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W3S101

Java Overview

Java - Overview

Section titled “Java - Overview”

The Java programming language was initiated by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun’s Java platform (Java 1.0). Oracle acquired Sun in 2010 and continues the development and stewardship of Java.

Java follows a Long-Term Support (LTS) release model, with major LTS versions like Java 8, 11, 17, and 21 receiving updates for several years. This provides stability for enterprise applications. Non-LTS versions are released every six months with new features.

The Java platform has several editions:

  • Java Standard Edition (Java SE): The core platform, providing essential APIs (collections, I/O, networking, basic GUI), the Java Virtual Machine (JVM), and the Java Development Kit (JDK). This tutorial focuses on Java SE.
  • Jakarta EE (formerly Java Enterprise Edition or J2EE): Built on top of Java SE, providing APIs and runtime environment for developing and running large-scale, multi-tiered, reliable, and secure network applications (web services, enterprise beans, etc.).
  • Java Micro Edition (Java ME): A subset of Java SE APIs for developing applications for resource-constrained devices like older mobile phones and embedded systems (less common for new development today).

The core principle of Java remains “Write Once, Run Anywhere” (WORA), thanks to the compilation to platform-independent bytecode executed by the JVM.

Key Features of Java:

Section titled “Key Features of Java:”
  • Object-Oriented: Everything in Java is treated as an object (except primitives), promoting modularity and reusability through concepts like encapsulation, inheritance, and polymorphism.
  • Platform Independent: Compiled Java code (bytecode) runs on any device with a compatible Java Virtual Machine (JVM).
  • Simple: Designed to be relatively easy to learn, especially for programmers familiar with C++ (but omitting complex features like explicit pointers and multiple inheritance of classes).
  • Secure: Features like the JVM’s sandbox model, bytecode verification, and Security Manager provide a secure environment for running applications.
  • Robust: Emphasizes compile-time error checking and runtime checking (e.g., automatic memory management via garbage collection, exception handling) to create reliable software.
  • Multithreaded: Built-in support for concurrent programming, allowing applications to perform multiple tasks simultaneously.
  • High Performance: Modern JVMs use Just-In-Time (JIT) compilation and adaptive optimization techniques to achieve performance close to native compiled languages for many applications.
  • Distributed: Designed with network computing in mind, facilitating the development of distributed applications.
  • Dynamic: Can adapt to evolving environments. Classes are loaded dynamically, and reflection allows examining and manipulating code at runtime.
  • Rich API and Ecosystem: Provides a vast standard library and benefits from a huge ecosystem of third-party libraries and frameworks (like Spring, Hibernate, Apache Commons, etc.).

Brief History:

Section titled “Brief History:”

James Gosling initiated the Java project (initially called Oak) in 1991. Sun Microsystems released Java 1.0 in 1995, promising WORA. Java gained rapid popularity, especially for web applets (now deprecated). In 2006-2007, Sun open-sourced most of Java under the GPL license (OpenJDK). Oracle acquired Sun in 2010 and continues Java’s development, introducing significant features in versions like Java 8 (Lambdas, Streams), Java 9 (Modules), and subsequent releases.

Tools You Will Need:

Section titled “Tools You Will Need:”

To follow this tutorial and develop Java applications, you’ll need:

  • Operating System: A modern OS like Windows 10/11, macOS, or a Linux distribution.
  • Java Development Kit (JDK): This includes the Java compiler (javac), the Java Virtual Machine (JVM), and standard libraries. Download a recent LTS version (e.g., JDK 11, 17, or 21) from Oracle or an OpenJDK provider (like Adoptium, Amazon Corretto, Azul Zulu).
  • Integrated Development Environment (IDE) or Text Editor:
    • IDE (Recommended): Provides features like code completion, debugging, build tools integration, and refactoring. Popular choices include IntelliJ IDEA (Community or Ultimate), Eclipse IDE for Java Developers, and Visual Studio Code with Java extensions.
    • Text Editor: A simpler option like VS Code (without full IDE features), Sublime Text, Atom, or even basic editors like Notepad++ (Windows) or TextEdit (Mac) can be used, but you’ll need to compile and run code manually from the command line.
  • Hardware: A reasonably modern computer (e.g., multi-core CPU, 8GB+ RAM recommended) for a smooth development experience.

This tutorial aims to equip you with the foundational skills to create various Java applications.

Basic Example:

Section titled “Basic Example:”

Here’s the classic “Hello, World!” program in Java:

public class HelloWorld {


    // The main method is the entry point of the application
    public static void main(String[] args) {
        // Print text to the console
        System.out.println("Hello, World!");
    }
}

What is Next?

Section titled “What is Next?”

The next chapter guides you through setting up your Java development environment, including installing the JDK and configuring your system to compile and run Java programs.