Java News from Sunday, June 13, 2004

Release early and release often. Even if Sun can't decide whether it's open sourcing Java or not, it's at least learning a few tricks from the open source community. They have begun posting nightly builds of Java 1.5, a.k.a Tiger (not to be confused with the next version of Mac OS X).

Speaking of release early and release often, expect a second alpha of XOM later this week. I've fixed a couple of bugs in various corners of the implementation, and will be posting alpha 2 just as soon as I get confirmation from the original reporters that my changes fix the bugs.

The Apache Jakarta Project has posted the first release candidate of Commons Collections 3.1, an open source library that extends and augments the Java Collections Framework. It includes:

• Bag interface for collections that have a number of copies of each object
• Buffer interface for collections that have a well defined removal order, like FIFOs
• BidiMap interface for maps that can be looked up from value to key as well and key to value
• MapIterator interface to provide simple and quick iteration over maps
• Type checking decorators to ensure that only instances of a certain type can be added
• Transforming decorators that alter each object as it is added to the collection
• Composite collections that make multiple collections look like one
• Ordered maps and sets that retain the order elements are added in, including an LRU based map
• Identity map that compares objects based on their identity (==) instead of the equals method
• Reference map that allows keys and/or values to be garbage collected under close control
• Many comparator implementations
• Many iterator implementations
• Adapter classes from array and enumerations to collections
• Utilities to test or create typical set-theory properties of collections such as union, intersection, and closure

Version 3.1 is mostly backwards compatible with 3.0. It adds a number of new classes including TreeList, MultiKeyMap, SingletonMap, ObjectGraphIterator, MapBackedSet, ReferenceIdentityMap, AbstractReferenceMap, EmptyIterator, TransformedPredicate, PredicateDecorator, and AbstractSerializableDecorator. A number of other classes are now Serializable, and various methods have been added to existing classes. And of course bugs have been fixed.