Java has gone through several versions since its initial release in 1995. Below is a detailed breakdown of the major Java versions:

1. Early Versions (Java 1.x)

These were the foundational versions of Java, introducing key concepts like the JVM (Java Virtual Machine), applets, and garbage collection.

  1. Java 1.0 (1996) – First stable version; introduced AWT, applets, and basic Java libraries.
  2. Java 1.1 (1997) – Introduced JDBC (Java Database Connectivity), inner classes, and RMI (Remote Method Invocation).

2. Java 2 (J2SE) Era (1998–2006)

Sun Microsystems rebranded Java as "Java 2" and introduced Standard, Enterprise, and Micro editions.

  1. Java 1.2 (1998, J2SE 1.2) – Swing GUI toolkit, Java Collections Framework, JIT (Just-In-Time) compiler.
  2. Java 1.3 (2000, J2SE 1.3) – HotSpot JVM, Java Sound API.
  3. Java 1.4 (2002, J2SE 1.4) – Exception chaining, regex API, assert keyword, SSL.
  4. Java 5 (2004, J2SE 5.0) – Major update; introduced generics, enhanced for-loop, varargs, enums, autoboxing/unboxing.

3. Modern Java Era (Java SE)

Sun Microsystems was acquired by Oracle in 2010, leading to a new release model.

  1. Java 6 (2006) – Performance improvements, scripting (JSR-223), JDBC 4.0.
  2. Java 7 (2011) – Try-with-resources, diamond operator (<>), switch with Strings.
  3. Java 8 (2014) – Major update; introduced Lambda expressions, Streams API, Optional, new Date-Time API.

4. Rapid Release Cycle (2017-Present)

Oracle adopted a 6-month release cycle for Java SE versions.

  1. Java 9 (2017) – Project Jigsaw (Module System), JShell, HTTP/2 client.
  2. Java 10 (2018) – var keyword for local type inference.
  3. Java 11 (2018, LTS) – Removed JavaFX, introduced HttpClient API.
  4. Java 12 (2019) – Switch expressions (preview).
  5. Java 13 (2019) – Text blocks (preview).
  6. Java 14 (2020) – Records (preview), Pattern matching for instanceof.
  7. Java 15 (2020) – Sealed classes (preview).
  8. Java 16 (2021) – Pattern Matching for instanceof (final).
  9. Java 17 (2021, LTS) – Finalized sealed classes, switch expressions.
  10. Java 18 (2022) – UTF-8 as default encoding.
  11. Java 19 (2022) – Virtual threads (preview).
  12. Java 20 (2023) – Scoped values, structured concurrency.
  13. Java 21 (2023, LTS) – Virtual threads, Sequenced collections, String templates.
  • Java 8 & Java 11 are widely used for enterprise applications.
  • LTS (Long-Term Support) versions: Java 8, 11, 17, and 21.
  • Latest version: Java 21 (as of 2024).
  • Oracle provides updates for LTS versions; non-LTS versions have shorter support windows.

Java Program Structure

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Component Description
1. Package Defines the package the class belongs to (optional).
2. Import Imports external Java libraries or classes (optional).
3. Class A Java program is defined inside a class.
4. Main Method The entry point of a Java application (public static void main(String[] args)).
5. Variables Used to store data (e.g., String name).
6. Object Creation Java uses objects to interact with classes (e.g., Scanner scanner = new Scanner(System.in);).
7. User Input Reads input from the console (scanner.nextLine()).
8. Method Call Calls a method to perform a task (greetUser(name)).
9. Resource Cleanup Closing resources like scanners to free memory.
10. Methods A function inside a class that performs specific actions (greetUser(String userName)).