Eclipse Collections is a library of collection-management utilities that work with the Java Collections Framework (JCF). It offers JCF-compatible implementation alternatives for List, Set and Map. It also introduces a host of new features including Multimaps, BiMaps and Bags, lazy evaluation, immutable containers, parallel processing and a full complement of primitive containers.
A collections framework for Java based on Smalltalk patterns.
Eclipse Collections is based on the concept of internal iteration—putting collection-handling methods on the collection classes, a concept derived from the Smalltalk language. Internal iteration affords a more consistent and intuitive approach to managing collections by encapsulating the details of how various iteration patterns are implemented. Hiding this complexity lets you write more readable code with less duplication.
This guide is an introduction to basic Eclipse Collections concepts and its commonly-used features. It provides a high-level survey of the Eclipse Collections library and its capabilities. The topics covered are:
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Iteration Patterns: the logic underlying Eclipse Collections methods.
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Collections and Containers: the JCF-compatible collection types and new containers introduced in Eclipse Collections.
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Code Blocks: functions that can be passed as parameters, plus factory classes, static methods, and other features of the library.
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Testing Utilities: a specialized implementation of the JUnit Assert class for Eclipse Collections unit testing.
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Quick Reference: a topical "cheat sheet" with links to the Eclipse Collections API documentation.
We recommend first-time users try out the Eclipse Collections Kata. The Kata is a fun way to help you learn idiomatic Eclipse Collections usage through coding exercises.