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Java Get Started

To start programming in Java, you need to set up the development environment, which includes installing the Java Development Kit (JDK), setting up environment variables, and choosing an Integrated Development Environment (IDE) for coding.

Key Topics

1. Downloading and Installing Java

You need to download the Java Development Kit (JDK) to compile and run Java programs.

  • Visit the official Oracle website: Java SE Downloads.
  • Choose the latest JDK version suitable for your operating system.
  • Download and run the installer, following the on-screen instructions.

2. Setting Environment Variables

Setting the JAVA_HOME and updating the PATH environment variable allows you to run Java commands from the command line.

For Windows:

  1. Open Control Panel > System > Advanced system settings.
  2. Click on Environment Variables.
  3. Under System Variables, click New and add JAVA_HOME with the path to your JDK installation (e.g., C:\Program Files\Java\jdk-17).
  4. Edit the Path variable and add %JAVA_HOME%\bin to it.

For macOS and Linux:

  1. Open the terminal.
  2. Edit the .bash_profile or .bashrc file in your home directory.
  3. Add the following lines: 

    export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk-17.jdk/Contents/Home
export PATH=$JAVA_HOME/bin:$PATH
  4. Save the file and run source ~/.bash_profile or source ~/.bashrc to apply the changes.

3. Choosing an IDE

An Integrated Development Environment (IDE) simplifies coding by providing tools like code editors, debuggers, and build automation. Popular Java IDEs include:

  • IntelliJ IDEA: A powerful IDE by JetBrains.
  • Visual Studio Code: A lightweight code editor by Microsoft.
  • Eclipse: An open-source IDE with a rich set of features.
  • NetBeans: An IDE developed by Apache.

4. Installing and Setting Up IDEs

IntelliJ IDEA

  1. Download from the official website: IntelliJ IDEA Downloads.
  2. Choose the Community Edition for free use.
  3. Run the installer and follow the instructions.
  4. Upon first launch, configure the JDK path if prompted.

Visual Studio Code

  1. Download from the official website: VSCode Downloads.
  2. Install the Extension Pack for Java from the Extensions marketplace.
  3. Configure the JDK path in VSCode settings if necessary.

5. Writing Your First Java Program

Create a new Java file named HelloWorld.java in your IDE and add the following code:

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

6. Compiling and Running the Program

Using the Command Line

# Compile the Java program
javac HelloWorld.java

# Run the compiled class file
java HelloWorld

Output:

Hello, World!

Using an IDE

  • In IntelliJ IDEA, click the Run button or press Shift + F10.
  • In VSCode, press F5 to start debugging and running the program.

Explanation: The javac command compiles the Java source file into bytecode, and the java command runs the bytecode on the Java Virtual Machine (JVM). IDEs automate these steps.

Key Takeaways

  • Install the JDK and set environment variables to develop Java applications.
  • Choose an IDE that suits your preferences for efficient coding.
  • Understand how to compile and run Java programs using both the command line and IDEs.
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