Notes on Differences Between Method Overloading and Method Overriding

Introduction

Method overloading and method overriding are two core concepts in Java's object-oriented programming paradigm. Both mechanisms allow the definition of methods in a way that enhances code reusability and flexibility. However, they differ fundamentally in their implementation and use cases.

Method Overloading

Definition: Method overloading occurs when multiple methods in the same class have the same name but different parameters (different type, number, or both). It is a compile-time polymorphism.

Key Points:

• Same Method Name: All overloaded methods must have the same name.
• Different Parameters: Overloaded methods must differ in the type or number of their parameters.
• Return Type: The return type can be different, but it is not sufficient alone to distinguish overloaded methods.
• Scope: Methods must be in the same class or one must be a subclass of the other.
• Compile-time Resolution: The method to be called is determined at compile time based on the method signature.

Example:

class MathOperations {
    int add(int a, int b) {
        return a + b;
    }

    double add(double a, double b) {
        return a + b;
    }

    int add(int a, int b, int c) {
        return a + b + c;
    }
}

Method Overriding

Definition: Method overriding occurs when a subclass provides a specific implementation of a method already defined in its superclass. It is a runtime polymorphism.

Key Points:

• Same Method Signature: Overridden methods must have the same name, return type, and parameters.
• Inheritance: The method in the superclass must be inherited by the subclass.
• @Override Annotation: It is recommended (but not required) to use the @Override annotation to indicate that a method is being overridden.
• Access Modifiers: The access level of the overridden method cannot be more restrictive than the method in the superclass.