Chapter 1: Introduction

Java is one of the most widely used programming languages in the world. Known for its portability, robustness, and extensive ecosystem, Java is a versatile language that runs on a variety of devices, from embedded systems to enterprise servers.

Developed by Sun Microsystems (now owned by Oracle) in 1995, Java has become the foundation of many modern applications.

What is Java?

Java is a high-level, object-oriented programming language designed for flexibility and cross-platform compatibility. It follows the principle of "Write Once, Run Anywhere" (WORA), which means that Java applications can run on any system that has a Java Virtual Machine (JVM).

Java supports various programming paradigms, including functional and concurrent programming, making it suitable for developing scalable applications.

Key features of Java:

- Platform independence (via JVM)

- Object-oriented programming (OOP)

- Automatic memory management (Garbage Collection)

- Multi-threading support

- Secure and robust architecture

- Rich API and vast ecosystem

Java Example

Below is a simple Java program that prints "Hello, World!":

Explanation:

- public class HelloWorld defines a class named HelloWorld.

- public static void main(String[] args) is the entry point of a Java application.

- System.out.println("Hello, World!"); prints the message to the console.

Getting Started with Java

To start coding in Java, follow these steps:

1) Install Java Development Kit (JDK):

Download and install the latest JDK from Oracle or use OpenJDK.

2) Set up an Integrated Development Environment (IDE):

Popular choices include IntelliJ IDEA, Eclipse, and Visual Studio Code.

3) Write and Compile Java Code:

- Save your Java file with .java extension.

- Compile using javac HelloWorld.java.

- Run using java HelloWorld.

Types of Java Applications

Java is used to develop different types of applications, including:

1) Standalone Applications:

Also known as desktop applications, these run on individual computers (e.g., media players, antivirus software).

2) Web Applications:

Java is widely used for building dynamic websites using frameworks like Spring Boot, Servlets, and JSP.

3) Enterprise Applications:

Large-scale applications used in businesses, often built using Java EE (Jakarta EE) for reliability and scalability.

4) Mobile Applications:

Java powers Android app development through the Android SDK.

5) Cloud-Based Applications:

Java supports cloud computing platforms, making it a popular choice for scalable applications.

6) Embedded Systems:

Java is used in devices like smartcards, IoT devices, and microcontrollers.

Java Platforms / Editions

Java is available in different editions, each tailored for specific use cases:

1) Java Standard Edition (Java SE):

- Provides core libraries and APIs for general-purpose programming.

- Includes collections, concurrency, networking, and GUI development.

2) Java Enterprise Edition (Java EE) (Jakarta EE):

- Designed for large-scale, distributed applications.

- Includes APIs for web services, database connectivity (JPA, JDBC), and messaging.

3) Java Micro Edition (Java ME):

- Used for mobile devices, embedded systems, and IoT applications.

- Optimized for limited resources and small footprints.

4) JavaFX:

A modern framework for building rich desktop applications with advanced UI components.

Java continues to be a dominant language in software development due to its versatility, security, and strong community support. Whether you are building web applications, enterprise solutions, or mobile apps, Java offers a reliable and powerful environment for programming.

By mastering Java, developers can create robust and scalable applications across multiple domains.