Your First Java Program

Time to write and run your first Java code inside the Maven project you just created.

Create a Java File

1. In IntelliJ, expand the project tree on the left: src → main → java
2. Right-click on the java folder → New → Java Class
3. Enter the name: HelloWorld (capital H, capital W, no spaces)
4. Press Enter — IntelliJ creates the file and opens it

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
        System.out.println("Java is installed and working!");
        System.out.println("You are ready to start learning.");
    }
}

Run the Program

1. Click the green ▶ play button in the gutter (left side, next to public static void main)
2. Click Run 'HelloWorld.main()'
3. The output appears in the Run panel at the bottom of IntelliJ

Hello, World!
Java is installed and working!
You are ready to start learning.

If you see this output, congratulations — your entire setup is working: JDK compiles the code, IntelliJ runs it, and the output is displayed.

Understanding the Code

Try More Code

public class QuickMath {
    public static void main(String[] args) {
        int a = 10;
        int b = 3;
        System.out.println("Sum: " + (a + b));
        System.out.println("Difference: " + (a - b));
        System.out.println("Product: " + (a * b));
        System.out.println("Division: " + (a / b));
        System.out.println("Remainder: " + (a % b));
    }
}

Create this file the same way: right-click java folder → New → Java Class → name it QuickMath → paste the code → click the green play button.

Troubleshooting

Try It Yourself

Exercise 1: Modify HelloWorld.java to print your name, your city, and today's date on separate lines. Run it.

Exercise 2: Create a new Java class called Calculator. Write code that calculates 15% discount on a price of 1299, then adds 18% GST on the discounted price. Print each step.

Exercise 3: Create a class called PersonalInfo that stores your name, age, and email in variables, then prints them in a formatted way: "Name: ..., Age: ..., Email: ..."