For example : Student and Teacher are two different class of persons, but they belong to Person category. Run the class_inheritance.kt file. Similarly, we create objects for the other two classes and invokes their respective member functions. So all these methods are available in every class … Immutable objects are much easier to reason about, especially in multithreaded code. If base class and derived class contains a member function with same name, then we can override the base member function in the derived class using the override keyword and also need to mark the member function of base class with open keyword. generate link and share the link here. constructor is part of the class header: it goes after the class name (and optional type parameters). Writing code in comment? close, link is done using the this keyword: Note that code in initializer blocks effectively becomes part of the primary constructor. you can access its members using only the class name as a qualifier. Kotlin program of overriding the member function –. The open modifier has no effect when added on members of a final class (i.e.. a class with no open modifier). We also need to initialize the base class secondary constructor using the parameters of derived class. The derived class local variables initialize with the respective values and pass the variable name and age as parameters to the Employee class. Like all other OOPS, Kotlin also provides this … Thus, Kotlin doesn't allow multiple inheritance. Di artikel ini, kita akan melanjutkan pelajaran tentang pemrograman berorientasi objek di Kotlin dengan mempelajari abstract classes, interfaces, dan inheritance. Inheritance is one of the key features of object-oriented programming. Android | How to add Radio Buttons in an Android Application? In addition these classes can have … It allows a class to inherit features (properties and methods) from another class. Lets say we have three classes Dog, Cat and Horse. Kotlin has a better solution for classes that are used to hold data/state. Requirement for Data class. In this chapter, we will learn more about Data classes of Kotlin programming language. Here, we instantiate the class CEO and pass the parameter values to the secondary constructor. All classes in Kotlin have a common superclass : Any. Other than this, it does not provide any other functionality. In Kotlin, a class can only inherit one class, which is same as Java. This type of class can be used to hold the basic data apart. It makes our code understandable and extendable. We can use the base class variables and functions in the derived class and can also call functions using the derived class object. During an instance initialization, the initializer blocks are executed in the same order as they appear The derived class local variables initialize with the respective values and pass the variable name and age as … We can create a new base class Employee which contains the common features of the classes so that these three classes can inherit the common features from the base class and can add some special features of their own. Inheritance. Next, we'll define the Admin class in a way so it can be inherited from the User class. Ignoring the ergonomics of data class / property declaration etc, is there a way to deserialise to a class from a known string that isnt the class name? before the secondary constructor body. By default a Kotlin class is closed (sealed) unlike Python which means a class cannot be inherited from unless it is opened (using the open keyword).Note that a class (sub class) inheriting from another class must initialise the constructor of the super class.. This is allowed because a val property essentially declares a get method, How to Change the Background Color of Button in Android using ColorStateList? They cannot be abstract, open, sealed or inner. Big class hierarchies are out of fashion, an item of the book Effective Java written by Joshua Bloch suggests to favor composition over inheritance. The employee class prints the variables names and values to the standard output and transfers the control back to derived class. Inheritance could be used where a group of classes would have some of the behaviours in common. Providing explicit implementations for the componentN () and copy () functions is not allowed. Thus, they are defined for all Kotlin classes. modifiers for overridable members (we call them open) and for overrides: The override modifier is required for Circle.draw(). The class Car inherits the class Vehicle and thus inherit its function run (). Question or issue of Kotlin Programming: Data classes seem to be the replacement to the old-fashioned POJOs in Java. Then, we calls the member function website() using the object wd which prints the string to the standard output. Moreover, It also derives the implementation of standard methods like equals(), hash… In the below program we have called the base class property color and function displayCompany() in derived class using the super keyword. Data classes cannot be abstract, open, sealed, or inner (before 1.1.) Delegation to another constructor of the same class First, we create three class individually and all employees have some common and specific skills. It is quite expectable that these classes would allow for inheritance, but I can see no convenient way to extend a data class. In Kotlin, all classes are final by default. This makes it easier to use Here Student and Teacher could have their own specific behaviours like activity(), profession(), but they have some behaviours like eating, sleeping, etc. This mechanism is known as inheritancein object-oriented programming (OOP). Initialization code can be placed Experience. The derived class inherits all the features from the base class and can have additional features of its own. Please use ide.geeksforgeeks.org, Inheritance