Java 在Scala中使用泛型数据类型值定义映射
我必须在Scala中构造映射,这样我就可以从Java代码调用中收集所有数据。可能的值有Java 在Scala中使用泛型数据类型值定义映射,java,scala,scala-option,Java,Scala,Scala Option,我必须在Scala中构造映射,这样我就可以从Java代码调用中收集所有数据。可能的值有String、Integer、Double和null。有没有办法用Scala来表示这张地图?我试图有如下选择,但不确定它的类型应该是什么 def createScalaMapaFromJavaBean(): Map[String, Option[XXX]] = { val someJavaBean = getMyBeanValues() Map( "key1" -> Option(some
String
、Integer
、Double
和null
。有没有办法用Scala来表示这张地图?我试图有如下选择,但不确定它的类型应该是什么
def createScalaMapaFromJavaBean(): Map[String, Option[XXX]] = {
val someJavaBean = getMyBeanValues()
Map(
"key1" -> Option(someJavaBean.getAgeAsInteger()),
"key2" -> Option(someJavaBean.getSalaryAsDouble()),
"key3" -> Option(someJavaBean.getNameAsString()),
"key4" -> Option(someJavaBean.getSomeFieldValuesAsNull()
)
}
以类型安全的方式执行此操作很容易:
sealed trait MyType
case object MyNil extends MyType
case class MyInt(i: Int) extends MyType
case class MyDouble(d: Double) extends MyType
case class MyString(s: String) extends MyType
然后您的代码变成:
def createScalaMapaFromJavaBean(): Map[String, MyType] = {
val someJavaBean = getMyBeanValues()
Map(
"key1" -> MyInt(someJavaBean.getAgeAsInteger()),
"key2" -> MyDouble(someJavaBean.getSalaryAsDouble()),
"key3" -> MyString(someJavaBean.getNameAsString()),
"key4" -> MyNil
)
}
您可能会像下面这样将数据取回:
map.get(key) match {
case Some(MyInt(i)) => // logic for ints
case Some(MyDouble(d)) => // logic for doubles
case Some(MyString(s)) => // logic for strings
case Some(MyNil) => // logic for nulls
case None => // logic for "key not found"
}
以类型安全的方式执行此操作很容易:
sealed trait MyType
case object MyNil extends MyType
case class MyInt(i: Int) extends MyType
case class MyDouble(d: Double) extends MyType
case class MyString(s: String) extends MyType
然后您的代码变成:
def createScalaMapaFromJavaBean(): Map[String, MyType] = {
val someJavaBean = getMyBeanValues()
Map(
"key1" -> MyInt(someJavaBean.getAgeAsInteger()),
"key2" -> MyDouble(someJavaBean.getSalaryAsDouble()),
"key3" -> MyString(someJavaBean.getNameAsString()),
"key4" -> MyNil
)
}
您可能会像下面这样将数据取回:
map.get(key) match {
case Some(MyInt(i)) => // logic for ints
case Some(MyDouble(d)) => // logic for doubles
case Some(MyString(s)) => // logic for strings
case Some(MyNil) => // logic for nulls
case None => // logic for "key not found"
}
看起来您需要
AnyRef
。您丢失了类型安全性,但看起来您需要AnyRef
。但是你失去了类型安全