下面是一个示例,展示了一个函数如何返回一个包含两个不同类型值的Option容器: defgetDetails(id:Int):Option[(String,Int)]={// 从数据库中查询数据valname="John"valage=30Some((name,age))}valdetails=getDetails(1)detailsmatch{caseSome((name,age))=>println("Name: "+name)println("Age: "+age)...
In this example I match the integer values 1 through 12. Any other value falls down to the _ case, which is the catch-all, default case. match expressions are nice because they also return values, so rather than directly printing a string as in that example, you can assign the string ...
Functions that return multiple values Functions that can accept variable arguments Functions that use a value from outside of the function's body None of theseAnswer: C) Functions that use a value from outside of the function's bodyExplanation:...
scopt 4.x provides two styles of constructing a command line option parser: functional DSL and object-oriented DSL. Either case, first you need a case class that represents the configuration: importjava.io.FilecaseclassConfig(foo:Int=-1,out:File=newFile("."),xyz:Boolean=false,libName:String...
首先我们我们对case class 和case object类型对象进行反编译 首先来编译 case class,有如下编译内容: caseclassPerson(age:Int,name:String) 它会产生两个文件如下: Person.class的编译内容如下: import scala.Function1; import scala.Option; import scala.Product; ...
There are no problems in running multiple analysis tools on the same codebase. In fact it could be beneficial as the total set of possible warnings is the union of the inspections of all the enabled tools. The worst case is that the same warnings might be generated by multiple tools. ...
We have already defined values that have a function type. A higher-order function is a function that has a value with a function type as an input parameter or return value. Here’s a good use case for a higher-order function: calling other functions that act on a String, but only if...
另一种更高效的方式是模式匹配。例如:p match { case s: Employee => ... case _ => ...} 8.4 抽象类 和Java一样,可以用abstract关键字来标记不能被实例化的类,通常这是因为它的某个或某几个方法没有被完整定义。 在子类中重写超类的方式时,不需要使用override关键字。
类似于Java中的switch,case后面的类型可以相同,也可以不同。 下面示例中x为相同类型Int: object Demo { def main(args: Array[String]) { println(matchTest(3)) } def matchTest(x: Int): String = x match { case 1 => "one" case 2 => "two" case _ => "many" } } 下面示例中x为任意类...
case _ => "this is match anything other than before cases " //模式匹配的更多通配符 expr match { case List(1,_,_) => " a list with three element and the first element is 1" case List(_*) => " a list with zero or more elements " case Map[_,_] => " matches a map with ...