1.
object Test {
def main(args: Array[String]) {
val sites = Map("runoob" -> "www.runoob.com", "google" -> "www.google.com")
println("runoob："+sites.get("runoob"))
println("baidu:"+sites.get("baidu"))
}}
Test.main(Array())
runoob：Some(www.runoob.com)
baidu:None
defined object Test
2. 模式匹配
object Test {
def main(args: Array[String]) {
val sites = Map("runoob" -> "www.runoob.com", "google" -> "www.google.com")
println("runoob:"+show(sites.get("runoob")))
println("baidu:"+show(sites.get("baidu")))
def show(x:Option[String])=x match{
case Some(s)=>s
case None =>"?"
}
}}
Test.main(Array())
runoob:www.runoob.com
baidu:?
defined object Test
3. getOrElse() 方法来获取元组中存在的元素或者使用其默认的值
object Test {
def main(args: Array[String]) {
val a:Option[Int]=Some(5)
val b:Option[Int]=None
println("a:"+a.getOrElse(0))
println("b:"+b.getOrElse(10))
}}
Test.main(Array())
a:5
b:10
defined object Test
4. isEmpty() 方法
object Test {
def main(args: Array[String]) {
val a:Option[Int] = Some(5)
val b:Option[Int] = None
println("a.isEmpty: " + a.isEmpty )
println("b.isEmpty: " + b.isEmpty )
}
}
Test.main(Array())
a.isEmpty: false
b.isEmpty: true
defined object Test
原文：https://www.cnblogs.com/hapyygril/p/11649735.html