Last updated on 2020/09/29 to include changes up to JDK 15.

Since the release of version 8, up to version 15, Java is shaped by 163 JDK Enhancement Proposals (JEPs), each of which brings some improvement to the platform. This page is a categorized and curated list of the most important improvements.

Contents of this page:

• New Language Features
• New APIs
• Performance Improvements
• Security Improvements
• Bytecode Changes
• Launching
• Packaging
• Javadoc
• New Platforms
• Deprecation and Removal
• New Version Scheme

The full list of JEPs can be found on the OpenJDK website under the jdk and jdk9 projects.

All features are generally available and enabled by default, except if they are labelled with one of the following:

• Preview 🔍 features are fully specified and implemented, but not yet considered to be final. They are considered to be almost complete, waiting for an additional round of real-world feedback. They have to be explicitly enabled.
• Experimental 💥 features are less stable, and more likely to change. They also have to be explicitly enabled.
• Incubator 🥚 modules are non-final tools and API’s, and are distributed in separate modules.

New Language Features

When Java 8 introduced lambdas it was a pretty huge change. While recent versions did not add such impactful features, lots of smaller improvements were made to the language.

Here’s a quick recap on what happened in the last years. For a more in-depth guide, see New language features since Java 8.

• Text Blocks
  JDK 15 (Preview in JDK 14 JDK 13)

  String html = """
              
                  
                      
  Hello, world
                  
              
              """;
  

• Sealed Classes can restrict which other classes may extend them (Preview 🔍)
  JDK 15

  public abstract sealed class Shape
      permits Circle, Rectangle {...}
  
  public class Circle extends Shape {...} // OK
  public class Rectangle extends Shape {...} // OK
  public class Triangle extends Shape {...} // Compile error
  
  // No need for default case if all permitted types are covered
  double area = switch (shape) {
      case Circle c    -> Math.pow(c.radius(), 2) * Math.PI
      case Rectangle r -> r.a() * r.b()
  };
  

• Records (Preview 🔍)
  JDK 15 JDK 14

  record Point(int x, int y) { }
  

• Pattern Matching for instanceof (Preview 🔍)
  JDK 15 JDK 14

  if (obj instanceof String s) {
      System.out.println("obj is a String and it' length is " + s.length());
  }
  

• Switch Expressions
  JDK 14 (Preview in JDK 12 JDK 13)

  int numLetters = switch (day) {
      case MONDAY, FRIDAY, SUNDAY -> 6;
      case TUESDAY                -> 7;
      default      -> {
        String s = day.toString();
        int result = s.length();
        yield result;
      }
  };
  

• Helpful NullPointerExceptions describing precisely which variable was null
  JDK 14 (enabled with -XX:+ShowCodeDetailsInExceptionMessages)

  a.b.c.i = 99;
  ---
  Exception in thread "main" java.lang.NullPointerException:
        Cannot read field "c" because "a.b" is null
  

• Introduction of var to make local variable declarations less ceremonious
  JDK 11 (Without lambda support in JDK 10)

  var greeting = "Hello World!";
  

• Opt-in and backwards-compatible Module System to avoid ClassDefNotFoundErrors at runtime and create internal APIs
  JDK 9 (Project Jigsaw)

  module hu.advancedweb.helloworld {
      requires hu.advancedweb.somedependency;
      exports hu.advancedweb.hello
  }
  

• Private methods in interfaces
  JDK 9 (Milling Project Coin)

• Diamond operator for anonymous inner classes
  JDK 9 (Milling Project Coin)

• Try-with-resources allows effectively final variables
  JDK 9 (Milling Project Coin)

• @SafeVargs on private instance methods
  JDK 9 (Milling Project Coin)

• No deprecation warnings on import statements
  JDK 9

New APIs

Let’s continue with the Java Standard Library, focusing on the new features that we can use in day-to-day coding.

If you are curious about all the API level differences between Java 8 and 14, check the AdoptOpenJDK/jdk-api-diff on GitHub.

