Lesson 1 +10 XP

What is Java?

What is Java?

Java is a popular programming language, created in 1995 by James Gosling at Sun Microsystems. It is used to build apps, websites, games, and software that runs on billions of devices.

Why use Java?

  • Runs on many platforms (Windows, Mac, Linux, Android).
  • Used to build Android apps, desktop apps, and web backends.
  • Has a huge library of ready-made tools.
  • Is one of the most requested programming languages in the world.

How Java runs

Java is compiled to a special format called bytecode. The bytecode runs on a Java Virtual Machine (JVM), which is why the same Java code can run on any device that has a JVM. This idea is often called write once, run anywhere.

Every Java program

Every Java program needs a class, and execution starts inside the main method:

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

Where Java is used

AreaExample
Android appsMobile games and apps
Web serversBackend services for large sites
Desktop appsTools like IntelliJ IDEA
Banking systemsSecure financial software

TL;DR

  • Java was created in 1995 by James Gosling.
  • It runs on many platforms through the Java Virtual Machine.
  • Every program starts in the main method.
  • Java is widely used for Android, web, and enterprise software.