Java Get Started

Setting up Java development environment and writing your first program

🚀 Getting Started with Java

To start Java programming, you need to install Java Development Kit (JDK) and set up your development environment. Then you can write, compile, and run Java programs easily. 


// Your first Java program
public class FirstProgram {
    public static void main(String[] args) {
        System.out.println("Java programming starts here!");
    }
}

Output:

Java programming starts here!

Java Installation

📦

Download JDK

Get Java Development Kit from Oracle

Oracle JDK OpenJDK
⚙️

Install JDK

Run installer and follow instructions

Windows Mac Linux
🔧

Set PATH

Configure environment variables

JAVA_HOME PATH
✅

Verify

Test installation in command prompt

java -version javac -version

🔹 Verify Java Installation

Check if Java is properly installed:

Command Prompt/Terminal Commands: 

# Check Java Runtime Environment
java -version

# Check Java Compiler
javac -version

# Expected output example:
# java version "17.0.1" 2021-10-19 LTS
# javac 17.0.1

Sample Output:

java version "17.0.1" 2021-10-19 LTS

Java(TM) SE Runtime Environment (build 17.0.1+12-LTS-39)

javac 17.0.1

🔹 Choose a Code Editor

Select an editor for writing Java code:

🔸 Recommended IDEs

🔷 IntelliJ IDEA

Professional Java IDE

  • Smart code completion
  • Built-in debugger
  • Project management

🌟 Eclipse

Free and open-source

  • Extensive plugin support
  • Integrated development
  • Version control

💻 VS Code

Lightweight with Java extensions

  • Java Extension Pack
  • Syntax highlighting
  • Debugging support

🔹 Write Your First Program

Create a simple "Hello World" program:

Steps:

  1. Create a file named HelloWorld.java
  2. Write the Java code
  3. Compile the program
  4. Run the program 
// File: HelloWorld.java
public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
        System.out.println("Welcome to Java programming!");
    }
}

Output:

Hello, World!

Welcome to Java programming!

🔹 Compile and Run

Use command line to compile and execute: 

# Step 1: Compile Java source code
javac HelloWorld.java

# Step 2: Run the compiled program
java HelloWorld

# Note: Don't include .class extension when running

What happens:

  • javac compiles .java file to .class (bytecode)
  • java command runs the bytecode on JVM
  • Class name must match filename
  • main() method is the entry point

🔹 Common Beginner Mistakes

Avoid these common errors:

❌ Wrong: 

// Filename: hello.java (lowercase)
public class Hello {  // Class name doesn't match file
    public static void main(String[] args) {
        system.out.println("Hello");  // Wrong case
    }
}

✅ Correct: 

// Filename: Hello.java (matches class name)
public class Hello {
    public static void main(String[] args) {
        System.out.println("Hello");  // Correct case
    }
}

🧠 Test Your Knowledge

What command is used to compile a Java program?