This article by Analytics Jobs delves into the concept of runtime polymorphism in Java, a crucial aspect of object-oriented programming. It explains its definition, implementation, and benefits, highlighting how it allows objects of different classes to be treated as if they belong to the same class, thereby promoting flexible and maintainable code.
Introduction to Runtime Polymorphism
Another term for Runtime Polymorphism in Java, which started with the concept of method overriding, is Dynamic Method Dispatch. In this scenario, the call to an overridden method will be resolved during code execution (runtime), not at compile time.
Java’s dynamic method dispatch or Runtime Polymorphism in Java is based on inheritance, which happens when there is a parent-child relationship between two or more classes. Now, the parent and child classes—also known as superclasses and subclasses—may have many versions of the same method.
Which version of the identical procedure will be called is unknown. However, the Java Virtual Machine (JVM) easily recognizes the same during runtime, depending on the kind of object being discussed.
Understanding Polymorphism
In Java, the concept of polymorphism allows us to carry out a single action in multiple ways. The Greek terms poly and morphs are the source of the word polymorphism. “Morphs” means shapes, and “poly” implies many. Polymorphism, then, refers to variety.
Compile-time and runtime polymorphism in Java are the two forms of polymorphism found in Java. Java allows for polymorphism through the use of overloading and overriding methods.
Basics of Runtime Polymorphism
Runtime Polymorphism in Java is a concept that allows objects of different classes to be treated as objects of a common class, allowing them to behave differently based on their specific class type. It allows a derived class to override the virtual function of the base class, providing its implementation. The function call is resolved at runtime, depending on the object’s actual type.
Implementation of Runtime Polymorphism in Java
The overriding method is used to achieve Runtime Polymorphism in Java. A subclass can add a method that already exists in its parent class and add additional functionality to it by using the technique known as method overriding. As a result, the base class method is said to be overridden.
“Overriding method” refers to the new method defined in the subclass that has a different implementation but the same prototype as the parent class method. We call the method in the parent class the “Overridden method.”
Usually, we use the base class reference to call the overridden method. After creating a reference to the type base, we’ll use the new keyword to construct an object of the child class.
Therefore, the contents of the reference variable or the object that the base class references to determines which method is called. Thus, the overriding method is called if the reference objects point to an object of the child class. If the reference object has a base class object, then the override method is called. Otherwise, nothing happens.
Advantages of Runtime Polymorphism
Runtime Polymorphism in Java has various advantages, such as encapsulation, polymorphic parameters, flexibility, extensibility, and code reusability. This reduces the amount of code required and increases the modularity of the system by allowing developers to reuse code from the superclass in its subclasses.
It also makes the code more flexible and makes it simpler to add new functionality by allowing objects of different classes to be treated as belonging to the same class.
Additionally, it enables programmers to add new subclasses that override a class’s methods to extend its functionality, which makes it simpler to add new features without changing the old code. It also permits method implementation to be encapsulated in its subclasses, allowing method modifications to be made without impacting other parts of the code.
Common Mistakes and Pitfalls
Among the many benefits of runtime polymorphism in Java are enhanced readability and real-time performance. It is more difficult to implement and makes the code less readable. To access or comprehend subtype behavior, downcasting—casting to a child type or common type to an individual type—is employed. Because it needs explicit compiler input, this is not directly achievable in Java.
One of the main architectural problems with object-oriented programming languages and systems is the fragile base class problem. It happens when a superclass’s subclass uses the superclass in unexpected ways due to poor parent class design, breaking codes even when all requirements are satisfied.
In object-oriented programming languages and systems, this issue is known as a fragile base class problem since the base class developer is unaware of the subclass design. This issue still hasn’t found a solution.
Examples of Runtime Polymorphism in Java
Example 1 and Output
This example demonstrates the creation of two classes, Bike and Splendor, with Splendor overriding the run() method of Bike. The run method is called by the reference variable of the Parent class, causing the subclass method to be invoked at runtime, a phenomenon known as runtime polymorphism.
Example 2 and Output
Imagine a situation in which the class Bank offers a way to obtain the interest rate. Nonetheless, interest rates can vary depending on the bank. For instance, the interest rates offered by SBI, ICICI, and AXIS banks are 8.4%, 7.3%, and 9.7%, respectively.
Best Practices for Utilizing Runtime Polymorphism
To leverage runtime polymorphism in Java effectively, developers should adhere to best practices for writing clean and maintainable code. This includes properly documenting overridden methods, favoring composition over inheritance where appropriate, and applying design patterns such as the Strategy pattern to encapsulate variation.
Conclusion
Runtime Polymorphism in Java, also known as dynamic method dispatch, allows for the development of extensible and adaptable code. This is achieved through abstract classes, interfaces, method overriding, and the Override annotation. Understanding runtime polymorphism in Java is crucial for Java developers as it enhances code quality, maintainability, and software adaptability to changing requirements. It also provides a framework for implementing dynamic method resolution at runtime.
