Java Home – Introduction

by
Home
Next

Introduction to Java

Java is a versatile, high-level, object-oriented, and platform-independent programming language. It was developed by Sun Microsystems and released in 1995. Today, Java is maintained by Oracle Corporation and widely used across industries for building desktop applications, web applications, mobile apps, and enterprise systems.

Java’s unique feature of “Write Once, Run Anywhere” (WORA) allows programmers to write code that runs on any device or operating system with a Java Virtual Machine (JVM).

Why Learn Java?

Java is a foundational programming language in computer science and software development. Here’s why learning Java is important:

  1. Platform-Independent: Code runs on different systems (Windows, macOS, Linux) without rewriting.
  2. Widely Used: Java powers Android apps, enterprise software, cloud systems and more.
  3. Beginner-Friendly: Java’s syntax is clean, simple and easy to understand.
  4. Object-Oriented: It uses classes and objects for organized programming.
  5. Job Opportunities: Java developers are always in demand across industries.

Basic Java Workflow

Before you write and run your first Java program, it’s important to understand the process:

  1. Write Code: Code is written in a .java file using any text editor or Integrated Development Environment (IDE) like IntelliJ IDEA, Eclipse, or NetBeans.
  2. Compile Code: The Java compiler (javac) converts the code into bytecode (.class file).
  3. Run Code: The Java Virtual Machine (JVM) interprets and runs the bytecode on the system.

Setting Up Java at HOME

To start coding in Java, you need to install and set up the Java Development Kit (JDK) on your computer. Follow these steps:

Step 1: Install JDK

  1. Go to the Oracle JDK download page.
  2. Download the latest version of the JDK compatible with your system (Windows, macOS, Linux).
  3. Install the JDK by running the downloaded installer.

Step 2: Set JAVA_HOME Environment Variable

The JAVA_HOME variable tells your system where Java is installed. Here’s how you can set it:

On Windows:

  1. Go to System Properties > Advanced System Settings.
  2. Click on Environment Variables.
  3. Under “System Variables,” click New.
  4. Add:
    • Variable name: JAVA_HOME
    • Variable value: Path of the JDK installation (e.g., C:\Program Files\Java\jdk-17).
  5. Save and close.

On macOS/Linux:

  1. Open the terminal.
  2. Edit the ~/.bashrc or ~/.zshrc file (for macOS).
  3. Add the following line:
export JAVA_HOME=/usr/lib/jvm/java-17-openjdk
export PATH=$PATH:$JAVA_HOME/bin

Save the file and run source ~/.bashrc to apply changes.

Step 3: Verify Java Installation

To ensure Java is installed correctly:

  • Open the Command Prompt (Windows) or Terminal (macOS/Linux).
  • Type:
java -version
javac -version
  • If the installation is successful, you will see the version details.

Your First Java Program

Here’s an example of a simple “Hello, World!” program in Java:

Code Example:

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!"); // Prints Hello, World! to the console
    }
}

Explanation:

  1. public class HelloWorld: Declares a class named HelloWorld.
  2. public static void main(String[] args): The entry point of the program.
  3. System.out.println(): Prints output to the console.

Steps to Run the Program:

Save the file as HelloWorld.java.

Open the terminal/command prompt.

Compile the file:

javac HelloWorld.java

Run the program:

java HelloWorld

Output:

Hello, World!

Key Components of Java Development

  1. JDK (Java Development Kit): Contains tools (like javac) needed to compile and run Java code.
  2. JVM (Java Virtual Machine): Runs the Java bytecode on any platform.
  3. JRE (Java Runtime Environment): Includes JVM and libraries required to execute Java programs.

Advantages of Java

  • Cross-Platform: Write code once, run it anywhere.
  • Secure: Java provides a secure execution environment using bytecode verification.
  • Robust: Java handles exceptions and memory management efficiently.
  • Rich API: Java offers a vast collection of built-in libraries.
  • Multi-Threading: Supports concurrent programming for better performance.

Home
Next

Leave a Comment