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Java Collections Libraries

Overview

Java Collections Framework

Name Description
ArrayList An indexed sequence that grows and shrinks dynamically
LinkedList An ordered sequence that allows efficient insertions and removal at any location
ArrayDeque A double-ended queue that is implemented as a circular array
HashSet An unordered collection that rejects duplicates
TreeSet A sorted set
EnumSet A set of enumerated type values
LinkedHashSet A set that remembers the order in which elements were inserted
PriorityQueue A collection that allows efficient removal of the smallest element
HashMap A data structure that stores key/value associations
TreeMap A map in which the keys are sorted
EnumMap A map in which the keys belong to an enumerated type
LinkedHashMap A map that remembers the order in which entries were added
WeakHashMap A map with values that can be reclaimed by the garbage collector if they are not used elsewhere
IdentityHashMap A map with keys that are compared by ==, not equals

  1. Guava is a set of core Java libraries from Google that includes new collection types (such as multimap and multiset), immutable collections, a graph library, and utilities for concurrency, I/O, hashing, primitives, strings, and more! It is widely used on most Java projects within Google, and widely used by many other companies as well. ↩

  2. 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; it provides also big (64-bit) arrays, sets, and lists, sorting algorithms, fast, practical I/O classes for binary and text files, and facilities for memory mapping large files. ↩

  3. JCTools Java Concurrency Tools for the JVM. This project aims to offer some concurrent data structures currently missing from the JDK. ↩

  4. JGraphT is Java class library that provides mathematical graph-theory objects and algorithms. ↩

  5. JUNG is the Java Universal Network/Graph Framework. ↩

  6. vavr provides persistent collections, functional abstractions for error handling, concurrent programming, pattern matching and much more. ↩