allows to inherit the feature of existing class (or base or parent class) to new class (or derived class or child class). edit super: It's fine to inherit from both Rectangle and Polygon, code. If it were missing, the compiler would complain. Example 1 – Kotlin Data Class In the below example we shall define a data class “ Book ” with variables “ name ” and “ price “. If you want to prohibit re-overriding, use final: Overriding properties works in a similar way to overriding methods; properties declared on a superclass It means that, by the time of the base class constructor execution, the properties declared or overridden in the derived class are not yet initialized. Both the header and the body are optional; While learning about inheritance in Kotlin we came to know that every class in Kotlin has a superclass of type Any. The derived.B() is used to call the function B() which prints the variable name inherit from the base class and also prints “Derived class”. If there is no open modifier on a function, like Shape.fill(), declaring a method with the same signature in a subclass is illegal, Before 1.1,data class may only implements interface. After that data classes may extend other classes. Derived class can inherit all the features of base class and can add some features of their own. A member marked override is itself open, i.e. If the derived class contains a primary constructor, then we need to initialize the base class constructor using the parameters of the derived class. By default all Kotlin classes are final and cannot be extended. Employee class having primary constructor with three variables name, age and salary. Kotlin program – Output: Explanation: Here, we instantiate the derived class CEO and passed the parameter values name, age and salary. There are three derived classes webDeveloper, androidDeveloper and iosDeveloper also contains primary constructors and all of them having three variables. 1. We create an object while instantiating the derived class then it is used to invoke the base class and derived class functions. constructor happens as the first statement of a secondary constructor, so the code in all initializer blocks and property initializers is executed Inheritance is an important feature of object oriented programming language. that are then redeclared on a derived class must be prefaced with override, and they must have a compatible type. Note that you can use the override keyword as part of the property declaration in a primary constructor. A class can be marked as a Data class whenever it is marked as ”data”. ; Basic concepts of programming in Kotlin as taught in Unit 1 of this course. But sometimes a class hierarchy can be useful to model the data in an application, if used with attention it can simplify the code and avoid duplication without increasing the complexity. Here, for webDeveloper, we inherit all the features from the base class and its own feature website() in the class. We don't have to declare properties and methods again in Admin, Kotlin will add them automatically. and the class body, surrounded by curly braces. Here, we instantiate the derived class CEO and passed the parameter values name, age and salary. but both of them have their implementations of draw(), so we have to override draw() in Square This is similar to Object in Java. if the class has no body, curly braces can be omitted. constructor etc.) implicitly, and the initializer blocks are still executed: If a non-abstract class does not declare any constructors (primary or secondary), it will have a generated primary If the generated class needs to have a parameterless constructor, default values for all properties have to be specified: brightness_4 But, using inheritance it is lot easier. To denote the supertype from which the inherited implementation is taken, we use super qualified by the supertype name in angle brackets, e.g. We can easily add salary feature without duplicate copies in Employee class. Explanation: We have depicted the properties and behaviours of these classes in the following diagram. The derived.A() is used to call the function A() which prints “Base Class” . All of these three classes have some properties (Data members) and some behaviours (member functions). Note that in this case different secondary constructors can call different constructors of the base type: As we mentioned before, we stick to making things explicit in Kotlin. The Any type is equivalent to the Objecttype we have in Java. Classes, interfaces, and objects are a good starting point for an OOP type system, but Kotlin offers more constructs, such as data classes, annotations, and enums (there is an additional type, named sealed class, that we'll cover later). using the super keyword, or to delegate to another constructor which does that. Delegation to the primary When we inherit a class then all the properties and functions are also inherited. The base class for all classes in Kotlin is Any. To create an instance of a class, we call the constructor as if it were a regular function: Note that Kotlin does not have a new keyword. equals(): Boolean; hashCode(): Int; toString():String; When we create a Koltin data class, Kotlin creates a copy() function too. Note that we do not need to annotate an abstract class or function with open – it goes without saying. Even more specifically, if you declare a companion object inside your class, All of them have some shared features like name, age and also have some special kind of skills. Here, we have a base class and a derived class. Now, we'll declare the administrator class using inheritance. When designing a base class, you should therefore avoid using open members in the constructors, property initializers, and init blocks. So from the Kotlin data class example, we can see how easy it is to create a data class and then use it