Summary - Pillars of OOPs - Part 2

Polymorphism in Java

Definition:

Polymorphism allows methods to perform different tasks based on the object they act upon. It means "many forms" and lets one interface be used for a general class of actions. The specific action is determined by the actual object.

Types of Polymorphism:

Compile-Time Polymorphism (Static Polymorphism): Achieved through method overloading, resolved during compile time.

Runtime Polymorphism (Dynamic Polymorphism): Achieved through method overriding, resolved during runtime.

Compile-Time Polymorphism:

Method Overloading: Allows a class to have more than one method with the same name but different parameters.

Method Overload Resolution:

The process by which the Java compiler determines which overloaded method to call based on the method signature.

Automatic Promotion:

Java automatically converts a smaller data type to a larger data type during method overloading if no exact match is found.

Runtime Polymorphism:

Method Overriding: Allows a subclass to provide a specific implementation of a method already defined in its superclass.

Dynamic Method Dispatch: Java resolves calls to overridden methods at runtime based on the actual object.

Differences Between Compile-Time and Runtime Polymorphism:

Compile-Time: Achieved by method overloading, resolved at compile time, early binding, less flexible.

Runtime: Achieved by method overriding, resolved at runtime, late binding, more flexible.

Object Class in Java

Definition:

The Object class is the root of the Java class hierarchy. Every class in Java inherits from Object.

Key Methods:

toString(): Returns a string representation of the object.

equals(Object obj): Compares two objects for equality.

hashCode(): Returns an integer hash code value for the object.

getClass(): Returns the runtime class of an object.

Abstraction in Java

Definition:

Abstraction hides the complex implementation details and exposes only the essential features. It can be achieved using abstract classes and interfaces.

Key Concepts:

Abstract Class: Can have both abstract and concrete methods, member variables, constructors, and can implement methods from an interface.

Interface: Can have abstract, default, and static methods, but no constructors or instance variables. A class can implement multiple interfaces.

Anonymous Inner Class:

A class without a name, declared and instantiated in a single expression, often used to override methods of a superclass or implement interface methods on the fly.

Java 8 Interface Enhancements:

Default Methods: Methods in interfaces with a default implementation.

Static Methods: Methods in interfaces that can be called without an instance of the interface.

Enums in Java

Definition:

Enums represent a group of constants in a type-safe manner. They provide a way to define a collection of related values.

Characteristics:

Enums are implicitly final and static.

Enums can have fields, methods, and constructors.

Enums can implement interfaces but cannot extend classes.

By understanding and utilizing these Java concepts, developers can write more flexible, maintainable, and robust code. For more detailed information, refer to the Notion link:

Pillars of OOPs - Part 2⁠

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