The Java Evolution of Eclipse Collections
Speaker: Kristen O’Leary
See the list of all blog posts from the conference

Eclipse Collections

• was once GS (Goldman Sachs) Collections
• Memory efficient collections framework
• Open sourced in 2012

Java 8

• 8.0 compatible with Java 8+
• Extend Java 8 Functional Interfaces
• New APIs – ex: reduceInPlace

Optional

• RichIteratable.detectWith() used to rutn null if no match
• Pre Java-8 could use detectIfNone() to create if doesn’t exist
• New method detectWithOptional() which returns Optional wrapper

Collectors

• Collectors2 has collectors
• Can collect into Bag, ImmutableSet, BiMap, Stack, etc
• Have full primitive collections library
• Have full set of multi-map (map with multiple values for same key ex: key to list/set)
• Have extra APIs like chunk() and zip()

Default methods

• RichIterable is common interface so default methods helpful.
• Used to add reduceInPlace() so don’t need to stream and create new collection
• Also useful for asLazy() or toImutabile() since Eclipse Collections doesn’t provide stream() there.

Primitive Collections

• Code generate the primitive classes so symmetry
• Showed impressive memry savings – Eclipse Collections and Trove equivalent. Much smaller than with autoboxing and faster too
• LazyIterable availalbe for all 8 primitive types. Just call asLazy(). A LazyIterabe can be reused unlike a stream.

Java 9

• Module system
• Internal API Encapsulation
• Need to change APIs that use reflection in order to build. Can’t call setAccessible(true) any more.
• There is a command line argument to ignore reflection errors. Don’t want to impose that on callers

I like that Kristen uses kata examples to show hw the APIs work.