# Package org.springframework.util

Miscellaneous utility classes, such as String manipulation utilities, a Log4J configurer, and a state holder for paged lists of objects.

See: Description

- Interface Summary
  Interface | Description
  --- | ---
  AutoPopulatingList.ElementFactory<E> | Factory interface for creating elements for an index-based access data structure such as a `List`.
  ConcurrentReferenceHashMap.Reference<K,V> | A reference to an `ConcurrentReferenceHashMap.Entry` contained in the map.
  ErrorHandler | A strategy for handling errors.
  IdGenerator | Contract for generating `UUID` identifiers.
  MultiValueMap<K,V> | Extension of the `Map` interface that stores multiple values.
  PathMatcher | Strategy interface for `String`-based path matching.
  PropertiesPersister | Strategy interface for persisting `java.util.Properties`, allowing for pluggable parsing strategies.
  PropertyPlaceholderHelper.PlaceholderResolver | Strategy interface used to resolve replacement values for placeholders contained in Strings.
  ReflectionUtils.FieldCallback | Callback interface invoked on each field in the hierarchy.
  ReflectionUtils.FieldFilter | Callback optionally used to filter fields to be operated on by a field callback.
  ReflectionUtils.MethodCallback | Action to take on each method.
  ReflectionUtils.MethodFilter | Callback optionally used to filter methods to be operated on by a method callback.
  StringValueResolver | Simple strategy interface for resolving a String value.
  WeakReferenceMonitor.ReleaseListener | Listener that is notified when the handle is being released.

- Class Summary
  Class | Description
  --- | ---
  AlternativeJdkIdGenerator | A variation of `UUID.randomUUID()` that uses `SecureRandom` only for the initial seed and `Random` thereafter.
  AntPathMatcher | PathMatcher implementation for Ant-style path patterns.
  AntPathMatcher.AntPathStringMatcher | Tests whether or not a string matches against a pattern via a `Pattern`.
  AntPathMatcher.AntPatternComparator | The default `Comparator` implementation returned by `AntPathMatcher.getPatternComparator(String)`.
  Assert | Assertion utility class that assists in validating arguments.
  AutoPopulatingList<E> | Simple `List` wrapper class that allows for elements to be automatically populated as they are requested.
  ClassUtils | Miscellaneous class utility methods.
  CollectionUtils | Miscellaneous collection utility methods.
  CommonsLogWriter | `java.io.Writer` adapter for a Commons Logging `Log`.
  CompositeIterator<E> | Iterator that combines multiple other iterators.
  ConcurrencyThrottleSupport | Support class for throttling concurrent access to a specific resource.
  ConcurrentReferenceHashMap<K,V> | A `ConcurrentHashMap` that uses `soft` or weak references for both `keys` and `values`.
  ConcurrentReferenceHashMap.Entry<K,V> | A single map entry.
  CustomizableThreadCreator | Simple customizable helper class for creating new `Thread` instances.
  DefaultPropertiesPersister | Default implementation of the `PropertiesPersister` interface.
  DigestUtils | Miscellaneous methods for calculating digests.
  FileCopyUtils | Simple utility methods for file and stream copying.
  FileSystemUtils | Utility methods for working with the file system.
  LinkedCaseInsensitiveMap<V> | `LinkedHashMap` variant that stores String keys in a case-insensitive manner, for example for key-based access in a results table.
  LinkedMultiValueMap<K,V> | Simple implementation of `MultiValueMap` that wraps a `LinkedHashMap`, storing multiple values in a `LinkedList`.
  Log4jConfigurer | Convenience class that features simple methods for custom log4j configuration.
  MethodInvoker | Helper class that allows for specifying a method to invoke in a declarative fashion, be it static or non-static.
  MimeType | Represents a MIME Type, as originally defined in RFC 2046 and subsequently used in other Internet protocols including HTTP.
  MimeType.SpecificityComparator<T extends MimeType> |
  MimeTypeUtils | Miscellaneous `MimeType` utility methods.
  NumberUtils | Miscellaneous utility methods for number conversion and parsing.
  ObjectUtils | Miscellaneous object utility methods.
  PatternMatchUtils | Utility methods for simple pattern matching, in particular for Spring's typical "xxx*", "*xxx" and "*xxx*" pattern styles.
  PropertyPlaceholderHelper | Utility class for working with Strings that have placeholder values in them.
  ReflectionUtils | Simple utility class for working with the reflection API and handling reflection exceptions.
  ResizableByteArrayOutputStream | An extension of `ByteArrayOutputStream` that: has public `ResizableByteArrayOutputStream.grow(int)` and `ResizableByteArrayOutputStream.resize(int)` methods to get more control over the the size of the internal buffer has a higher initial capacity (256) by default
  ResourceUtils | Utility methods for resolving resource locations to files in the file system.
  SerializationUtils | Static utilities for serialization and deserialization.
  SocketUtils | Simple utility methods for working with network sockets — for example, for finding available ports on `localhost`.
  StopWatch | Simple stop watch, allowing for timing of a number of tasks, exposing total running time and running time for each named task.
  StopWatch.TaskInfo | Inner class to hold data about one task executed within the stop watch.
  StreamUtils | Simple utility methods for dealing with streams.
  StringUtils | Miscellaneous `String` utility methods.
  SystemPropertyUtils | Helper class for resolving placeholders in texts.
  TypeUtils | Utility to work with Java 5 generic type parameters.
  WeakReferenceMonitor | Track references to arbitrary objects using proxy and weak references.

- Enum Summary
  Enum | Description
  --- | ---
  ConcurrentReferenceHashMap.ReferenceType | Various reference types supported by this map.
  ConcurrentReferenceHashMap.Restructure | The types of restructuring that can be performed.

- Exception Summary
  Exception | Description
  --- | ---
  AutoPopulatingList.ElementInstantiationException | Exception to be thrown from ElementFactory.
  InvalidMimeTypeException | Exception thrown from `MimeTypeUtils.parseMimeType(String)` in case of encountering an invalid content type specification String.

## Package org.springframework.util Description

Miscellaneous utility classes, such as String manipulation utilities, a Log4J configurer, and a state holder for paged lists of objects.