Introduction to Java

Java is a powerful, object-oriented programming language widely used for building applications, ranging from web and mobile apps to enterprise systems and embedded devices. It follows the "Write Once, Run Anywhere" (WORA) principle, meaning Java programs can run on any platform that supports the Java Virtual Machine (JVM).

Installing Java

Before writing Java programs, you need to install the Java Development Kit (JDK).

Step 1: Download and Install JDK

• Visit the official Oracle website: Download JDK (opens in a new tab)
• Choose the appropriate version for your OS (Windows, macOS, or Linux).
• Install the JDK and set up the JAVA_HOME environment variable.

Step 2: Verify Installation

Open a terminal or command prompt and type:

java -version

If Java is installed correctly, you should see output similar to:

java version "23.0.1" 2025-02-20 LTS
Java(TM) SE Runtime Environment (build 23.0.1+12-LTS-39)
Java HotSpot(TM) 64-Bit Server VM (build 23.0.1+12-LTS-39, mixed mode)

Writing Your First Java Program

Once Java is installed, let's write a simple program.

1. Open a text editor (VS Code, IntelliJ IDEA, or Notepad++).
2. Create a new file named HelloWorld.java.
3. Add the following code:

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

4. Save the file and open a terminal in the same directory.

Compiling and Running Java Code

To compile the program, run:

javac HelloWorld.java

This generates a HelloWorld.class file. Now, run the program:

java HelloWorld

Output:

Hello, World!

Congratulations! You've successfully written and executed your first Java program.