1,2,3,4)
println("list:",list)
//增加数据
val list1:List[Int]=list:+1
println("list1:",list1)
println(list1 eq list)
list1.foreach(print)
val list2:List[Int]=1+:list
println()
print("list2:")
list2.foreach(print)
val list3:List[Int]=list.updated(1,5)
println()
println(list eq list3)
print("list3:")
list3.foreach(print)
(list:,List(1, 2, 3, 4))
(list1:,List(1, 2, 3, 4, 1))
false
12341
list2:11234
false
list3:1534
package learn04
object demo04
def main(args: Array[String]): Unit =
//Seq集合
val list1=List(1,2,3,4)
//空集合
val list2:List[Nothing]=List()
val nil=Nil
println(list2.mkString(","))
println(list2 eq nil)
//创建集合
val list3:List[Int]=1::2::3::Nil
val list4:List[Int]=list1:::Nil
println(list3.mkString(","))
println(list4.mkString(","))
//连接集合
val list5:List[Int]=List.concat(list3,list4)
println(list5.mkString(","))
//创建一个指定重复数量的元素列表
val list6:List[String]=List.fill[String](3)("a")
println(list6.mkString(","))
true
1,2,3
1,2,3,4
1,2,3,1,2,3,4
a,a,a
可变List
package learn04
import scala.collection.mutable.ListBuffer
object demo05
def main(args: Array[String]): Unit =
//可变集合
val buffer=new ListBuffer[Int]()
//增加数据
buffer.append(1,2,3,4)
//修改数据
buffer.update(1,3)
//删除数据
println(buffer.mkString(","))
buffer.remove(2,2)//从下标2开始，删除2个元素
//遍历集合
buffer.foreach(println)
1,3,3,4
1
3
package learn04
import scala.collection.mutable.ListBuffer
object demo06
def main(args: Array[String]): Unit =
//可变集合
val buffer1=ListBuffer(1,2,3,4)
val buffer2=ListBuffer(5,6,7,8)
//增加数据
val buffer3:ListBuffer[Int]=buffer1:+5
val buffer4:ListBuffer[Int]=buffer1+=5
val buffer5:ListBuffer[Int]=buffer1++buffer2
val buffer6:ListBuffer[Int]=buffer1++=buffer2
println(buffer3.mkString(","))
println(buffer4.mkString(","))
println(buffer5.mkString(","))
println(buffer6.mkString(","))
println(buffer5 eq buffer1)
println(buffer6 eq buffer1)
val buffer7:ListBuffer[Int]=buffer1-2
val buffer8:ListBuffer[Int]=buffer1-=2
println(buffer7 eq buffer1)
println(buffer8 eq buffer1)
1,2,3,4,5
1,2,3,4,5,5,6,7,8
1,2,3,4,5,5,6,7,8
1,2,3,4,5,5,6,7,8
false
true
false
true
可变集合和不可变集合转换
package learn04
import scala.collection.mutable
import scala.collection.mutable.ListBuffer
object demo07
def main(args: Array[String]): Unit =
val buffer=ListBuffer(1,2,3,4)
val list=List(5,6,7,8)
//可变集合转变为不可变集合
val list1:List[Int]=buffer.toList
//不可变集合转变为可变集合
val buffer1:mutable.Buffer[Int]=list.toBuffer
Set集合
不可变Set
package learn04
object demo08
def main(args: Array[String]): Unit =
val set1=Set(1,2,3,4)
val set2=Set(5,6,7,8)
//增加数据
val set3:Set[Int]=set1+5
val set4:Set[Int]=set1+(5,6,7,8)
println(set1 eq set3)
println(set1 eq set4)
set4.foreach(print)
//删除数据
val set5:Set[Int]=set1-2-3
println()
set5.foreach(print)
val set6:Set[Int]=set1++set2
println()
set6.foreach(print)
val set7:Set[Int]=set2++:set1
println()
set7.foreach(print)
println()
println(set6 eq set7)
false
false
51627384
14
51627384
51627384
false
可变Set
package learn04
import scala.collection.mutable
object demo09
def main(args: Array[String]): Unit =
val set1=mutable.Set(1,2,3,4)
val set2=mutable.Set(5,6,以上是关于Scala学习（集合01）的主要内容，如果未能解决你的问题，请参考以下文章