org.apache.commons.collections.set

This package contains implementations of the {@link java.util.Set Set} and {@link java.util.SortedSet SortedSet} interfaces.

The implementations are in the form of direct implementations and decorators. A decorator wraps another implementation of the interface to add some specific additional functionality.

The following implementations are provided in the package:

• CompositeSet - a set that combines multiple sets into one

• Synchronized - synchronizes method access for multi-threaded environments
• Unmodifiable - ensures the collection cannot be altered
• Predicated - ensures that only elements that are valid according to a predicate can be added
• Typed - ensures that only elements that are of a specific type can be added
• Transformed - transforms each element added
• ListOrdered - ensures that insertion order is retained
• MapBackedSet - a set formed by decorating a Map

Since Set doesn't stipulate much new behavior that isn't already found in Collection , this class basically just adds tests for Set.equals and Set.hashCode along with an updated AbstractTestSet.verify() that ensures elements do not appear more than once in the set.

To use, subclass and override the AbstractTestSet.makeEmptySet() method.

To use, subclass and override the AbstractTestSortedSet.makeEmptySet() method.

If an object is added to the set for a second time, it will remain in the original position in the iteration. The order can be observed from the set via the iterator or toArray methods.

The ListOrderedSet also has various useful direct methods.

This class is used to create a Set with the same properties as the key set of any map.

The validation of additions is performed via an instanceof test against a specified Class.

The validation of additions is performed via an instanceof test against a specified Class.