and all the basic functions are automatically defined by Kotlin. You can also override a val property with a var property, but not vice versa. Classes in Kotlin are declared using the keyword class: The class declaration consists of the class name, the class header (specifying its type parameters, the primary acknowledge that you have read and understood our, GATE CS Original Papers and Official Keys, ISRO CS Original Papers and Official Keys, ISRO CS Syllabus for Scientist/Engineer Exam, Kotlin | Class Properties and Custom Accessors. Multiple constructors can exist on a class. Similarly, we can do for other two classes androidDeveloper and iosDeveloper. One of the things that make Kotlin so awesome is that it encompasses both the OOP and functional programming paradigms—all in one language. The Any type contains the followin… Kotlin Inheritance Example In the below program, we have two parameters in primary constructor of base class and three parameters in derived class. The compiler automatically generates a default getter and setter for all the mutable properties, and a getter (only) for all the read-only properties of the data class. Since 1.1, data classes may extend other classes (see Sealed classes for examples). Explanation: So even if you could come back and say: “well you could use X feature of Kotlin to replicate that” it still needs to be flexible enough to match this common concept that’s available in other languages and platforms. Data classes may only implement interfaces; Since 1.1, data classes may extend to other classes. Familiarity with using the Kotlin Playground for editing Kotlin programs. A data class is similar to a struct in some other languages—it exists mainly to hold some data—but a data class object is still an object. By definition, we all know that inheritance means accruing some properties of the mother class into the child class. Typically the superclass is known as the base class or the parent class and the subclasses are the derived/child class. property initializers declared in the class body: In fact, for declaring properties and initializing them from the primary constructor, Kotlin has a concise syntax: You can use a trailing comma when you declare class properties: Much the same way as regular properties, the properties declared in the primary constructor can be If I inherit from a class, copying does not work correctly, no properties are copied that are in … Data classes can override properties and methods from the interfaces they implement. We can see in the diagram that these three classes have few properties and behaviours common, why not make a generalized class with the common properties and behaviours and let these three classes inherit that generalized class. For data classes, it strongly recommended that you use only read-only properties, making the instances of the data class immutable. To make a class available for extension the open keyword must be used when declaring the class. A new class (subclass) is created by acquiring an existing class's (superclass) members and perhaps redefining their default implementation. Explanation: If you do not want your class It will initialize the local variables and passes values to the base class. in common. If the derived class does not contains primary constructor, we need to call the base class secondary constructor from the secondary constructor of derived class using the super keyword. All classes in Kotlin all automatically inherit from the Any class. The reason why would you want to mark a class as data is to let compiler know that you are creating this class for holding the data, compiler then creates several functions automatically for your data class which would be helpful in managing data. In each of the class, we would be copying the same code for name and age for each character. it may be overridden in subclasses. By using our site, you Inheritance is one of the important features in object-oriented programming. in initializer blocks, which are prefixed with the init keyword. If the primary constructor does not have any annotations or visibility modifiers, the constructor First, instantiate an object for the webDeveloper class and passes the name, age and salary as parameters to the derived class. It will initialize the local variables and pass to the base class Employee using super(name,age). Data class cannot be abstract, inner, open or sealed. If the derived class has no primary constructor, then each secondary constructor has to initialize the base type Kotlin Inheritance; Kotlin Visibility Modifiers; Kotlin Abstract Class; Kotlin Interfaces; Kotlin Nested and Inner Classes; Kotlin Data Class; Kotlin Sealed Class; Kotlin Object; Kotlin Companion Objects; Kotlin Extension Function; Kotlin Operator Overloading; Join our newsletter for the latest updates. Inheritance is one of the key concepts of Object Oriented Programming (OOP). in the class body, interleaved with the property initializers: Note that parameters of the primary constructor can be used in the initializer blocks. In Kotlin, the base class is named as “Any”, which is the super class of the ‘any’ default class declared in Kotlin. Generating External Declarations with Dukat. Inheritance enables code re-usability, it allows to inherit the features from an existing class(base class) to a new class(derived class). mutable (var) or read-only (val). inherit a class which has rule to keep in Proguard keep data class as all the request and response body use data class. Kotlin doesn’t allow a class to inherit from multiple classes because of famous diamond problem. it must override this member and provide its own implementation (perhaps, using one of the inherited ones). sealed classes after 1.1, before 1.1 data classes can only implement interfaces). First let's tell Kotlin that the User class can be inherited. generate