Design Patterns em Scala: Command

Command:Command.scalapackage scala.behavioralimport scala.collection.jcl.ArrayList// Generic/Abstract objectstrait Command[V] { val parameters = new ArrayList[Any]() // throw an exception if invalid parameters def validate() {} def execute() : V def addParameters(params:Any*) { this.parameters ++ params }}trait SimpleCommand extends Command[Any] { def execute() : Any}// Compositetrait CompoundCommand[V] extends Command[ArrayList[V]] { val commands = new ArrayList[Command[V]]() override def validate() { for(command <- commands) command.validate() } override def execute() : ArrayList[V] = { var result = new ArrayList[V]() for(command <- commands) result.add(command.execute()) return result } }trait SimpleCompoundCommand extends CompoundCommand[Any]// Concrete objectscase class MyValue(val str:String)class SomeConcreteCommand extends Command[MyValue] { override def execute() : MyValue = { print("Hello ") return new MyValue("SomeConcreteCommand") }}class AnotherConcreteCommand extends Command[MyValue] { override def execute() : MyValue = { println("Command!") return new MyValue("AnotherConcreteCommand") }}class ComplexConcreteCommand extends CompoundCommand[MyValue] { commands.add(new SomeConcreteCommand()) commands.add(new AnotherConcreteCommand())}object CommandClient extends Application { var c1 = new SomeConcreteCommand() var c2 = new AnotherConcreteCommand() var c3 = new ComplexConcreteCommand() c1.execute() c2.execute() c3.execute()}