scala> def sayHelloWorld : Unit = println("hello, world") def sayHelloWorld: Unit scala> sayHelloWorld hello, world scala> sayHelloWorld() ^ error: Unit does not take parameters 3)return缺省。绝大多数情况下可以省略return,此时方法体中的最后一句代码执行结果即为该方法的返回值,一般仅需在提前终止...
Int]=Map(hadoop->5,spark->10,hbase->7)scala>books.get("hadoop")res0:Option[Int]=Some(5)...
Using this form will result in a form with errors if the input to the form does not match the constraints:val boundForm = userFormConstraints2.bind(Map("bob" -> "", "age" -> "25")) boundForm.hasErrors must beTrueThe out of the box constraints are defined on the Forms object:...
{ # Since com.google.protobuf.Message does not extend Serializable but # GeneratedMessage does, need to use the more specific one here in order # to avoid ambiguity "akka.actor.ActorSelectionMessage" = akka-containers "com.google.protobuf.GeneratedMessage" = proto "akka.remote.DaemonMsgCreate" ...
Since toString on an array does not perform a deep toString, like say scala's List, this is usually a mistake. CollectionIndexOnNonIndexedSeq Checks for calls of .apply(idx) on a Seq where the index is not a literal and the Seq is not an IndexedSeq. Rationale If code which expects ...
nonNull1 { (value, meta) => val MetaDataItem(qualified, nullable, clazz) = meta value match { case bool: Boolean => Right(bool) // Provided-default case case bit: Int => Right(bit == 1) // Custom conversion case _ => Left(TypeDoesNotMatch(s"Cannot convert $value: ${value.as...
The Scala compiler analyzes classes and methods to prevent unnecessary outer captures: unused outer parameters are removed from classes (#4652), and methods not accessing any instance members are made static (#5099). One known limitation is that the analysis is local to a class and does not ...
The problem is that the String split method does not accept a plain string on which to split – rather, it treats the string as a regular expression. Since the pipe character has special meaning in regular expressions (namely “OR”), this has the effect of splitting the string on every ...
The body of the function, a simple multiplication of the input by 2, does not affect the type of the function. The rest of the information is the input types and return type, and so these make up the function type itself. Let’s try using a function type in the REPL, by creating ...
Why Scala does NOT have “static” keyword? What is the main reason for this decision? As we know, Scala does NOT have “static” keyword at all. This is the design decision done by Scala Team. The main reason to take this decision is to make Scala as a Pure Object-Oriented Language...