scala的Set

set的定义

Set，集合。表示没有重复元素的集合，特点是：唯一，无序。

Set 有可变（mutable）和不可变（immutable）两种类型。不可变 Set 创建后元素不能修改，可变 Set 可对元素进行添加、删除等操作，这两种类型能满足不同场景需求。

/*
* 1.可变：scala.collection.mutable.Set
* 2.不可变：scala.collection.immutable.Set
*/
object set01 {
  def main(args: Array[String]): Unit = {
  
    //它会自动去重，把重复的数据删除
    val set1 = scala.collection.mutable.Set("1345678",100,18.5,100)
    
    // 添加元素
    set1 += 200
    println(set1) // HashSet(200, 1345678, 100, 18.5)

    val set2 = scala.collection.immutable.Set(100,200,100)
  //set2 += 300  报错
    println(set2) // HashSet(100,200)
  }

}

set的常见操作

1.添加元素

val set1 = scala.collection.mutable.Set("语文")
    // 1.添加元素
    set1 += "数学" 
    println(set1) // HashSet(数学, 语文)

2.删除元素

val set1 = scala.collection.mutable.Set("语文","数学")
    set1 -= "语文"
    println(set1) // HashSet(数学)

3.合并。把另一个Set中的数据全部合并过来

union方法

val set2 = scala.collection.mutable.Set("地理","物理")
    val set3 = set1.union(set2) 
    println(set3) // HashSet(数学, 物理, 语文, 地理)

4.查询。看一个元素是否存在

contains方法

val set1 = scala.collection.mutable.Set("语文","数学")
println(set1.contains("数学")) // true 

5.交集

intersect方法

val hobby1 = scala.collection.mutable.Set("唱歌","跳舞")
    val hobby2 = scala.collection.mutable.Set("唱歌","打球")
    val result1 = hobby1.intersect(hobby2)  
    println(result1) //HashSet(唱歌)

6.差集

diff方法

val classes1 = scala.collection.mutable.Set("唱歌","跳舞")
    val classes2 = scala.collection.mutable.Set("唱歌","打球")
    val result2 = classes1.diff(classes2)  
    println(result2) //HashSet(跳舞)

object set02 {
  def main(args: Array[String]): Unit = {

    val set1 = scala.collection.mutable.Set("语文")
    // 1.添加元素
    set1 += "数学"
    println(set1) // HashSet(数学, 语文)

    // 2.删除
    set1 -= "语文"
    println(set1) // HashSet(数学)

    //3.合并
    val set2 = scala.collection.mutable.Set("地理","物理")
    val set3 = set1.union(set2) 
    println(set3) // HashSet(数学, 物理, 语文, 地理)

    //4.查询
    println(set1.contains("数学")) // true  
    
    //5.交集
    val hobby1 = scala.collection.mutable.Set("唱歌","跳舞")
    val hobby2 = scala.collection.mutable.Set("唱歌","打球")
    val result1 = hobby1.intersect(hobby2) 
    println(result1) //HashSet(唱歌)

    //6.差集
    val classes1 = scala.collection.mutable.Set("唱歌","跳舞")
    val classes2 = scala.collection.mutable.Set("唱歌","打球")
    val result2 = classes1.diff(classes2)
    println(result2) //HashSet(跳舞)
  }
}

package set

object set03 {
  def main(args: Array[String]): Unit = {
    //1.
    val set1 = scala.collection.mutable.Set("Java编程思想","Scala实战")

    //2.
    set1 += ("python从入门到实践","MYSQl数据库")
    println(set1)

    //3.
    set1 -= "MYSQl数据库"
    println(set1)

    //4.
    println(set1.contains("python从入门到实践"))
    println(set1)

    //5.
    val set2 = scala.collection.mutable.Set("语文","数学")

    //6.
    val set3 = set1.union(set2)
    println(set3)

    //7.
    val set4 = set1.intersect(set2)
    println(set4)

    //8.
    val set5 = set1.diff(set2)
    println(set5)

  }

}