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Java Version Cheat Sheet (Java 8 → Java 22)

javasleep

March 17, 2025

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✅ Java Feature Cheat Sheet

🟧 Java 8 (2014) – The Functional Revolution

• 🔹 Lambda Expressions → (x) -> x * 2
• 🔹 Streams API → list.stream().filter(...).collect(...)
• 🔹 Functional Interfaces → Predicate<T>, Function<T, R>, etc.
• 🔹 Default Methods in interfaces
• 🔹 Optional<T> to avoid null

🟦 Java 9 (2017) – Modularity & Interactivity

• 🔹 Module System → module-info.java
• 🔹 JShell → Java REPL (jshell)
• 🔹 Factory Methods for Collections → List.of(), Set.of(), Map.of()

🟩 Java 10 (2018) – Simplified Syntax

• 🔹 var keyword → Local variable type inference

🟨 Java 11 (2018) – Practical Utilities

• 🔹 New String methods:
  strip(), lines(), repeat()
• 🔹 New File methods:
  Files.readString(), Files.writeString()

🟪 Java 12 (2019) – Functional Stream Enhancements

• 🔹 Collectors.teeing() → Process a stream in two collectors at once

🟫 Java 13 (2019) – Multiline Strings

• 🔹 Text Blocks → """ multiline """ strings

🟥 Java 14 (2020) – Smarter Type Checks

• 🔹 Pattern Matching for instanceof
  → No more casting needed:
  if (obj instanceof String s)

🟦 Java 15 (2020) – Secure Inheritance

• 🔹 Sealed Classes →
  Limit which classes can extend a base class
  sealed class A permits B, C {}

🟩 Java 16 (2021) – Immutable Simplicity

• 🔹 Records →
  Auto-generate immutable data classes
  record Person(String name, int age)

🟨 Java 17 (2021 LTS) – Modern Switch

• 🔹 Pattern Matching in switch
• 🔹 Enhanced Sealed Types
• 🔹 Strong Encapsulation for JDK Internals

🟧 Java 19 (2022) – Concurrency Breakthrough

• 🔹 Virtual Threads (Preview)
  → Lightweight threads for massive concurrency
  Thread.ofVirtual().start(...)

🟦 Java 21 (2023 LTS) – Modern Java Matures

• 🔹 String Templates (Preview) → STR."Hello, \{name}!"
• 🔹 Scoped Values → Safe replacement for ThreadLocal
• 🔹 Sequenced Collections → getFirst(), getLast(), reversed() on List, Set, Map
• 🔹 Structured Concurrency → StructuredTaskScope for managing parallel tasks
• 🔹 Unnamed Variables & Patterns → _ to ignore values cleanly

🟥 Java 22 (2024) – Native Interop & Pattern Power

• 🔹 Foreign Function & Memory API (Preview)
  → Replace JNI, call C functions, manage native memory
• 🔹 Enhanced Pattern Matching & _ Usage
  → Use _ in instanceof, switch, and nested patterns
• 🔹 More switch power: case _ -> now allowed with patterns

🧾 Tip: Use Java 21 as your default LTS baseline

It brings modern programming style, cleaner concurrency, better formatting, and structured error handling.