an additional parameterless constructor which will use the default values. Code in a derived class can call its superclass functions and property accessors implementations using the super keyword: Inside an inner class, accessing the superclass of the outer class is done with the super keyword qualified with the outer class name: super@Outer: In Kotlin, implementation inheritance is regulated by the following rule: if a class inherits multiple implementations of the same member from its immediate superclasses, How to Add a Floating Action Button to Bottom Navigation Bar in Android? In this task, you create a simple data class and learn about the support Kotlin provides for data classes. With Kotlin’s data classes, you don’t need to write/generate all the lengthy boilerplate code yourself. Deriving a data class from a type that already has a copy (...) function with a matching signature is deprecated in Kotlin 1.2 and is prohibited in Kotlin 1.3. Kotlin Inheriting property and methods from base class – Kotlin with libraries such as Jackson or JPA that create class instances through parameterless constructors. 1,2,3 should be taken care by developer whenever create the class… and provide its own implementation that eliminates the ambiguity. If we want to add salary() feature then we need to copy the same code in all three classes. In particular, the main() program, functions with arguments that return values, variables, data types and operations, as well as if/else statements. Similarly, we can override the property of base class in derived class. So, Kotlin requires explicit While designing an application containing Student, Teacher, etc., if we create a Parent class called Person, we could have the common behaviour… The current behavior of forcing a class name means you need to expose class names to your consumers..? All classes in Kotlin have a common superclass Any, that is the default superclass for a class with no supertypes declared:Any has three methods: equals(), hashCode() and toString(). In the below program, we have two parameters in primary constructor of base class and three parameters in derived class. In Kotlin, you can create a data class to hold the data. Tidak hanya itu, kita juga belajar tentang advanced classes seperti data, enum, nested, dan sealed classes di Kotlin. If any of those properties are used in the base class initialization logic (either directly or indirectly, through another overridden open member implementation), it may lead to incorrect behavior or a runtime failure. If the constructor has annotations or visibility modifiers, the constructor keyword is required, and constructor with no arguments. Sebagai bonus, kita juga akan belajar tentang type aliases. Creating instances of nested, inner and anonymous inner classes is described in Nested classes. Kotlin data class toString() methods. A class and some of its members may be declared abstract. Here, we have a base class Employee marked with open keyword which contains the common properties of the derived classes. During construction of a new instance of a derived class, the base class initialization is done as the first step (preceded only by evaluation of the arguments for the base class constructor) and thus happens before the initialization logic of the derived class is run. A Data Class is like a regular class but with some additional functionalities. to have a public constructor, you need to declare an empty primary constructor with non-default visibility: NOTE: On the JVM, if all of the parameters of the primary constructor have default values, the compiler will inside that class. It allows user to create a new class (derived class) from an existing class (base class). either with override or without it. @ilogico has a good example there.. Additionally, we are often conforming to a set of data contracts defined externally. This Any class provides certain functions are methods. Prerequisites. directly or indirectly through another secondary constructor(s). They can only inherit from other non-data classes (eg. A class in Kotlin can have a primary constructor and one or more secondary constructors. The primary We have data classes in Kotlin that serves this purpose. Inheritance allows code reusability. Then, derived class executes the println() statement and exits. Kotlin data class only focuses on data rather than code implementation. Kotlin Inheritance. using the parameters of the primary constructor. Suppose there are three types of Employee in a company a webDeveloper , an iOSDeveloper and an androidDeveloper. Kotlin Exception Handling | try, catch, throw and finally, Kotlin Environment setup for Command Line, Kotlin Environment setup with Intellij IDEA, Data Structures and Algorithms – Self Paced Course, Ad-Free Experience – GeeksforGeeks Premium, We use cookies to ensure you have the best browsing experience on our website. The visibility of the constructor will be public. keyword can be omitted: The primary constructor cannot contain any code. They can also be used in An abstract member does not have an implementation in its class. So, there is a number of duplicte copies of code in our program and likely to more complex and erratic. Kotlin data class objects have some extra benefits, such as utilities for printing and copying. To create a data class, the following requirements should be met: In the primary constructor atleast one parameter should be present. What I need is something like this: open data class Resource (var id: […] All classes in Kotlin have a common superclass Any, that is the default superclass for a class with no supertypes declared: Any has three methods: equals(), hashCode() and toString(). In this article, you'll learn how inheritance works in Kotlin. Explanation: Inheritance in Data Classes Data classes are final by default. By default, Kotlin classes are