Posts in series "Java Basics"

What is Java? A technical introduction to the Java language and platform: the history from Oak in 1991 to Java 21 LTS, the characteristics that define it, where it runs in production, an honest comparison with Python, JavaScript and C#, and the myths worth killing.

The precise difference between JDK, JRE and JVM, why the standalone JRE download is gone, how to install Java 21 on macOS, Windows and Linux, and how to read UnsupportedClassVersionError.

Compare IntelliJ IDEA, Eclipse and VS Code for Java, install one, create your first Java project, understand the src/out layout, and fix the package-does-not-match-directory error.

A token-by-token breakdown of the Java Hello World program: the structure of a .java file, public static void main(String[] args), the filename rule, System.out.println and printf, escape sequences, text blocks and the first compile errors you will hit.

A precise walkthrough of the Java build and run pipeline: javac, the .class file and its bytecode, the classpath, packages, single-file source launch, jshell, runnable jars, and how the JVM loads, verifies and JIT-compiles your code.

A complete guide to Java variables and data types - all 8 primitive types with their real ranges, reference types, stack vs heap, literals, integer overflow, var, final and autoboxing, with every example compiled and run on JDK 21.