Introduction to Java

Java is a statically-typed, object-oriented programming language that powers everything from Android apps to large-scale enterprise backends (including most systems built with Spring Boot, which we’ll cover later in its own course).

Tip: you don't need to memorize syntax up front. Focus on understanding how a Java program is structured, then build muscle memory through practice.

Your first Java program

Every Java program starts with a class and a main method — this is the entry point the Java Virtual Machine (JVM) looks for when it runs your code.

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

A few things to notice:

• The class name (HelloWorld) must match the filename (HelloWorld.java).
• public static void main(String[] args) is the fixed signature the JVM expects — this exact line rarely changes across projects.
• System.out.println(...) prints a line of text to the console.

What’s next

In the next lesson, we’ll break down Java’s basic syntax rules: variables, data types, and how statements are structured.