Static Polymorphism vs Dynamic Polymorphism in Programming: A Comprehensive Guide

Polymorphism is a key concept in object-oriented programming that provides flexibility and abstraction, allowing different functions to be used in a similar way according to the object they are acting upon. This article explores two main types of polymorphism: static polymorphism and dynamic polymorphism.

Understanding Polymorphism

Polymorphism allows methods to perform different tasks when acting on different objects. The two primary forms of polymorphism are static polymorphism and dynamic polymorphism.

Static Polymorphism: Compile-Time Polymorphism

Static polymorphism, also known as compile-time polymorphism, is resolved during the compilation stage. This type of polymorphism enables different methods to be determined based on the object type being acted upon.

Method Overloading

Method overloading is a common technique used to achieve static polymorphism. In method overloading, methods within the same class can share the same name but have different parameter types or numbers. This allows for different implementations of the same method based on the arguments provided.

public class MathUtils {
    int add(int a, int b) {
        return a   b;
    }
    double add(double a, double b) {
        return a   b;
    }
}

Java Example of Method Overloading

Operator Overloading

Operator overloading allows programmers to redefine the behavior of operators for user-defined types. This technique extends the functionality of operators to be used in a more meaningful or specialized way within a class.

class ComplexNumber {
    double real, imaginary;
    ComplexNumber(double real, double imaginary) {
          real;
          imaginary;
    }
    // Overloading the addition operator
    public ComplexNumber add(ComplexNumber other) {
        double newReal     ;
        double newImaginary     ;
        return new ComplexNumber(newReal, newImaginary);
    }
}

Java Example of Operator Overloading

Dynamic Polymorphism: Runtime Polymorphism

Dynamic polymorphism, or runtime polymorphism, is resolved at runtime. This type of polymorphism is achieved through method overriding and allows for more complex behaviors. Dynamic polymorphism enables different methods to be chosen based on the object type at runtime.

Method Overriding

Method overriding involves a subclass providing a specific implementation of a method that is already defined in its superclass. The decision about which method to invoke is made based on the object type at runtime, rather than at compile time.

class Animal {
    void makeSound() {
        (Animal sounds);
    }
}
class Dog extends Animal {
    void makeSound() {
        (Bark);
    }
}
class Cat extends Animal {
    void makeSound() {
        (Meow);
    }
}
public class Main {
    public static void main(String[] args) {
        Animal myDog  new Dog();
        Animal myCat  new Cat();
        (); // Outputs: Bark
        (); // Outputs: Meow
    }
}

Java Example of Method Overriding

Key Differences Between Static and Dynamic Polymorphism

Timing: Static polymorphism is determined at compile time, while dynamic polymorphism is determined at runtime. Static polymorphism checks and resolves method calls during the compilation phase, while dynamic polymorphism defers the decision to runtime.

Flexibility: Dynamic polymorphism is more flexible because it can adapt to new subclasses without requiring changes to the existing code. This makes it a powerful tool for creating highly flexible and maintainable code.

Use Cases and Implementation Examples

Static Polymorphism: Method Overloading: Ideal for providing multiple implementations of the same method based on different input parameters. Operator Overloading: Useful for creating custom data types with specialized operator behavior that mimics built-in types.

Dynamic Polymorphism: Method Overriding: Common in inheritance hierarchies where subclasses need to extend or modify the functionality of superclass methods.

Conclusion

Static and dynamic polymorphism serve different purposes and provide distinct benefits in software development. Static polymorphism is ideal for scenarios where method resolution can be determined during compilation, while dynamic polymorphism offers runtime flexibility and adaptability.

Further Reading

Polymorphism in Java: From Oracle Docs Polymorphism in JavaScript