More than Persistent Collections ❤️

Contain persistent(immutable) collections/Functional Data Structures 📌

• vavr ❤️ , VΛVΓ (Vavr, formerly called Javaslang) is a non-commercial, non-profit object-functional library that runs with Java 8+. It aims to reduce the lines of code and increase code quality.
  • homepage: http://vavr.io/
    • documentation: http://docs.vavr.io/
  • code repo: https://github.com/vavr-io/vavr
  • has simple Kotlin integration 🍩: https://github.com/vavr-io/vavr-kotlin
• cyclops ❤️ , An advanced, but easy to use, platform for writing functional applications in Java 8.
  • homepage: http://cyclops-react.io/
  • code repo: https://github.com/aol/cyclops-react
  • excellent ecosystem integration, see the cyclops integration modules
    • related/similar lib integration: RxJava, Reactor, guava, vavr, functionaljava...
• Functional Java , Functional programming in Java
  • code repo: https://github.com/functionaljava/functionaljava
• procrastination , A small, straightforward library bringing the benefits of functional programming to Java 11
  • code repo: https://github.com/gdejohn/procrastination
• sophisticated FP Languages ❤️ have built-in Persistent Collections support 📌
  • Scala ❤️ , Scala combines object-oriented and functional programming in one concise, high-level language. Scala's static types help avoid bugs in complex applications, and its JVM and JavaScript runtimes let you build high-performance systems with easy access to huge ecosystems of libraries.
    • homepage: http://scala-lang.org/
    • code repo: https://github.com/scala/scala
  • Clojure ❤️ , Clojure is a dynamic, general-purpose programming language, combining the approachability and interactive development of a scripting language with an efficient and robust infrastructure for multithreaded programming. Clojure is a compiled language, yet remains completely dynamic – every feature supported by Clojure is supported at runtime. Clojure provides easy access to the Java frameworks, with optional type hints and type inference, to ensure that calls to Java can avoid reflection.
    • homepage: https://clojure.org
    • code repo: https://github.com/clojure/clojure

Persistent(immutable) Collections/Functional Data Structures 📌

• PCollections , A Persistent Java Collections Library
  • code repo: https://github.com/hrldcpr/pcollections
• Capsule , aims to become a full-fledged (immutable) collections library for Java 8+ that is solely built around persistent tries.
  • code repo: https://github.com/usethesource/capsule
• dexx , Dexx Collections are a port of Scala's immutable, persistent collection classes to pure Java.
  • code repo: https://github.com/andrewoma/dexx
  • has Kotlin integration 🍩
• Paguro , Type-safe versions of Clojure's immutable/persistent collections
  • code repo: https://github.com/GlenKPeterson/Paguro
• java-immutable-collections Efficient Immutable/Persistent Collections for Java
  • code repo: https://github.com/brianburton/java-immutable-collections
  • https://github.com/brianburton/java-immutable-collections/wiki/Comparative-Performance

Primitive Collections/Type-specific Collections 💎

• fastutil ❤️ , fastutil extends the Java™ Collections Framework by providing type-specific maps, sets, lists and queues with a small memory footprint and fast access and insertion; provides also big (64-bit) arrays, sets and lists, and fast, practical I/O classes for binary and text files.
  • homepage: http://fastutil.di.unimi.it/
  • code repo: https://github.com/vigna/fastutil
• eclipse-collections , Eclipse Collections is a collections framework for Java with optimized data structures and a rich, functional and fluent API.
  • eclipse-collections is more than a primitive collection lib
  • code repo: https://github.com/eclipse/eclipse-collections
  • home page: https://www.eclipse.org/collections/
• trove4j , High performance collections for Java
  • code repo: https://bitbucket.org/trove4j/trove/src/master/
• hppc , HPPC provides template-generated implementations of typical collections, such as lists, sets and maps, for all Java primitive types. The primary driving force behind HPPC is optimization for highest performance and memory efficiency.
  • homepage: http://labs.carrotsearch.com/hppc.html
  • code repo: https://github.com/carrotsearch/hppc

