We can also provide default values for the properties of the class right inside the constructor - ... Kotlin internally calls the default (implicit) getters/setters of the properties. Using default parameters in a constructor is no different. This way Kotlin knows that the value should be assigned to the second parameter last and not to the first parameter as it would have been if we didn't provide the parameter name. Kotlin functions and constructors can define default arguments, allowing calls to them to skip any argument that has a default value. This is the normal scenario. Here, we have one class called User with two default parameters for the constructor : name and age.By default, name is an empty string and age is equal to 0. Kotlin constructors are bit different than other programming languages. I could not find anything in the documentation, but I was hoping something like this would work: val data = Data(newName()?, newNumber()?) A constructor is the most sophisticated way to initialize the properties of a class. So the line person.lastName = "Jobs" in Kotlin is … //all the 3 values are passed val person1 = Person("Pubg", 25, 100000) //update name and take the default value of age and salary val person2 = Person("John") //take all default value val person3 = Person() Secondary Constructor. class Dog(var breed:String="labrador") : Animal() { } Now if we don’t pass any value for breed it will get “labrador” by default. Default Values in the Constructor. But that does not compile. A constructor is a special kind of function and it is called as soon as the Class object is created. Sometimes, we want our code to be more flexible and reusable to handle default values for optional parameters in our constructors! What the challenge of using Kotlin and JSON boils down to is: We want to use Kotlin data classes for concise code, non-nullable types for null-safety and default arguments for the data class constructor to work when a field is missing in a given JSON. Default values in Kotlin constructor. As JPA requires, @Entity classes should have a default (non-arg) constructor to instantiate the objects when retrieving them from the database. This way, Kotlin can work well with such libraries as Jackson or JPA, which use the no-args constructor to create class instances: class Person(val name: String = "") Yeah, that's a cool feature of Kotlin. We are assigning values to color and breed properties. But is there a way to just use the default value specified in the constructor of the Data class when the values are null? Note that the compiler only uses the properties defined inside the primary constructor for the automatically generated functions. 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