Introduction to Java: History, Features, and Applications

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One. Introduction to Java

History and Origins

The "Green Team": Java was originally developed by a team known as the "Green Team" at Sun Microsystems, led by James Gosling.

Initial Name: It was originally called "Oak" (after an oak tree outside Gosling's office), then "Green," and finally renamed to Java.

Original Purpose: While we know it as a web language today, Java was initially designed for consumer electronics (like cable boxes and toasters) to communicate with each other.

The Shift: The boom of the World Wide Web in the mid-nineties shifted Java's focus to the internet because of its portable nature.

Current Stewardship: In twenty ten, Oracle Corporation acquired Sun Microsystems. Today, Oracle manages the standard, though OpenJDK exists as an open-source alternative.

Java Editions

Java is not a "one size fits all" platform; it comes in three main flavors:

One. Java SE (Standard Edition): The core platform used for desktop applications and learning the language. It contains basics like String, ArrayList, and Math.

Two. Java EE (Enterprise Edition): Built on top of SE, this includes tools for large-scale web sites and server-side apps (e.g., banking systems).

Three. Java ME (Micro Edition): A stripped-down version for resource-constrained devices like set-top boxes, old mobile phones, and embedded controllers.

Java was mainly developed to create software for consumer electronic devices that could be controlled by a remote

Features of Java

Two. Object oriented programming language

Abstraction

Encapsulation

Inheritance

Polymorphism

Three. Distributed

Four. Robust

Five. Secure

Six. Portable

Seven. Interpreted

Eight. High Performance

Common Terms of Java:

Java Development Kit:

Java Runtime Environment:

Java Virtual Machine:

Implementation of a Java Applications

Steps

Example Two: Factorial of a Number (Using Loop)

Example Four: Method Usage (Function Call)

Abstraction, Encapsulation and Composition in Java

Advantages of Java Abstraction

Example One: Bank Account (Abstract Data Type Example)

Example Two: Vehicle Abstraction

Abstract class in Java:

Examples:

Example Two: Employee Abstraction

Encapsulation:

Advantages of Encapsulation

Disadvantages of Encapsulation

Example: Encapsulation with Private Data (Error Demonstration)

UE23CS352B: OBJECT ORIENTED ANALYSIS AND DESIGN

Correct Way (Using Encapsulation)

Composition:

Example: Composition (Has-a Relationship)

Step three: Main Class

Output

Why this is Composition

Real-World Meaning

Benefits of using Composition:

Class, Attributes, Methods and Objects

Structure of a class:

Object:

Example of usage of an object in Java:

Explanation of the Example

Java Object: Key Characteristics

Class versus Object in Java

Explanation of the Example

Access Modifiers:

Why Access Modifiers are Important?

Interfaces

Example: P.T.O

Explanation of the Example

Uses of interfaces in Java:

Difference between class and interfaces:

Five. Can we specify an interface method as protected?

Seven. Can a class implement more than one interface?

Eight. Can a class override only some methods of an interface?

Constructors, Destructors and Garbage Collector

Three types of constructors:

Parameterized Constructor

Copy Constructor

Example:

Garbage Collector

finalize() method

Parameter Passing - Value Types and Reference Types

Types of Parameters

Example:

Two. Actual Parameter (Argument)

Example:

Pass by Value (Value Types)

Explanation

Example:

Pass by Reference (Reference Types / Alias)

Explanation

Example:

Understanding Object, Reference, and Variable

Reference

Variable

Example Explanation:

What happens step-by-step?

Method Overloading

Other Names of Method Overloading

Rules for Method Overloading

What is Method Signature?

What is NOT Method Overloading?

Benefits of using Method Overloading

Example:

// Overloading by changing number of parameters

// Overloading by changing data type of parameters

// Overloading by changing order of parameters

// Static method overloading

// Constructor Overloading

public static void main(String[] args) {

Class Attributes and Methods

Instance Methods

Static Methods

Types of Attributes (Variables) in Java

Instance Variables

Static Variables

The static keyword can be used for:

Class variables (or static fields)

Static Method and Attribute: Example

Output:

Explanation:

P.T.O

Output:

Explanation:

Static vs Instance Method

Java Static Block

Why We Use Static Block

Example of Static Block

Explanation:

Static Class

Important Rules

Example of Static Nested Class

Output

Inheritance

IS-A Relationship

Acquiring Properties (Data and Methods)

Superclass (Parent / Base Class)

Subclass (Child / Derived Class)

Reusability of Code

Syntax:

Example: Parent Class (Superclass)

Child Class (Subclass)

Main Class to Test

Output:

Advantages:

Types of Inheritance in Java:

One class inherits another class.

Three. Hierarchical Inheritance

Output:

Method Overriding:

Usage of Java Method Overriding

Rules for Java Method Overriding

Example:

Abstract class

Creation and Usage of Abstract Class in Java

Example of Abstract Class

Abstract vs Interface :

Variables

Constructors

Single Rooted Hierarchy and Object class

Common Interface

Singly-Rooted Hierarchy

Object Class :

. Root of Class Hierarchy

· Package

Some Methods of Object class :

Overriding equals() Method

Overriding toString() Method

Array, List and Stack

Primary Advantages of Collections Framework

Java Collections Framework Hierarchy Diagram

Types of Arrays

Two-Dimensional Array (two D)

Declaration of one D Array

Instantiation (Memory Allocation):

Declaration of two D Array

Instantiation:

Important Points

For-Each Loop in Java

Arrays Class (java.util.Arrays)

Important Points

Syntax (Class Declaration)

Example:

asList()

List in Java

Features of List

Package and Inheritance

Declaration

Implementation Classes of List

Few Common Methods of List

Example: Programming Demo

ArrayList in Java

Declaration

Creating a Generic ArrayList

Primitive Types Not Allowed

Few Common Methods

Example: Programming Demo

Hierarchy of ArrayList in Java Collections Framework

Declaration:

Implemented interfaces :

Hierarchy of List Interface with Vector and Stack in Java Collections Framework

Object Oriented Development Process

Object Oriented Methodology

This approach asks the analyst to determine:

This approach emphasizes how to systematically go about developing a system or application.

This approach asks the analyst to determine:

It focuses on defining:

Stages of Object Oriented Methodology

Analysis

System Design

Class Design

Implementation

System Design

Decisions:

Estimating Performance:

Example: Online Movie Ticket Booking System

Rough Storage Estimate

Making a reuse plan:

In practice:

Libraries:

Qualities of a Good Class Library

Examples include:

Patterns:

Patterns can be applied at different stages of development, including:

Software Architecture Patterns define the overall structure of a system. Examples:

Framework:

In summary:

Frameworks in Java:

Definition

Purpose of Architectural Patterns

Problems Addressed by Architectural Patterns

Common Architectural Patterns:

MVC Architecture:

Architecture:

Example:

Advantages:

MVC Architecture in Java:

Flow of User Request in MVC (Servlet-Based Application)

Simple Code Example (MVC using Servlet)

Overview

This document serves as an introduction to Java, detailing its history, key features, and various editions designed for different applications, such as desktop, enterprise, and embedded systems. It emphasizes the language's evolution and principles of object-oriented programming.

Key Points

1Java was initially developed for consumer electronics before shifting to web applications
2The three editions of Java cater to different development needs, with SE for desktops, EE for enterprises, and ME for mobile
3Key features of Java include simplicity, robustness, security, and portability
4Abstraction and encapsulation are essential concepts in Java programming that improve security and maintainability
5The Java Virtual Machine allows for cross-platform compatibility, executing bytecode regardless of the underlying architecture.

Details

Category: Technology and Engineering

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