Polymorphism Comparison

Below list summarizes differences between method overidding and overloading.

Argument list

Overriding: Same method name as well as same data type, number, sequence

Overloading: Same method name but different method signature (data type, number, sequence)

Return type

Overriding: Same or compatible as subtype

Overloading: Same or different (doesn't matter)

Polymorphism type
Overridding: Runtime, object type (not reference variable type) determines which methods should be overridden at runtime
Overloading: Compile time

Binding
Overridding: dynamic => same method signatures make compiler confuse
Overloading: static => private, static and final are restricted to local class scope

Applies to
Overridding: inherited and abstract methods, static methods can be redeclared in subclass but nothing to do with static method in parent class

Overloading: in the same class or subclass, constructor, private, static and final methods

Exceptions

Overridding: can throw any unchecked exceptions. However, the overriding method should not throw checked exceptions that are new or broader than the ones declared by the overridden method.

Overloading: can throw different exceptions

Performance

Overridding: Because done by runtime

Overloading: Better

Class Requirement

Overridding: Two classes (superclass and subclass)

Overloading: within one class

Access Level

Overridding: cannot be restrictive than overridden method of parent class

Overloading: can be restrictive or more accessible