Menu
I am learning Scala and Akka and in my recent lookup for a solution, I found something like
case class TotalTaxResult(taxAmount:Double) case object TaxCalculationTimeout What is the difference between the two?
When should I use one over the other?
239
A case class can take arguments, so each instance of that case class can be different based on the values of it's arguments. A case object on the other hand does not take args in the constructor, so there can only be one instance of it (a singleton, like a regular scala object is).
A class can extend another class, whereas a case class can not extend another case class (because it would not be possible to correctly implement their equality).
A case object is like an object , but just like a case class has more features than a regular class, a case object has more features than a regular object. Its features include: It's serializable. It has a default hashCode implementation. It has an improved toString implementation.
A case class has all of the functionality of a regular class, and more. When the compiler sees the case keyword in front of a class , it generates code for you, with the following benefits: Case class constructor parameters are public val fields by default, so accessor methods are generated for each parameter.
A case class can take arguments, so each instance of that case class can be different based on the values of it's arguments. A case object on the other hand does not take args in the constructor, so there can only be one instance of it (a singleton, like a regular scala object is).
If your message to your actor does not need any value differentiation, use a case object. For instance, if you had an actor that did some work, and you, from the outside, wanted to tell it to do work, then maybe you'd do something like this:
case object DoWork ... def receive = { case DoWork => //do some work here } But if you wanted some variation in how the work is done, you might need to redefine your message like so:
case class DoWorkAfter(waitTime:Long) ... def receive = { case class DoWorkAfter(time) => context.system.scheduler.scheduleOnce(time.milliseconds, self, DoWork) case DoWork => //do some work here } If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