General

• Support Non-Volatile Mapped Byte Buffers in the FileChannel API
  JDK 14

• Files.mismatch: find the first mismatched byte in the content of two files
  JDK 12

• Collectors.teeing to create a Collector that is a composite of two downstream collectors
  JDK 12

• String enhancements: indent and transform
  JDK 12

• Standard HTTP Client featuring HTTP/2, WebSocket support and non-blocking API
  JDK 11 (Incubator 🥚 in JDK 9)

  HttpClient httpClient = HttpClient.newBuilder().build();
  
  HttpRequest request =
    HttpRequest.newBuilder()
      .uri(URI.create("https://advancedweb.hu/"))
      .GET()
      .build();
  
  HttpResponseString> response =
    httpClient.send(request, BodyHandlers.ofString());
  

• String enhancements, like isBlank, lines, repeat and strip
  JDK 11

• Convenience Factory Methods for Collections to ease the pain of not having collection literals
  JDK 9

  SetInteger> mySet = Set.of(1, 2, 3);
  ListInteger> myList = List.of(1, 2, 3);
  MapString, Integer> myMap = Map.of("one", 1, "two", 2);
  

• Reactive Streams publish-subscribe framework for asynchronous stream processing with non-blocking backpressure
  JDK 9

• Time-based enhancements to CompletableFuture (timeout, delay)
  JDK 9

• More options to transform (dropWhile, takeWhile) and generate (iterate, ofNullable) streams; readonly collectors (toUnmodifiableList); optionals can be transformed to streams
  JDK 9

• Arrays.mismatch: find the first mismatching element between two arrays
  JDK 9

• Stack-Walking API that allows laziness and stack-frame filtering
  JDK 9

• Process API provides more info and control (e.g. process ID, arguments, CPU time, parent/child processes), enhance ProcessBuilder to aid the creation of process pipelines
  JDK 9

• VarHandle API to replace the field and array related operations of java.util.concurrent.atomic and sun.misc.Unsafe in order to and provide low-level access mechamisms, e.g. atomic write.
  JDK 9

• New combinators and lookup methods for MethodHandle
  JDK 9

• Enhanced Deprecation policy. @Deprecated can be marked with forRemoval, which emits a new warning.
  JDK 9

• OASIS Standard XML Catalog API to manage external resources in XMLs in a secure and performant manner
  JDK 9

• Update JDK’s XML parser, Xerces, to version 2.11.0
  JDK 9

• TIFF Support for Image I/O Framework
  JDK 9

Internationalization

• Unicode 10.0, adding roughly 27.000 characters, 10 blocks, and more than 30 scripts
  JDK 11 (Unicode 8.0 support in JDK 9)

• java.util.Locale and related APIs support currency type, time zone and more
  JDK 10

• ResourceBundle loads properties files in UTF-8 instead of ISO-8859-1
  JDK 9

• CLDR Locale Data Enabled by Default
  JDK 9

Graphics and Desktop Applications

• Desktop features for all platforms like login/logout/lock event listener and task bar interactions
  JDK 9

• MultiResolutionImage that makes easy to retrieve a resolution-specific image for a DPI
  JDK 9

• HiDPI Graphics on Windows and Linux
  JDK 9

• Enable GTK 3 on Linux for JavaFX, Swing, and AWT
  JDK 9

• Replace @beaninfo Javadoc tags with @BeanInfo annotations for Swing
  JDK 9

• Update GStreamer included in JavaFX/Media to version 1.4.4
  JDK 9

• Replace the existing ICU OpenType font-layout engine with HarfBuzz
  JDK 9

Performance Improvements

General

• Foreign-Memory Access API to safely and efficiently use off-heap memory (Incubator 🥚)
  JDK 15 JDK 14

• Enable dynamic archiving of classes at the end of Java application execution
  JDK 13

• Application Class-Data Sharing to improve startup time and reduce footprint by sharing class metadata between Java processes.
  JDK 10

• Class-Data Sharing archive of the default class list is enabled by default to improve out-of-the-box startup time
  JDK 12

• Space-efficient, Compact Strings that stores Latin-1 only Strings more efficiently
  JDK 9

• Code caches of profiled and non-profiled compiled code is separated, resulting in improved performance and memory footprint
  JDK 9

• Store Interned Strings in Class-Data Sharing archives to reduce memory consumption
  JDK 9

Library

• Improved intrinsics for java.lang.Math sin, cos and log functions on AArch64 processors
  JDK 11

• Security Manager performance improvements
  JDK 9

• Spin-Wait Hint (Thread#onSpinWait) to optimize busy-waiting style loops
  JDK 9

