Client and backend. Every class listed here is shared: the same code is compiled into your app and into your server. The package's page in the client API lists all of it, including any classes that exist only in the app.

package java.util

Types

class AbstractCollectionClass AbstractCollection is an abstract implementation of the Collection interface.
class AbstractListAbstractList is an abstract implementation of the List interface, optimized for a backing store which supports random access.
class AbstractMapThis class is an abstract implementation of the Map interface.
class AbstractQueueAbstractQueue is an abstract class which implements some of the methods in Queue.
class AbstractSequentialListAbstractSequentialList is an abstract implementation of the List interface.
class AbstractSetAn AbstractSet is an abstract implementation of the Set interface.
class ArrayDequeAn implementation of Deque, backed by an array.
class ArrayListArrayList is an implementation of List, backed by an array.
class ArraysArrays contains static methods which operate on arrays.
class Base64java.util.Base64: the basic, URL-safe and MIME encodings of RFC 4648 and RFC 2045, by the JDK’s rules for padding and for what a decoder refuses.
class BitSetThe BitSet class implements a bit field.
class CalendarCalendar is an abstract base class for converting between a Date object and a set of integer fields such as YEAR, MONTH, DAY, HOUR, and so on.
interface CollectionCollection is the root of the collection hierarchy.
class CollectionsCollections contains static methods which operate on Collection classes.
interface ComparatorA Comparator is used to compare two objects to determine their ordering with respect to each other.
class ConcurrentModificationExceptionAn ConcurrentModificationException is thrown when a Collection is modified and an existing iterator on the Collection is used to modify the Collection as well.
class DateThe class Date represents a specific instant in time, with millisecond precision.
interface DequeA kind of collection that can insert or remove element at both ends(“double ended queue”).
class DictionaryNote: Do not use this class since it is obsolete. Please use the Map interface for new implementations.
class DoubleSummaryStatisticsThe count, sum, minimum, maximum and average of the values it was given.
class EmptyStackExceptionThrown by methods in the Stack class to indicate that the stack is empty.
interface EnumerationAn object that implements the Enumeration interface generates a series of elements, one at a time.
interface EventListenerEventListener is the superclass of all event listener interfaces.
class EventListenerProxyThis abstract class provides a simple wrapper for objects of type EventListener.
class EventObjectjava.util.EventObject: the root of every listener event, carrying the object the event happened on.
class HashMapHashMap is an implementation of Map.
class HashSetHashSet is an implementation of a Set.
class HashtableHashtable associates keys with values.
class HexFormatjava.util.HexFormat: bytes to hexadecimal text and back, with an optional delimiter between bytes and a prefix and suffix around each.
class IdentityHashMapIdentityHashMap is a variant on HashMap which tests equality by reference instead of equality by value.
class IntSummaryStatisticsThe count, sum, minimum, maximum and average of the values it was given.
interface IteratorAn Iterator is used to sequence over a collection of objects.
class LinkedHashMapLinkedHashMap is a variant of HashMap.
class LinkedHashSetLinkedHashSet is a variant of HashSet.
class LinkedListLinkedList is an implementation of List, backed by a linked list.
interface ListA List is a collection which maintains an ordering for its elements.
interface ListIteratorAn ListIterator is used to sequence over a List of objects.
class LocaleA language, a country and a variant, with the JDK’s value semantics: two locales of the same codes are equal, hash alike and print alike (en_US).
class LongSummaryStatisticsThe count, sum, minimum, maximum and average of the values it was given.
interface MapA Map is a data structure consisting of a set of keys and values in which each key is mapped to a single value.
class MissingResourceExceptionA resource bundle, or a key in one, could not be found.
interface NavigableMapNavigableMap is a SortedMap with navigation methods answering the closest matches for specified item.
interface NavigableSetNavigableSet is a SortedSet with navigation methods answering the closest matches for specified item.
class NoSuchElementExceptionThrown by the nextElement method of an Enumeration to indicate that there are no more elements in the enumeration.
class ObjectsThis is a compatibility class which supports the java.util.Objects API.
class ObservableObservable is used to notify a group of Observer objects when a change occurs.
interface ObserverObserver is the interface to be implemented by objects that receive notification of updates on an Observable object.
class OptionalA container that may or may not hold a non-null value (the Java 8 API).
class OptionalDoubleA container that holds one double or nothing.
class OptionalIntA container that holds one int or nothing.
class OptionalLongA container that holds one long or nothing.
interface PrimitiveIteratorAn iterator that can hand out its elements unboxed.
class PriorityQueueA PriorityQueue holds elements on a priority heap, which orders the elements according to their natural order or according to the comparator specified at construction time.
class PropertiesString keys and values, a second table of defaults behind them, and the .properties text format.
interface QueueThis kind of collection provides advanced operations compared to basic collections, such as insertion, extraction, and inspection.
class RandomAn instance of this class is used to generate a stream of pseudorandom numbers.
interface RandomAccessRandomAccess is implemented by List implementations that support fast (usually constant time) random access.
interface SetA Set is a data structure which does not allow duplicate elements.
interface SortedMapA map that has its keys ordered.
interface SortedSetSortedSet is a Set which iterates over its elements in a sorted order.
interface SpliteratorA source of elements that hands them out one at a time, which is what java.util.stream.StreamSupport makes a stream of.
class SpliteratorsWays to make a Spliterator of a collection or an iterator, and an iterator of a spliterator.
class StackStack is a Last-In/First-Out(LIFO) data structure which represents a stack of objects.
class StringJoinerjava.util.StringJoiner: builds a sequence of strings separated by a delimiter, optionally between a prefix and a suffix.
class StringTokenizerThe StringTokenizer class allows an application to break a string into tokens by performing code point comparison.
class TimeZoneTimeZone represents a time zone offset, and also figures out daylight savings.
class Timer
class TimerTask
class TreeMapTreeMap is an implementation of SortedMap.
class TreeSetTreeSet is an implementation of SortedSet.
class UUIDA 128 bit identifier: its canonical text form, random (version 4) generation and name based (version 3) generation.
class VectorVector is a variable size contiguous indexable array of objects.
class WeakHashMapjava.util.WeakHashMap: a map that does not keep its keys alive.