# android.support.v4.util added in[version 22.1.0](https://developer.android.com/topic/libraries/support-library/revisions) # android.support.v4.util | This package is part of the Android[support library](https://developer.android.com/topic/libraries/support-library)which is no longer maintained. The support library has been superseded by[AndroidX](https://developer.android.com/jetpack/androidx)which is part of[Jetpack](https://developer.android.com/jetpack). We recommend using the AndroidX libraries in all new projects. You should also consider[migrating](https://developer.android.com/jetpack/androidx/migrate)existing projects to AndroidX. To find the AndroidX class that maps to this deprecated class, see the AndroidX support library[class mappings](https://developer.android.com/jetpack/androidx/migrate/class-mappings). ## Interfaces |-----------------------------------------------------------------------------------------------|-------------------------------------------| | [Pools.Pool](https://developer.android.com/reference/android/support/v4/util/Pools.Pool)\ | Interface for managing a pool of objects. | ## Classes |-----------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [ArrayMap](https://developer.android.com/reference/android/support/v4/util/ArrayMap)\ | ArrayMap is a generic key-\>value mapping data structure that is designed to be more memory efficient than a traditional[HashMap](https://developer.android.com/reference/java/util/HashMap), this implementation is a version of the platform's`android.util.ArrayMap`that can be used on older versions of the platform. | | [ArraySet](https://developer.android.com/reference/android/support/v4/util/ArraySet)\ | ArraySet is a generic set data structure that is designed to be more memory efficient than a traditional[HashSet](https://developer.android.com/reference/java/util/HashSet). | | [AtomicFile](https://developer.android.com/reference/android/support/v4/util/AtomicFile) | Static library support version of the framework's[AtomicFile](https://developer.android.com/reference/android/util/AtomicFile.html), a helper class for performing atomic operations on a file by creating a backup file until a write has successfully completed. | | [CircularArray](https://developer.android.com/reference/android/support/v4/util/CircularArray)\ | CircularArray is a generic circular array data structure that provides O(1) random read, O(1) prepend and O(1) append. | | [CircularIntArray](https://developer.android.com/reference/android/support/v4/util/CircularIntArray) | CircularIntArray is a circular integer array data structure that provides O(1) random read, O(1) prepend and O(1) append. | | [LongSparseArray](https://developer.android.com/reference/android/support/v4/util/LongSparseArray)\ | SparseArray mapping longs to Objects, a version of the platform's`android.util.LongSparseArray`that can be used on older versions of the platform. | | [LruCache](https://developer.android.com/reference/android/support/v4/util/LruCache)\ | Static library version of`android.util.LruCache`. | | [ObjectsCompat](https://developer.android.com/reference/android/support/v4/util/ObjectsCompat) | This class consists of static utility methods for operating on objects. | | [Pair](https://developer.android.com/reference/android/support/v4/util/Pair)\ | Container to ease passing around a tuple of two objects. | | [PatternsCompat](https://developer.android.com/reference/android/support/v4/util/PatternsCompat) | Commonly used regular expression patterns. | | [Pools](https://developer.android.com/reference/android/support/v4/util/Pools) | Helper class for creating pools of objects. | | [Pools.SimplePool](https://developer.android.com/reference/android/support/v4/util/Pools.SimplePool)\ | Simple (non-synchronized) pool of objects. | | [Pools.SynchronizedPool](https://developer.android.com/reference/android/support/v4/util/Pools.SynchronizedPool)\ | Synchronized) pool of objects. | | [SimpleArrayMap](https://developer.android.com/reference/android/support/v4/util/SimpleArrayMap)\ | Base implementation of[ArrayMap](https://developer.android.com/reference/android/support/v4/util/ArrayMap)that doesn't include any standard Java container API interoperability. | | [SparseArrayCompat](https://developer.android.com/reference/android/support/v4/util/SparseArrayCompat)\ | SparseArrays map integers to Objects. | - ## Interfaces - [Pools.Pool](https://developer.android.com/reference/android/support/v4/util/Pools.Pool) - ## Classes - [ArrayMap](https://developer.android.com/reference/android/support/v4/util/ArrayMap) - [ArraySet](https://developer.android.com/reference/android/support/v4/util/ArraySet) - [AtomicFile](https://developer.android.com/reference/android/support/v4/util/AtomicFile) - [CircularArray](https://developer.android.com/reference/android/support/v4/util/CircularArray) - [CircularIntArray](https://developer.android.com/reference/android/support/v4/util/CircularIntArray) - [LongSparseArray](https://developer.android.com/reference/android/support/v4/util/LongSparseArray) - [LruCache](https://developer.android.com/reference/android/support/v4/util/LruCache) - [ObjectsCompat](https://developer.android.com/reference/android/support/v4/util/ObjectsCompat) - [Pair](https://developer.android.com/reference/android/support/v4/util/Pair) - [PatternsCompat](https://developer.android.com/reference/android/support/v4/util/PatternsCompat) - [Pools](https://developer.android.com/reference/android/support/v4/util/Pools) - [Pools.SimplePool](https://developer.android.com/reference/android/support/v4/util/Pools.SimplePool) - [Pools.SynchronizedPool](https://developer.android.com/reference/android/support/v4/util/Pools.SynchronizedPool) - [SimpleArrayMap](https://developer.android.com/reference/android/support/v4/util/SimpleArrayMap) - [SparseArrayCompat](https://developer.android.com/reference/android/support/v4/util/SparseArrayCompat)