/*
* 集合类型 Map:无序可重复 类似于“字典”的概念
* 主要属性:Keys(Set),values
*主要方法:
*
* */
fun main(args: Array<String>) {
//mapof<Key,Value>(Pair(key,value)....)
//显示指定类型,可防止初始化值填写类型的错误
val airports= mapOf<String ,String>(Pair("PVG","浦东"),Pair("SHA","虹桥"),Pair("HGH","萧山"))
//元素计数:size,空否 :isEmpty()
println(airports.size)
//获取某个Key对应的value; get,getOrDefult
print(airports.get("PVG"))
print(airports.getOrDefault("PVG","不存在值"))
//返回所有的Key:keys,所有的值value:values
for (key in airports.keys) {
print(key)//--->>PVG SHA HGH
}
for (v in airports.values) {
print(v)//---->>浦东虹桥萧山
}
//转化为可变:toMutableMap
//mutableMapof<Key,Value>(Pair(key,value),....)
val airports2=airports.toMutableMap()
//添加或更新:下标方法 map变量名[key]=value
airports2["DLC"]="大连机场"
airports2["PVG"]="上海国际机场"
for (mutableEntry in airports2) {
println("${mutableEntry.key},${mutableEntry.value}")
}
//移除元素:remove
airports2.remove("PVG")
for (mutableEntry in airports2) {
println("${mutableEntry.key},${mutableEntry.value}")
}
}