Classes and objects are fundamental concepts in object-oriented programming, and Scala supports both of them. Here's a brief overview of classes and objects in Scala: 1. Classes: Classes in Scala are similar to classes in other object-oriented programming languages. They can contain fields, methods, and constructors. Here's an example:
class Person(name: String, age: Int) {
def getName(): String = {
name
}
def getAge(): Int = {
age
}
}
val person = new Person("John", 30)
println(person.getName()) // prints "John"
println(person.getAge()) // prints 30
`
In this example, “Person” is a class that has two fields (“name” and “age”) and two methods (“getName” and “getAge”). The constructor for the class is defined implicitly by the parameters passed to the class definition.
2. Objects: Objects in Scala are similar to classes, but they are used to create a single instance of a class. They are often used for utility classes or to create a singleton object. Here’s an example:
``
object MathUtils {
def square(x: Int): Int = {
x * x
}
def cube(x: Int): Int = {
x * x * x
}
}
println(MathUtils.square(3)) // prints 9
println(MathUtils.cube(3)) // prints 27
In this example, "MathUtils" is an object that has two methods ("square" and "cube"). The methods can be called directly on the object, without the need to create an instance of the class.
3. Companion objects: Companion objects are objects that have the same name as a class and are defined in the same file as the class. They can access the private members of the class and provide a way to define static methods or constants for the class. Here's an example:
class Person(name: String, age: Int) {
def getName(): String = {
name
}
def getAge(): Int = {
age
}
}
object Person {
val defaultName = "John"
val defaultAge = 30
def create(): Person = new Person(defaultName, defaultAge)
}
val person = Person.create()
println(person.getName()) // prints "John"
println(person.getAge()) // prints 30
`
In this example, “Person” is a class that has two fields (“name” and “age”) and two methods (“getName” and “getAge”). The companion object “Person” has two fields (“defaultName” and “defaultAge”) and a method (“create”) that creates a new instance of the class with the default values.
Overall, Scala’s support for classes andobjects makes it a powerful and flexible object-oriented language. Classes provide a way to encapsulate data and behavior, while objects provide a way to create singletons or utility classes. Companion objects provide a way to define static methods and constants for a class.