Java Introduction

Java is a mature, object-oriented language that runs everywhere — powering server backends, Android apps, big-data tools, and enterprise systems for decades. It's one of the most in-demand skills in software.

Write once, run anywhere

You compile Java source to bytecode, and the JVM (Java Virtual Machine) runs that bytecode on any operating system. The same compiled program runs on Windows, macOS, and Linux unchanged.

Main.java  --(javac)-->  Main.class (bytecode)  --(JVM)-->  runs anywhere

JDK, JRE, JVM

Why learn Java

• Huge demand for backend roles (banks, enterprise, Android).
• Strongly, statically typed — catches many mistakes at compile time.
• A vast ecosystem: Spring Boot, Maven/Gradle, and thousands of libraries.
• Fast, stable, and battle-tested at massive scale.

Modern Java

Java releases every six months, with LTS (Long-Term Support) versions for production. Recent Java has become far more concise — var, records, pattern matching, text blocks, and virtual threads all appear in this course.