https://devops-monk.com/tutorials/java11/Recent content in Java 11 Tutorial — Complete Guide on Devops MonkHugoen-usMon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java11/collection-factory-methods/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java11/collection-factory-methods/Why Collection Factory Methods? Before Java 9, creating a small immutable collection was tedious: // Java 8 — three lines, two classes, mutable intermediate List<String> names = Collections.unmodifiableList( Arrays.asList("Alice", "Bob", "Charlie") ); // Java 8 — even worse for Map Map<String, Integer> scores = new HashMap<>(); scores.put("Alice", 90); scores.put("Bob", 85); Map<String, Integer> immutableScores = Collections.unmodifiableMap(scores); JEP 269 (Java 9) introduced static factory methods that create truly immutable collections with a single expression:https://devops-monk.com/tutorials/java11/files-io-api/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java11/files-io-api/The Problem: File IO Boilerplate Reading a file’s content in Java 8 required several lines of boilerplate, even for simple tasks: // Java 8 — read entire file as String String content; try (var reader = new BufferedReader(new FileReader("config.txt"))) { content = reader.lines().collect(Collectors.joining("\n")); } // Java 8 — write a String to a file try (var writer = new BufferedWriter(new FileWriter("output.txt"))) { writer.write(content); } Java 11 reduced this to one-liners.https://devops-monk.com/tutorials/java11/flight-recorder/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java11/flight-recorder/What Is Java Flight Recorder? Java Flight Recorder (JFR) is a low-overhead, always-on profiling and diagnostics framework built into the JVM. It was a commercial feature of Oracle JDK until JEP 328 (Java 11) open-sourced it as part of OpenJDK. JFR collects data about JVM internals and application behaviour — method profiling, allocation, GC pauses, thread states, I/O, lock contention — with a typical overhead of 1–2% in production. This makes it fundamentally different from traditional profilers (JProfiler, YourKit): those profilers cause 10–50% overhead, making them impractical for production.https://devops-monk.com/tutorials/java11/garbage-collection/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java11/garbage-collection/GC Changes Across Java 9–11 Release Change JEP Java 9 G1GC becomes the default GC JEP 248 Java 9 Unified GC logging (-Xlog:gc*) JEP 271 Java 10 Parallel Full GC for G1 JEP 307 Java 10 Application Class-Data Sharing (AppCDS) JEP 310 Java 11 Epsilon: No-Op GC JEP 318 Java 11 ZGC: Scalable Low-Latency GC (experimental) JEP 333 G1GC as Default (JEP 248, Java 9) G1 (Garbage-First) replaced Parallel GC as the default on systems with ≥2 CPUs and ≥2 GB heap.https://devops-monk.com/tutorials/java11/http-client-api/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java11/http-client-api/Why a New HTTP Client? HttpURLConnection — Java’s HTTP API since Java 1.1 — has deep design problems: Mutable shared state makes it error-prone in multithreaded code No built-in HTTP/2 support No built-in async; non-blocking requires manual thread management Clunky API: setDoOutput(true), getOutputStream(), connect() in sequence No support for reactive streams JEP 321 (Java 11) standardised the HTTP Client API that was incubating since Java 9. The new API lives in java.https://devops-monk.com/tutorials/java11/java11-overview/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java11/java11-overview/Why Java 11 Matters Java 8 was released in March 2014. It dominated enterprise Java for nearly a decade, but it misses a decade’s worth of language improvements, API modernisation, JVM advances, and security hardening. Java 11 (September 2018) is the first Long-Term Support release after Java 8, and it packages three releases of evolution into a single supported baseline. For most teams the question is not whether to upgrade, but how.https://devops-monk.com/tutorials/java11/production-best-practices/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java11/production-best-practices/Production Readiness Checklist [ ] JDK distribution chosen and version pinned [ ] Heap and Metaspace sized correctly [ ] GC selected and tuned for your workload [ ] Container-aware JVM flags set [ ] AppCDS archive built for faster startup [ ] JFR always-on recording configured [ ] GC logging enabled with rotation [ ] Security-related algorithms locked down [ ] Thread and connection pool sizes verified [ ] JVM exit flags prevent silent crashes Baseline JVM Flags for Java 11 Start with these flags and tune from here:https://devops-monk.com/tutorials/java11/migration-guide/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java11/migration-guide/Migration Overview Migrating from Java 8 to Java 11 is the most common Java upgrade scenario. The migration has two distinct phases: Make it compile and run — fix incompatibilities introduced by Java 9–11 Modernise the code — adopt var, List.of(), String.isBlank(), and other new APIs Phase 1 is mandatory and blocks the upgrade. Phase 2 is optional and can happen incrementally. This guide focuses entirely on Phase 1. The 10-Step Migration Checklist [ ] 1.https://devops-monk.com/tutorials/java11/module-system/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java11/module-system/The Problem JPMS Solves Before Java 9, the JDK had no real notion of encapsulation at the library level. public meant accessible to everyone — including internal JDK classes like sun.misc.Unsafe and com.sun.internal.