Java
The classic general-purpose language
Created
1995 by James Gosling at Sun Microsystems
Type
Object-oriented, class-based
Runs on
JVM (Java Virtual Machine)
Current version
Java 21 (LTS, 2023)
Used by
Android, enterprise backends, Big Data
Philosophy
Write once, run anywhere
File extension
.java
Best for
Enterprise apps, Android, Big Data
What is Java?
Java is a class-based, object-oriented programming language created by James Gosling at Sun Microsystems in 1995. It runs on the JVM (Java Virtual Machine), meaning compiled Java bytecode runs on any device with a JVM — Windows, macOS, Linux, Android.
Why Java?
Java is the backbone of enterprise software, Android development, and Big Data processing. Its "write once, run anywhere" philosophy and strong typing make it ideal for large, long-lived systems.
| Feature | Java | Kotlin | Python |
|---|---|---|---|
| Type system | Static | Static | Dynamic |
| Verbosity | Verbose | Concise | Concise |
| Android | Legacy (still supported) | Preferred | Not native |
| Enterprise | Dominant | Growing | Growing |
| Learning curve | Medium | Medium | Easy |
What you'll learn
| Chapter | What you'll know |
|---|---|
| Introduction | What Java is, how it runs |
| Syntax | Variables, types, control flow |
| OOP | Classes, inheritance, interfaces |
| Collections | Lists, maps, sets |
Start with introduction.