Getting Started with Java on Ubuntu

Compiling Java on Ubuntu can seem like a lot at first, but I’ll break it down step by step for you!

1. Install the Java Development Kit (JDK)

Yes, you need the JDK to compile and run Java programs! Here’s how to install it:

sudo apt update
sudo apt install default-jdk

This command installs the default JDK available in the Ubuntu repositories, which is usually enough for most beginners. You can check if it’s installed correctly by running:

java -version

This should show you the version of Java you installed.

2. Writing Your Java Program

Assuming you have a simple Java program saved as HelloWorld.java:

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

3. Open the Terminal

You can find the Terminal in your applications or by pressing Ctrl + Alt + T.

4. Navigate to Your Java File

You need to go to the directory where your HelloWorld.java file is saved. Use the cd command (which stands for “change directory”). For example:

cd /path/to/your/java/file

Replace /path/to/your/java/file with the actual path.

5. Compiling Your Program

Once you’re in the right directory, compile your Java program using:

javac HelloWorld.java

If there are no errors, this command will create a file named HelloWorld.class, which is your compiled Java bytecode.

6. Running Your Program

Now to run your program, use the following command:

java HelloWorld

Note: You don’t include the .class extension when running the program.

Common Pitfalls

• Make sure your file name matches the class name in your program (case-sensitive).
• If you get a “command not found” error for javac or java, it means JDK is not installed or not added to your PATH.
• Watch out for syntax errors in your Java code—Java is very particular about punctuation and capitalization!

Wrapping It Up!

With these steps, you should be able to compile and run your Java programs on Ubuntu! Don’t stress if you run into issues; it’s all part of the learning process. Keep practicing, and you’ll get the hang of it! Good luck!