1.1 Your First Java Program

Hello World in Java

Below is a minimal but complete Java program. Type it exactly as shown in your editor and save it as HelloWorld.java.

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

Compiling and Running the Program

Use the terminal or command prompt to navigate to the folder whereHelloWorld.java is saved, then run the following commands:

javac HelloWorld.java
java HelloWorld

If everything is typed correctly and Java is installed properly, your output will look like this:

Hello, World!

Understanding the Program Line by Line

• public class HelloWorld: defines a public class named HelloWorld. The file name must match this class name.
• public static void main(String[] args): entry point of every standalone Java program. The JVM starts execution from this method.
• System.out.println("Hello, World!");: prints a line of text to the console followed by a newline.
• Curly braces { and } group related statements into blocks (class body and method body).
• Each statement ends with a semicolon ;, which tells the compiler where one instruction finishes.