# Package org.apache.commons.collections.set

This package contains implementations of the `Set` and `SortedSet` interfaces.

See: Description

- Interface Summary
  Interface | Description
  --- | ---
  CompositeSet.SetMutator | Define callbacks for mutation operations.

- Class Summary
  Class | Description
  --- | ---
  AbstractSerializableSetDecorator | Serializable subclass of AbstractSetDecorator.
  AbstractSetDecorator | Decorates another `Set` to provide additional behaviour.
  AbstractSortedSetDecorator | Decorates another `SortedSet` to provide additional behaviour.
  CompositeSet | Decorates a set of other sets to provide a single unified view.
  ListOrderedSet | Decorates another `Set` to ensure that the order of addition is retained and used by the iterator.
  MapBackedSet | Decorates a `Map` to obtain `Set` behaviour.
  PredicatedSet | Decorates another `Set` to validate that all additions match a specified predicate.
  PredicatedSortedSet | Decorates another `SortedSet` to validate that all additions match a specified predicate.
  SynchronizedSet | Decorates another `Set` to synchronize its behaviour for a multi-threaded environment.
  SynchronizedSortedSet | Decorates another `SortedSet` to synchronize its behaviour for a multi-threaded environment.
  TransformedSet | Decorates another `Set` to transform objects that are added.
  TransformedSortedSet | Decorates another `SortedSet` to transform objects that are added.
  TypedSet | Decorates another `Set` to validate that elements added are of a specific type.
  TypedSortedSet | Decorates another `SortedSet` to validate that elements added are of a specific type.
  UnmodifiableSet | Decorates another `Set` to ensure it can't be altered.
  UnmodifiableSortedSet | Decorates another `SortedSet` to ensure it can't be altered.

## Package org.apache.commons.collections.set Description

This package contains implementations of the `Set` and `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

The following decorators are provided in the package:

- 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

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