Core Java - Java Essentials

• Java Can be used to develop Smartphone Apps, Websites, Server Side Process's

Development Environment

• Java SDK
• Maven/Gradle (Build Tool)
• IDE (Eclipse, IntelliJ IDEA, etc.,)

Object Oriented Programming

• Objects are all around us. Our brains naturally see the world as an organized collection of various objects.
• Object Oriented Programming is a programming paradigm that organizes software around objects. It is a natural and pragmatic way of modelling the real world.

OOP Benefits

• Software Modularity : The source code for an object can be written, maintained and evolved independently from the code of other objects.
• code re-use : Think of all the libraries.
• Encapsulation : Information Hiding - Hide implementation details from the outside world. Thus increasing the robustness of code.

01. Object

• A software construct that models real world concepts. Everything in this world can be modelled as an object. An object needs to have State and Behaviour

Example: Aircraft Object

• State (Properties) : Maximum Altitude, Maximum Speed, Fuel Capacity, Wingspan
• Behaviour (Capabilities) : Land, Take off, Dump fuel

State is modelled by fields. Behaviour is modelled by methods.

As a best practice, objetcs should remain in control of how the outside world can use them. It must hide away as much implemntation detail as possible and expose only the appropriate behaviour.

02. Class

• A class is a prototype from which objects can be created/instantiated. It contains all the properties and methods that are common to all objects of that type.

Defining a class in Java

• class keyword
• class name
• class body between curly brackets.
• fields (state), methods (behavior) within the body

By default a class is visible only in its own package.

Access Modifier's can be used to make a class more or less visible.

A public class is visible to any other class in the project.

A class can extend another class by using the Extend keyword and can implement one or more interfaces using the implements keyword.

Class Anatomy

• Class access modifier
• class keyword
• class name
• Superclass and/or interfaces
• fields
• methods

Concepts/Topics

• Objects

• Classes and Static Members

• Packages (Code/Classes Organization)

• Modelling State (Instances) & Behaviour (Static Fields & Methods)

• Abstraction

• Encapsulation

• Inheritance

• Polymorphism

• Variables

• Data Types

• Constructors & Initializers

• Operators

• Garbage Collection

• String Processing

• Date Processing

• Control Flow

• Methods

• Parameter Handling

• Language/Java Construct (Enum Types, Nested Classes, etc.,)

• Statement Syntax

• Comments: Line Comments, Block Comments

Various

• Domain Oriented Code
• Run the application from the Command Line without an IDE.