High Performance/Sophisticated Collection(-ish) 🚄

• JCTools ❤️ , offer some concurrent data structures currently missing from the JDK. JCTools offers excellent performance. It's stable and in use by such distinguished frameworks as Netty, RxJava and others.
  • code repo: https://github.com/JCTools/JCTools
• disruptor ❤️ , A High Performance Inter-Thread Messaging Library. Achieve very low-latency and high-throughput with our Java platform. Performance testing showed that using queues to pass data between stages of the system was introducing latency, so we focused on optimising this area.
  • home page: http://lmax-exchange.github.io/disruptor/
  • code repo: https://github.com/LMAX-Exchange/disruptor
• High Scale Lib ❤️ , Cliff Click's high scale lib.
  • code repo: https://github.com/boundary/high-scale-lib
• caffeine ❤️ , Caffeine is a high performance, near optimal caching library based on Java 8. For more details, see our user's guide and browse the API docs for the latest release.
  • Caffeine is the Java 8 successor to ConcurrentLinkedHashMap and Guava's cache. Projects should prefer Caffeine and migrate when requiring JDK8 or higher. The previous caching projects are supported in maintenance mode.
  • code repo: https://github.com/ben-manes/caffeine
  • home page: https://commons.apache.org/proper/commons-collections/
• concurrentlinkedhashmap , A high performance version of java.util.LinkedHashMap for use as a software cache.
  • Caffeine is the Java 8 successor to ConcurrentLinkedHashMap and Guava's cache. Projects should prefer Caffeine and migrate when requiring JDK8 or higher. The previous caching projects are supported in maintenance mode.
  • code repo: https://github.com/ben-manes/concurrentlinkedhashmap

Collections Backed by Storage 🗃

• mapdb ❤️ , MapDB provides Java Maps, Sets, Lists, Queues and other collections backed by off-heap or on-disk storage. It is a hybrid between java collection framework and embedded database engine.
  • code repo: https://github.com/jankotek/mapdb
  • home page: http://www.mapdb.org/

Collections with Distribution 🌏

• Chronicle Map ❤️ , Chronicle Map is a super-fast, in-memory, non-blocking, key-value store, designed for low-latency, and/or multi-process applications such as trading and financial market applications.
  • home page: http://chronicle.software/products/chronicle-map/
    • Replicate your Key Value Store across your network, with consistency, persistance and performance.
  • code repo: https://github.com/OpenHFT/Chronicle-Map
• Chronicle Queue ❤️ , Chronicle Queue is a Java project focused on building a persisted low-latency messaging framework for high performance and critical applications.
  • home page: http://chronicle.software/products/chronicle-queue/
    • Store complete history of all your messages to disk. With Chronicle Queue you are able to persist every single event and message, It records each event to a memory mapped file.
  • code repo: https://github.com/OpenHFT/Chronicle-Queue

Contain Collections, but NOT Persistent 😱

• eclipse-collections , Eclipse Collections is a collections framework for Java with optimized data structures and a rich, functional and fluent API.
  • code repo: https://github.com/eclipse/eclipse-collections
  • home page: https://www.eclipse.org/collections/
  • NOT persistent collections! 😱 not nice!
    • implementation of java collections, has update operations actually and update operations throw UnsupportedOperationException 😱, not nice!
• commons-collections4 , The Apache Commons Collections package contains types that extend and augment the Java Collections Framework.
  • code repo: https://github.com/apache/commons-collections
  • home page: https://commons.apache.org/proper/commons-collections/
• guava
  • it is well known that guava is more than a collection lib
  • Caffeine is the Java 8 successor to ConcurrentLinkedHashMap and Guava's cache. Projects should prefer Caffeine and migrate when requiring JDK8 or higher. The previous caching projects are supported in maintenance mode.
  • code repo: https://github.com/google/guava
  • contains immutable collections
    • https://github.com/google/guava/wiki/ImmutableCollectionsExplained
    • NOT persistent collections! 😱 not nice!
      • implementation of java collections, has update operations actually and update operations throw UnsupportedOperationException 😱, not nice!

Related Resources

Maven Repository: collections https://mvnrepository.com/tags/collections

• persistent (immutable) collections
  • Faster Purely Functional Data Structures for Java
  • Data Structures in a Nutshell - vavr.io/vavr-docs
    Functional Data Structures = immutable + persistent
  • Immutable/Persistent Data Structures for Functional JS – Anjana Vakil – PartialConf 2017 - Youtube
    Terrific share for Persistent Data Structures!! ❤️
• primitive collections
  • Fastutil vs. Trove4j
    https://greatpowerlaw.wordpress.com/2013/04/08/fastutil-vs-trove4j/
  • Trove library: using primitive collections for performance
    http://java-performance.info/primitive-types-collections-trove-library/
  • Efficient Scala with Primitive Collections
    https://blog.juma.me.uk/tag/primitive-collections/
  • Memory usage of Java objects: general guide
    https://www.javamex.com/tutorials/memory/object_memory_usage.shtml