![]() As can be seen, such a reverse assignment is less useful to the verge of being problematic on many occasions. Observe that it requires an explicit cast only then it becomes a valid statement. If the situation is reversed, such as follows: Employee employee Įmployee = (Employee)object // Valid, but needs explicit cast Object = employee // This is a valid assignment ![]() This means that, in Java, because the Object class is the parent class or super class of all the classes or, in other words, all classes in Java are, in fact, subclasses of the Object class implicitly or explicitly, a reference variable of the Object type can refer to any class instance in Java. In the case of inheritance hierarchy, a reference object may point to an instance of any classes in the hierarchy, provided the reference variable is declared as the parent class type in the hierarchical tree. Polymorphism by InheritanceĪ reference variable refers to an instance of a class. ![]() In Java, polymorphic reference can be created in two ways: either using inheritance or using interfaces. But, this is acceptable to a large extent and the overhead popularly has a very minor appeal with respect to augmenting the efficiency. However, the deferred commitment of binding in the case of a polymorphic reference gives it an edge over compile time binding in terms of flexibility, but, on the other hand, compromises on the overhead of performance. Both have their uses in object-oriented programming and it is not that one outweighs the other. If the binding is changeable at runtime, as in the case of polymorphic references where the decision of binding is made only during execution, it is called dynamic binding or late binding. When a reference variable is bound to an object that cannot be changed at runtime, or, in other words, the binding of method invocation to a method definition is done at compile time, it is called static binding. This leverages flexibility by giving another dimension of use of the reference variable. Therefore, if a reference can be used to invoke a method at one point in time, it can be dynamically changed to point to another object and invoke some other methods the next time. The rule is too rigid, but polymorphism makes is more flexible by incorporating the idea of “having many forms.” This means that a polymorphic reference guarantees that it can refer to different types of objects at different points in time rather than being stuck with the idea of an exact match for compatibility. This may seem to be the only reliable condition, but that is not exactly true, especially when implementing polymorphism. The qualification of the reference variable to a referred object is determined by its compatibility. The ‘ employee‘ is a reference variable that may refer to an instance of the Employee class. For example, in the following case: Employee employee ![]() It is typically compatible with the class that it refers to. Polymorphic Reference: An OverviewĪ polymorphic reference is a variable that can refer to different types of objects at different points in time. ![]() This article explores some of the intricate details about polymorphism and its implication on object-oriented programming. Although creating polymorphic reference in Java is easy, the concept behind it has a deeper impact on overall programming. In object-oriented methodology, polymorphism enables writing programs that have late binding references. The term typically means that something that can have multiple forms. Polymorphism is one of the fundamental principles of Object-Oriented Software. We may make money when you click on links to our partners. content and product recommendations are editorially independent. ![]()
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