• Use Marlin Renderer in Java 2D as the default graphics rasterizer instead of Pisces
  JDK 9

• Improved GHASH and RSA performance by leveraging recently-introduced SPARC and Intel x64 CPU instructions
  JDK 9

Concurrency

• Thread-Local Handshakes to stop individual threads
  JDK 10

• Improved performance of contended object monitors
  JDK 9

• Extra space on thread stack for critical sections, mitigating the risk of a deadlock in java.util.concurrent locks in case of a stack overflow
  JDK 9

Compiler

• Ahead-of-Time Compilation capability for Linux (Experimental 💥)
  JDK 10 (Graal as an experimental JIT Compiler) JDK 9 (JVM Compiler Interface) JDK 9 (Graal as an AoT Compiler)

• Performance improvement in javac: new strategy for type checking poly expressions
  JDK 9

G1 Garbage Collector (default)

• NUMA-Aware Memory Allocation
  JDK 14

• Abortable mixed collections to meet user-supplied pause goals
  JDK 12

• Automatically return heap memory to the operating system when idle
  JDK 12

• Parallel Full GC to improve worst-case latencies
  JDK 10

• G1 Garbage Collector is now the default instead of Parallel GC
  JDK 9

Other Garbage Collectors

• Z Garbage Collector, offering very low pause times on large heaps
  JDK 15 (Experimental 💥 in JDK 14 (Windows) JDK 14 (OS X) JDK 11 (Linux) )

• Shenandoah Garbage Collector, offering similar benefits as ZGC but based on a different algorithm
  JDK 15 (Experimental 💥 in JDK 12 )

• Epsilon Garbage Collector, which does not implement actual memory reclamation, striving for the lowest overhead possible
  JDK 11

• XX:AllocateHeapAt= to support Alternative Memory Devices
  JDK 10

Diagnostic and Tools

• Flight Recorder Event Streaming: profiling data is available via an API, making it suitable for continuous monitoring
  JDK 14

• Microbenchmark Suite based on JMH
  JDK 12

• Flight Recorder is part of OpenJDK
  JDK 11

• Low-Overhead Heap Profiling via JMTI
  JDK 11

• Run-time manageable and method specific control of the C1 and C2 compilers that enables contained tests
  JDK 9

• Fine-grained, easy-to-configure Logging System for all components of the JVM
  JDK 9 (Unified JVM Logging) JDK 9 (Unified GC Logging)

• Allow the application to provide logger implementation to be used by platform classes
  JDK 9

Security Improvements

• Default set of root Certification Authority (CA) certificates are provided with the JDK, so TLS connections are working out of the box
  JDK 10

• Validate Incoming Serialization Data
  JDK 9

• Default keystore type is the standard PKCS12 instead of the proprietary JKS
  JDK 9

• DRBG-Based SecureRandom
  JDK 9

• Disable X.509 certificate chains with SHA-1 based signatures
  JDK 9

• SHA-3 Hash Algorithms
  JDK 9

TLS

• TLS 1.3 support
  JDK 11

• API for Datagram Transport Layer Security (DTLS)
  JDK 9

• OCSP stapling TLS to improve performance of certificate status checking
  JDK 9

• TLS Application-Layer Protocol Negotiation (ALPN) Extension which enables protocol negotiation without additional round trips; ALPN is a requirement for HTTP/2 connections
  JDK 9

Crypto

• Edwards-Curve Digital Signature Algorithm (EdDSA) - RFC8032
  JDK 15

• Key Agreement with Curve25519 and Curve448
  JDK 11

• ChaCha20 and Poly1305 Cryptographic Algorithms
  JDK 11

Launching

• Launch Single-File Source-Code Programs, including support for shebang (#!) line on Unix
  JDK 11

• jshell: the Java REPL
  JDK 9 (Project Kulla)
  → Related: Prototyping with JShell

• Compile for Older Platform Versions with --release, which configures --source and --target and links against the appropriate platform version
  JDK 9

• Early validatation of JVM Command-Line Flags to avoid crashes
  JDK 9

Packaging

• Packaging Tool supporting native package formats: msi, exe, pkg, dmg, deb and rpm (Incubator 🥚)
  JDK 14