*. Large codebases suffered from: No reliable encapsulation: Any public class in any JAR was reachable from any other JAR. Classpath hell: Duplicate or conflicting classes from different JARs led to unpredictable behaviour. Monolithic JDK: The entire 60+ module JDK had to ship with every application.https://devops-monk.com/tutorials/java11/string-methods/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java11/string-methods/New String Methods in Java 11 Java 11 added six new instance methods to java.lang.String. None require any imports — they are part of the standard String class. Method Returns Description isBlank() boolean True if string is empty or contains only whitespace lines() Stream<String> Stream of lines split by line terminators strip() String Removes leading and trailing Unicode whitespace stripLeading() String Removes leading Unicode whitespace only stripTrailing() String Removes trailing Unicode whitespace only repeat(int n) String Returns the string repeated n times isBlank() Returns true if the string is empty or contains only whitespace characters as defined by Character.https://devops-monk.com/tutorials/java11/removed-deprecated-apis/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java11/removed-deprecated-apis/Removal Timeline API Deprecated In Removed In JEP Java EE modules (JAXB, JAX-WS, etc.) Java 9 Java 11 JEP 320 JavaFX Bundled with Java 9 Unbundled in Java 11 — Nashorn JavaScript Engine Java 11 Java 15 JEP 335 Pack200 tools and API Java 11 Java 14 JEP 336 javah tool Java 9 Java 10 JEP 313 sun.misc.BASE64Encoder/Decoder Java 8 Java 11 Encapsulation Thread.destroy(), Thread.stop(Throwable) Old Java 11 — Applet API Java 9 Java 17 JEP 289 Java EE Modules Removed (JEP 320) The six Java EE modules that shipped with Java SE 6–10 were removed from Java 11.https://devops-monk.com/tutorials/java11/security-tls13/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java11/security-tls13/Security Improvements Across Java 9–11 JEP Release Feature JEP 287 Java 9 SHA-3 hash algorithms JEP 273 Java 9 DRBG-based SecureRandom JEP 288 Java 9 Disable SHA-1 certificates JEP 324 Java 11 Key Agreement with Curve25519 and Curve448 JEP 329 Java 11 ChaCha20 and Poly1305 cryptographic algorithms JEP 332 Java 11 Transport Layer Security (TLS) 1.3 JEP 181 Java 11 Nest-Based Access Control TLS 1.3 (JEP 332) TLS 1.3 is the current version of the Transport Layer Security protocol, finalised in RFC 8446 (August 2018).https://devops-monk.com/tutorials/java11/java11-setup/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java11/java11-setup/Choosing a JDK Distribution Java 11 is available from multiple OpenJDK distributions. All are TCK-certified and binary-compatible; the differences are support timelines and add-ons. Distribution Vendor Java 11 Support Until Notes Eclipse Temurin Adoptium Oct 2027 Community standard, most downloaded Amazon Corretto Amazon Aug 2024 (free), extended via AWS Best choice for AWS workloads Azul Zulu Azul Systems 2026+ Wide platform coverage Microsoft Build of OpenJDK Microsoft 2024 Best for Azure Oracle JDK 11 Oracle Oct 2024 (free LTS) Commercial support until 2026 GraalVM CE 21 Oracle/GraalVM Community Native image + polyglot; JDK 21-based For most teams: Eclipse Temurin 11 — widest platform support, longest free support window, backed by a vendor-neutral foundation.https://devops-monk.com/tutorials/java11/stream-optional-enhancements/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java11/stream-optional-enhancements/Stream API — New Methods (Java 9) Java 9 added four new instance methods to Stream<T>. All are terminal-ish or intermediate operations that make common patterns expressible without workarounds. takeWhile(Predicate) Returns elements from the beginning of the stream as long as the predicate holds, then stops. The first element that fails the predicate (and all subsequent elements) are discarded. Stream.of(1, 2, 3, 4, 5, 1, 2) .takeWhile(n -> n < 4) .https://devops-monk.com/tutorials/java11/tooling-jshell-jlink/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java11/tooling-jshell-jlink/Overview Java 9 and 11 added three tools that change how you write, test, and deploy Java code: Tool JEP Release Purpose JShell JEP 222 Java 9 Interactive REPL for Java code jlink JEP 282 Java 9 Build minimal custom JRE images Single-file programs JEP 330 Java 11 Run .java files directly JShell — Interactive Java REPL JShell is Java’s Read-Eval-Print Loop: a command-line tool for evaluating Java expressions, statements, methods, and classes interactively, without creating a project.https://devops-monk.com/tutorials/java11/var-keyword/Mon, 04 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/java11/var-keyword/What var Does var is a reserved type name (not a keyword) introduced in Java 10 (JEP 286). It instructs the compiler to infer the type of a local variable from its initialiser. The inferred type is fixed at compile time — var does not make Java dynamically typed. // Before var ArrayList<String> names = new ArrayList<String>(); Map<String, List<Integer>> scores = new HashMap<String, List<Integer>>(); // With var var names = new ArrayList<String>(); var scores = new HashMap<String, List<Integer>>(); After compilation, both forms produce identical bytecode.