Method overloading and method overriding are two concepts in object-oriented programming that involve the use of methods in classes. Here are five key differences between method overloading and method overriding:
Definition:
Method Overloading: Method overloading occurs when a class has multiple methods with the same name but different parameter lists (number, type, or order of parameters). The compiler determines which method to invoke based on the method signature during compile-time.
Method Overriding: Method overriding occurs when a subclass provides a specific implementation for a method that is already defined in its superclass. The method in the subclass has the same signature (name, return type, and parameters) as the method in the superclass.
Inheritance:
Method Overloading: Method overloading is not tied to inheritance. It can occur within the same class or across different classes, without any relationship between them.
Method Overriding: Method overriding is specifically related to inheritance. It involves a method in a subclass providing a specialized implementation of a method defined in its superclass.
Compile-Time vs. Run-Time:
Method Overloading: Overloaded methods are resolved at compile-time. The decision about which method to call is made by the compiler based on the method signature.
Method Overriding: Overridden methods are resolved at runtime. The decision about which method to execute is made dynamically during program execution based on the actual type of the object.
Keyword Usage:
Method Overloading: There is no special keyword used for method overloading. It occurs when multiple methods in the same class or different classes have the same name but different parameters.
Method Overriding: The @Override annotation (in Java) is commonly used to indicate that a method in a subclass is intended to override a method in the superclass. This annotation helps catch errors during compilation if the method signature does not match that of the superclass.
Return Type:
Method Overloading: Method overloading allows methods with the same name but different return types as long as the parameter lists are different. The return type alone does not differentiate overloaded methods.
Method Overriding: Method overriding enforces an identical method signature, including the return type. The return type must be the same or a subtype of the return type in the superclass.
In summary, method overloading involves multiple methods with the same name but different parameter lists, while method overriding involves providing a specific implementation for a method in a subclass that is already defined in its superclass. The key distinctions include when resolution occurs (compile-time vs. runtime), their relationship to inheritance, the use of special keywords, and constraints on return types.