Types of Inheritance in Java

March 27, 2023

Are you curious about the Different Types of Inheritance in Java? If so, then this blog is for you! In this article, we’ll cover the different types of inheritance and how they work in Java programming. 

Single-Level Inheritance

Single Level Inheritance is a straightforward form of inheritance that enables you to have one type of object or class "inherit" from another—the Superclass must specify an 'extends' keyword followed by the Subclass name that it wishes to inherit from. When an object inherits properties and behaviour from a Superclass specimen, it can also utilize any methods present in the Superclass. This can be especially helpful in situations where code needs to be reused or consolidated, as it reduces the amount of code needed and offers potential performance optimization when operations are repeated across multiple classes. 

In addition, single-level inheritance also allows you to override constructors from the Parent Class. As with methods, this feature can be useful for centralising certain code sets used across multiple objects and classes. Moreover, polymorphism becomes possible under Single Level Inheritance; with traditional programming languages like Java, polymorphism refers to creating multiple versions of functions that possess similar parameters but behave differently in various scenarios. The ability to create multiple functions (that act upon similar data) can help reduce program execution time and improve overall system performance optimization significantly. 

Multilevel Inheritance

Multilevel inheritance takes this concept a step further. It allows classes to not only inherit from the parent class but also from any other subclass they may have. This means that data and functions can be passed down multiple levels within a single hierarchy. For example, take a base class ‘Animal’ with two subclasses ‘Mammal’ and ‘Reptile’ which both inherit from it; if a new subclass ‘Tiger’ is created which inherits from ‘Mammal’, it will also inherit all the properties and behaviours of ‘Animal’ as well as those specific to Mammals. 

Hierarchical Inheritance

Hierarchical Inheritance is one of the main types of inheritance in Java. It involves creating a superclass and having one or more subclasses, with each subclass extending the superclass. Each subclass can then further be divided into its own subclasses. Essentially, it allows you to structure classes in a hierarchical manner with multiple levels of inheritance.

With Hierarchical Inheritance, you can have one parent class and multiple child classes. Each child class will inherit all the features of its parent class, making it easier to create related classes by reusing the same code and sharing methods and fields. This form of inheritance also allows for polymorphism – when different objects respond differently to the same message or command – which is helpful for creating complex systems that can handle different scenarios.

Multiple Inheritance

Multiple inheritances are when a child class inherits from multiple parent classes. This allows the child class to inherit attributes and methods from each of its parents, allowing for more flexibility in terms of functionality and complexity. However, this also means that there is an increased risk of runtime errors due to conflicts between inherited methods or variables. 

Java does not support multiple inheritances directly, so developers must choose one of two alternative approaches to achieve the same result: interface-based multiple inheritances or composition-based multiple inheritances. 

With interface-based multiple inheritances, a child class can implement several interfaces that represent contracts declaring what must be implemented by concrete classes implementing those interfaces. This allows developers to implement multiple classes in one while maintaining their distinct identities and responsibilities. 

On the other hand, composition-based multiple inheritances involve having one object hold references to other objects which embody all aspects of a given required behaviour in Java architecture by encapsulating them within components container objects known as “composites”.

Hybrid (Virtual) Inheritance

Hybrid inheritance is a combination of multiple types such as single, hierarchical and multilevel inheritances. It enables a subclass to inherit from more than one parent class. This type of inheritance allows a Java Virtual Machine (JVM) to define relationships between related classes and reuse existing code more efficiently. In Subclassing, all classes involved share some kind of relationship between them but do not necessarily have to be related in terms of a hierarchy. 

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Another important point about hybrid inheritance is that it allows for the repetition of base class objects by subclassing them into multiple levels. This comes in handy when developing certain aspects of an application or software project where repeating certain object behaviour or attributes would save development resources and time. Moreover, it allows for runtime polymorphism in Java programs by allowing multiple relations between different classes while still taking advantage of existing code using the same base class objects repeatedly.

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