final: they can’t be inherited. Dynamic CheckBox in Android with Examples, Arcesium Interview Experience - Senior Software Engineer (3 years experience). Content Providers in Android with Example, Kotlin | Lambdas Expressions and Anonymous Functions, MVC (Model View Controller) Architecture Pattern in Android with Example, Write Interview We can override a non-abstract open member with an abstract one. Even if the class has no primary constructor, the delegation still happens Inheriting a data class from another data class is not allowed because there is no way to make compiler-generated data class methods work consistently and intuitively in case of inheritance. If the derived class contains a primary constructor, then we need to initialize the base class constructor using the parameters of the derived class. The class can also declare secondary constructors, which are prefixed with constructor: If the class has a primary constructor, each secondary constructor needs to delegate to the primary constructor, either The structure of data class is similar to that of a usual Kotlin Class, except that the keyword data precedes the keyword class. To inherit, base class for derived class we should use open keyword in front of base class. But a class can implement many interfaces which we will discuss in next tutorials. Inheritance enables re-usability. To declare an explicit supertype, place the type after a colon in the class header: If the derived class has a primary constructor, the base class can (and must) be initialized right there, of a class (for example, a factory method), you can write it as a member of an object declaration Kotlin program of overriding the member property –. and overriding it as a var additionally declares a set method in the derived class. To make a class inheritable, mark it with the open keyword. the modifiers go before it: For more details, see Visibility Modifiers. It’s called a Data Class. Object-Oriented programming ( OOP kotlin data class inheritance may be declared abstract derived.A ( ) copy... Things that make Kotlin so awesome is that it encompasses both the kotlin data class inheritance the. Now, we 'll declare the administrator class using the parameters of derived class then all properties... All three classes data apart surrounded by curly braces can be marked as ” data ” 1.1 data.... Variables names and values to the Employee class the Admin class in Kotlin have a base class which! Properties and methods from base class member functions ) would allow for inheritance, but I see... Features from the derived classes this mechanism is known as the base class contains constructors. Oriented programming language juga akan belajar tentang type aliases of a final class ( base class Employee using super name. ( base class and three parameters in primary constructor atleast one parameter should be present... Class can be omitted data ” extend to other classes ( eg in front of base and... Structure of data class objects have some shared features like name, and! Name ( and optional type parameters ) Button to Bottom Navigation Bar in with! Functions are also inherited a good example there.. Additionally, we instantiate the body! A derived class CEO and pass the variable name and age for character... Is similar to that of a final class ( subclass ) is used to invoke base! Function website ( ) which prints “ base class – when we inherit all features... ) kotlin data class inheritance created by acquiring an existing class ( i.e.. a class inheritable mark! Jpa that create class instances through parameterless constructors used to hold the data Software Engineer ( 3 years Experience.. I.E.. a class can be omitted Buttons in an Android Application with the respective values and the... Are final: they can’t be inherited as inheritancein object-oriented programming ( OOP ), which is as... Serves this purpose class ” inherit, base class ” their respective member functions ) so. Property of base class and a derived class to call the function (! Class has no body, surrounded by curly braces can be placed in initializer blocks, which is same Java. The data and function displayCompany ( ) using the parameters of derived class local variables initialize with the open has. Sealed, or inner ( before 1.1, data classes in Kotlin can have …,! Classes of Kotlin programming language also inherited values name, age and salary as parameters to Objecttype... Radio Buttons in an Android Application the structure of data contracts defined.! Like name, age and also have some special kind of skills and perhaps redefining their default implementation age each! Inner and anonymous inner classes is described in nested classes common properties of the declaration... Function website ( ) is used to hold the basic data apart and.. For all Kotlin classes are final by default by acquiring an existing class ( i.e.. a can... Output and transfers the control back to derived class code in our and... Be extended the common properties of the class CEO and pass to the derived class and some of its.... No convenient way to extend a data class can be marked as ” data.! Create the class… data class Kotlin with libraries such as utilities for printing and copying link and share the Here... Inner, open or sealed have three classes Dog, Cat and Horse interfaces they implement mother class the... Perhaps redefining their default implementation it encompasses both the OOP and functional programming in! Missing, the compiler would complain the function a ( ) in the class header: it after! Multithreaded code copying the same code in our program and likely to more complex and.! Interfaces they implement of Employee in a way so it can be when. We instantiate the class your consumers.. the Admin class in Kotlin have a base class and class..., all of them have some name and age for each character ( superclass ) members and perhaps redefining default. In Kotlin we came to know that inheritance means accruing some properties of the mother class into child! And copying will initialize the base class and can not be extended values name, age and salary wd... Declare the administrator class using the super keyword with no open modifier ) the open keyword in of. The secondary constructor using the derived class using the Kotlin Playground for editing Kotlin programs data/state., generate link and share the link Here, before 1.1 data classes may implement... Header: it goes after the class has no effect when added on members of a final class i.e... Typically the superclass is known as inheritancein object-oriented programming, the following diagram age as to. Override a val property with a get method and transfers the control back to derived class learn! “ base class ” 'll define the Admin class in derived class inherits all the from. Object Oriented programming language Kotlin dengan mempelajari abstract classes, you 'll learn how inheritance works Kotlin. Own feature website ( ) which prints the variables names and values to the output. Functions or properties from the base class this purpose Button in Android persons, but can. And thus inherit its function run ( ) functions is not allowed nested classes when... See a simple data class only focuses on data rather than code implementation ; if kotlin data class inheritance class and. Without duplicate copies in Employee class prints the variables names and values to the standard output as to... Classes webDeveloper, an iosDeveloper and an androidDeveloper subclass ) is used to the. User class can not be abstract, inner and anonymous inner classes is described in nested classes class. Instantiating the derived class using the derived class, base class Employee marked open! A company a webDeveloper, androidDeveloper and iosDeveloper also contains primary constructors and all employees have special. Override properties and behaviours of these classes in the primary constructor atleast one parameter be! Classes have some extra benefits, such as Jackson or JPA that class. They implement in an Android Application must be used when declaring the class that the User class Navigation! ( ) functions is not allowed prefixed with the init keyword support Kotlin provides for data classes can a. Age but the development skill of all three developers are different 'll define the Admin in... Inherit one class, which is same as Java annotate an abstract one may only implement interfaces since! 1,2,3 should be taken care by developer whenever create the class… data class be omitted classes is in! Data contracts defined externally values to the derived class then it is used to hold data/state a data class like... Class 's ( superclass ) members and perhaps redefining their default implementation and age but the skill! They implement to other classes ( see sealed classes for examples ) duplicate copies in Employee class having constructor! Class for derived class using the Kotlin Playground for editing Kotlin programs simple data class using... Then we need to initialize the base class ) from another class methods base! Classes after 1.1, data classes can not be abstract, open, sealed, inner... Class but with some additional functionalities its own some common and specific.. The key concepts of object Oriented programming ( OOP ) objek di dengan! Do n't have to declare properties and methods again in Admin, Kotlin will add them automatically with... Class executes the println ( ) is created by acquiring an existing class 's ( superclass ) members and redefining! Immutable objects are much easier to use Kotlin with libraries such as utilities for printing and copying the current of. Feature without duplicate copies in Employee class having primary constructor and one or more secondary constructors are two class. Classes may only implement interfaces ; since 1.1, data classes can have … Now, we have base... Modifier ) the key concepts of object Oriented programming language Vehicle and thus inherit its run! Feature of object Oriented programming language multithreaded code age as parameters to the base class and learn the. Class for derived class using the super keyword that make Kotlin so is. By acquiring an existing class ( derived class object vice versa pelajaran tentang pemrograman berorientasi di... Are the derived/child class of forcing a class can be overridden by a with... Declaration in a primary constructor of base class ” with an abstract class or the class! Kotlin Playground for editing Kotlin programs created by acquiring an existing class 's ( superclass ) members and perhaps their. In our program and likely to more complex and erratic – it goes without saying in addition classes. Optional type parameters ) of base class and some behaviours ( member functions or properties from the base class color. Of object Oriented programming language juga akan belajar tentang type aliases the User class declare properties methods. Wd which prints the variables names and values to the base class we the... Some of its members may be declared abstract and age as parameters to derived! Have three classes have some extra benefits, such as utilities for printing copying! Regular class but with some additional functionalities immutable objects are much easier to about. ( data members ) and copy ( ) in derived class get method initialize with the keyword. Two different class of persons, but not vice versa inherit one class, instantiate. An important feature of object Oriented programming ( OOP ) inheritancein object-oriented programming OOP. Not vice versa the child class an abstract class or function with open keyword which contains the properties. Instantiate an object for the componentN ( ) is created by acquiring an existing class 's ( superclass members!