• jlink Java Linker that can build an optimized, slim run-time image for a modular Java application thag contains only the required parts of the JDK
  JDK 9 - [2], [3], [4], [4], [5]

• Multi-Release JAR Files to allow multiple, Java-release-specific versions of class in a single archive
  JDK 9

Javadoc

• The Javadoc tool now emits HTML5 markup instead of a frame-based layout and the documentation contains a search box to ease navigation
  JDK 9 - [2], [3]

Bytecode

• Replace Unsafe::defineAnonymousClass() with Lookup::defineHiddenClass(), intended for frameworks to dynamically generate Hidden Classes that can’t be discovered, linked, and used directly by other classes. JDK 15

• java.lang.invoke.constant package to allow easy description of loadable constants (operands for the ldc instruction), which is less error-prone than relying on ad-hoc String representation
  JDK 12

• CONSTANT_Dynamic constant-pool entry which uses bootstrapping to perform the resolution, similarly to INVOKEDYNAMIC calls
  JDK 11

• Introduction of the Nest access-control context that wraps classes in the same code entity - such as nested classes - and eliminates the need for compiler to insert bridge methods to the generated bytecode.
  JDK 11

• Bytecode generated for static String-concatenation uses invokedynamic rather than directly creating StringBuilder#append chains. This will enable future optimizations of String concatenation without requiring bytecode changes.
  JDK 9

• INVOKEDYNAMIC can express high-level operations on object properties and or collections
  JDK 9

New supported platforms

• Linux/AArch64
  JDK 9

• Linux/s390x
  JDK 9

• Unified arm32/arm64
  JDK 9

New Version Scheme

• Simpler Version-String Scheme, aligned with Semantic Versioning.
  JDK 9 JDK 10

Deprecation and removal

• Remove the Nashorn Javascript Engine and the jjs tool
  JDK 15 (Deprecated in JDK 11)

• Remove the Solaris and SPARC Ports
  JDK 15 (Deprecated in JDK 14)

• Deprecate RMI Activation, affecting the java.rmi.activation package and the rmid tool, does not affect Java RMI in general
  JDK 15

• Disable Biased Locking by default, deprecate related command-line flags
  JDK 15

• Deprecate Unsafe::defineAnonymousClass()
  JDK 15

• Remove the Concurrent Mark Sweep (CMS) Garbage Collector
  JDK 14

• Deprecate the ParallelScavenge + SerialOld GC Combination
  JDK 14

• Remove the Pack200 Tools and API
  JDK 14

• Deprecate the Pack200 Tools and API
  JDK 11

• Remove Java EE
  JDK 11

• Remove CORBA
  JDK 11

• Remove Thread#destroy and Thread#stop
  JDK 11

• var is no longer a valid class name
  JDK 10

• Remove the javah tool
  JDK 10

• Underscore is no longer a valid identifier
  JDK 9

• Internal API’s (sun.*) are removed or deprecated
  JDK 9 - [2]

• Remove apple.applescript and com.apple packages
  JDK 9

• Disable X.509 certificate chains with SHA-1 based signatures
  JDK 9

• Remove Launch-Time JRE Version Selection directives: JRE-Version manifest entry and -version: cli option
  JDK 9

• Remove the jhat tool
  JDK 9

• Remove the JVM TI hprof Agent
  JDK 9

• Remove GC Combinations Deprecated in JDK 8
  JDK 9

• ResourceBundle loads properties files in UTF-8 instead of ISO-8859-1
  JDK 9

• Deprecate Applet API
  JDK 9

• Deprecate the Concurrent Mark Sweep Garbage Collector
  JDK 9

• Deprecate Object.finalize()
  JDK 9

• Remove the Endorsed Standards Override (lib/endorsed) and Extensions (lib/ext) mechanisms from the JRE
  JDK 9

• Remove rt.jar from the JRE
  JDK 9

If you are curious about all the API level differences between Java 8 and 14, check the Java Almanac project. Also check out jdeps, the Java class dependency analyzer to find out if your project is still using an old internal API.

Summary

JDK 8 was released in 2014. We had to wait for three and a half years for JDK 9. But since then things accelerated. Java has a new release structure that aims to deliver a new version in every six months.

While Java 8 is still supported, migrating to the latest version brings considerable amount of improvements to the table.