A trait encapsulates methods and attributes into a single unit. The main purpose of the creation of traits is to enhance reusability by using inheritance.
As we already discussed while doing inheritance, we can extend only a single class but unlike classes, we can mixin any number of traits.
If you are familiar with Java. You can understand traits as a combination of abstract classes and interfaces.
A trait can be created by using a keyword trait. Object creation for a trait is impossible until it is extended by a class where it can be defined completely.
Example:
trait Phone {
val modelNumber: Long
def call(): String
}
class SamsungPhone extends Phone {
override val modelNumber = 12345L
override def call(): String = "I am calling from Samsung phone"
def clickPhotos() = "I am capable of clicking pictures also"
}
class OnePlusPhone extends Phone {
override val modelNumber = 2345L
override def call() = "I can click HD pics"
}
val onePlus7pro = new OnePlusPhone
onePlus7pro.call()
onePlus7pro.modelNumber
In some languages, this feature is available to extend multiple classes in a single class. But this feature is not available in Scala, that's why we needed a trait.
Syntax to extend:
Class A extend ClassB with TraitC with TraitD