Java Programming

3.

Object-Oriented Programming (OOP) in Java

3.1.

Core OOP Concepts

3.1.1.

3.1.1.1.

3.1.1.2.

Accessors and Mutators (Getters and Setters)

3.1.2.

3.1.2.1.

3.1.2.2.

IS-A Relationship

3.1.3.

3.1.3.1.

Method Overriding

3.1.3.2.

Dynamic Method Dispatch

3.1.4.

3.1.4.1.

Abstract Classes

3.1.4.2.

3.2.

Classes and Objects

3.2.1.

Defining a Class

3.2.1.1.

3.2.1.2.

3.2.2.

Fields (Instance Variables)

3.2.2.1.

Declaration and Initialization

3.2.2.2.

Access Modifiers

3.2.3.

Methods (Instance Methods)

3.2.3.1.

Method Declaration

3.2.3.2.

Method Invocation

3.2.4.

Creating Objects (Instantiation)

3.2.4.1.

Using the new Keyword

3.2.4.2.

Reference Variables

3.2.5.

The new Keyword

3.2.5.1.

Memory Allocation

3.3.

3.3.1.

Purpose of Constructors

3.3.2.

Default Constructor

3.3.3.

Parameterized Constructors

3.3.4.

Constructor Overloading

3.3.5.

The this Keyword

3.3.5.1.

Referring to Current Object

3.3.5.2.

Constructor Chaining

3.4.

Methods in Depth

3.4.1.

Method Signature

3.4.1.1.

Name, Parameters, Return Type

3.4.2.

Method Overloading

3.4.2.1.

Rules for Overloading

3.4.3.

Passing Arguments

3.4.3.1.

Pass-by-Value Semantics

3.4.3.2.

Effects on Primitives and References

3.4.4.

Returning Values

3.4.4.1.

3.4.4.2.

3.5.

Access Modifiers

3.5.1.

3.5.1.1.

3.5.2.

3.5.2.1.

Package and Subclass Access

3.5.3.

3.5.3.1.

3.5.4.

Default (Package-Private)

3.5.4.1.

3.6.

3.6.1.

The static Keyword

3.6.2.

Static Variables (Class Variables)

3.6.3.

3.6.4.

3.6.5.

3.7.

Inheritance (extends)

3.7.1.

Superclass and Subclass Relationships

3.7.2.

The super Keyword

3.7.2.1.

Accessing Superclass Members

3.7.2.2.

Invoking Superclass Constructors

3.7.3.

Method Overriding

3.7.3.1.

Rules and Annotations

3.7.4.

The @Override Annotation

3.7.5.

The final Keyword

3.7.5.1.

3.7.5.2.

3.7.5.3.

Final Variables (Constants)

3.8.

3.8.1.

Runtime Polymorphism

3.8.1.1.

Dynamic Method Dispatch

3.8.2.

The instanceof Operator

3.8.2.1.

3.9.

3.9.1.

Abstract Classes

3.9.1.1.

Abstract Methods

3.9.1.2.

Instantiation Rules

3.9.2.

Abstract Methods

3.9.2.1.

Declaration and Implementation

3.10.

3.10.1.

Defining Interfaces

3.10.1.1.

Syntax and Structure

3.10.2.

Implementing Interfaces

3.10.2.1.

Multiple Interface Implementation

3.10.3.

Default Methods in Interfaces

3.10.4.

Static Methods in Interfaces

3.10.5.

Marker Interfaces

3.10.5.1.

Purpose and Examples

3.10.6.

Functional Interfaces

3.10.6.1.

Single Abstract Method

3.10.6.2.

Use with Lambdas

3.11.

Nested and Inner Classes

3.11.1.

Member Inner Class

3.11.1.1.

Accessing Outer Class Members

3.11.2.

Static Nested Class

3.11.2.1.

3.11.3.

Local Inner Class

3.11.3.1.

Scope and Usage

3.11.4.

Anonymous Inner Class

3.11.4.1.

Instantiation and Use Cases

3.12.

The Object Class

3.12.1.

Overview and Importance

3.12.2.

equals() Method

3.12.2.1.

Equality Comparison

3.12.3.

hashCode() Method

3.12.3.1.

Hashing and Collections

3.12.4.

toString() Method

3.12.4.1.

String Representation

3.12.5.

3.12.5.1.

3.12.6.

getClass() Method

3.12.6.1.

Runtime Type Information

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