【第四阶段】kotlin语言的set集合

1.set集合定义，不允许重复元素打印

package Stage4

fun main() {
    //set集合定义，不允许重复元素打印
   // val set : Set = setOf("java","kotlin","c++","java","c++")
    val set= setOf("java","kotlin","c++","java","c++")
    println(set)
}

执行结果

定义重复的元素不会打印
2.set元素获取
set中不能使用[]取值，取而代之的是通过elementAt()获取

package Stage4

fun main() {
    //set集合定义，不允许重复元素打印
   // val set : Set = setOf("java","kotlin","c++","java","c++")
    val set= setOf("java","kotlin","c++","java","c++")
    println(set)
    println(set.elementAt(0))
    println(set.elementAt(9))
}

执行结果

3.处理崩溃越界

elementAtOrElse（）{}当越界后执行{}中逻辑

package Stage4

fun main() {
    //set集合定义，不允许重复元素打印
   // val set : Set = setOf("java","kotlin","c++","java","c++")
    val set= setOf("java","kotlin","c++","java","c++")
    println(set)
    println(set.elementAt(0))
    //println(set.elementAt(9))会发生越界崩溃
    //处理越界崩溃
    println(set.elementAtOrElse(9){"当越界后执行的逻辑"})
}

执行结果

或者使用

set.elementAtOrNull(9)?:"当越界后执行的逻辑"

package Stage4

fun main() {
    //set集合定义，不允许重复元素打印
   // val set : Set = setOf("java","kotlin","c++","java","c++")
    val set= setOf("java","kotlin","c++","java","c++")
    println(set)
    println(set.elementAt(0))
    //println(set.elementAt(9))会发生越界崩溃
    //处理越界崩溃
    println(set.elementAtOrElse(9){"当越界后执行的逻辑"})
    println(set.elementAtOrNull(9)?:"当越界后执行的逻辑")
}

执行结果

4.kotlin语言的可变set集合

package Stage4

fun main() {
    val set= mutableSetOf("java","kotlin","c++")
    set+="c"
    set+="c#"
    set.add("py")
    set-="c"
    set.remove("py")
    println(set)
}

执行结果