java.util

Interfaces

Collection<E> The root interface in the collection hierarchy
Comparator<T> A comparison function, which imposes a total ordering on some collection of objects. 
Deque<E> A linear collection that supports element insertion and removal at both ends. 
Enumeration<E> An object that implements the Enumeration interface generates a series of elements, one at a time. 
EventListener A tagging interface that all event listener interfaces must extend. 
Formattable The Formattable interface must be implemented by any class that needs to perform custom formatting using the 's' conversion specifier of Formatter
Iterator<E> An iterator over a collection. 
List<E> An ordered collection (also known as a sequence). 
ListIterator<E> An iterator for lists that allows the programmer to traverse the list in either direction, modify the list during iteration, and obtain the iterator's current position in the list. 
Map<K, V> An object that maps keys to values. 
Map.Entry<K, V> A map entry (key-value pair). 
NavigableMap<K, V> A SortedMap extended with navigation methods returning the closest matches for given search targets. 
NavigableSet<E> A SortedSet extended with navigation methods reporting closest matches for given search targets. 
Observer A class can implement the Observer interface when it wants to be informed of changes in observable objects. 
PrimitiveIterator<T, T_CONS> A base type for primitive specializations of Iterator
PrimitiveIterator.OfDouble An Iterator specialized for double values. 
PrimitiveIterator.OfInt An Iterator specialized for int values. 
PrimitiveIterator.OfLong An Iterator specialized for long values. 
Properties.XmlLoader Creates a dynamic dependency on XML support so that XML support can be excluded from the application binary without incurring link errors. 
Queue<E> A collection designed for holding elements prior to processing. 
RandomAccess Marker interface used by List implementations to indicate that they support fast (generally constant time) random access. 
Set<E> A collection that contains no duplicate elements. 
SortedMap<K, V> A Map that further provides a total ordering on its keys. 
SortedSet<E> A Set that further provides a total ordering on its elements. 
Spliterator<T> An object for traversing and partitioning elements of a source. 
Spliterator.OfDouble A Spliterator specialized for double values. 
Spliterator.OfInt A Spliterator specialized for int values. 
Spliterator.OfLong A Spliterator specialized for long values. 
Spliterator.OfPrimitive<T, T_CONS, T_SPLITR extends OfPrimitive<T, T_CONS, T_SPLITR>> A Spliterator specialized for primitive values. 

Classes

AbstractCollection<E> This class provides a skeletal implementation of the Collection interface, to minimize the effort required to implement this interface. 
AbstractList<E> This class provides a skeletal implementation of the List interface to minimize the effort required to implement this interface backed by a "random access" data store (such as an array). 
AbstractMap<K, V> This class provides a skeletal implementation of the Map interface, to minimize the effort required to implement this interface. 
AbstractMap.SimpleEntry<K, V> An Entry maintaining a key and a value. 
AbstractMap.SimpleImmutableEntry<K, V> An Entry maintaining an immutable key and value. 
AbstractQueue<E> This class provides skeletal implementations of some Queue operations. 
AbstractSequentialList<E> This class provides a skeletal implementation of the List interface to minimize the effort required to implement this interface backed by a "sequential access" data store (such as a linked list). 
AbstractSet<E> This class provides a skeletal implementation of the Set interface to minimize the effort required to implement this interface. 
ArrayDeque<E> Resizable-array implementation of the Deque interface. 
ArrayList<E> Resizable-array implementation of the List interface. 
Arrays This class contains various methods for manipulating arrays (such as sorting and searching). 
Base64 This class consists exclusively of static methods for obtaining encoders and decoders for the Base64 encoding scheme. 
Base64.Decoder This class implements a decoder for decoding byte data using the Base64 encoding scheme as specified in RFC 4648 and RFC 2045. 
Base64.Encoder This class implements an encoder for encoding byte data using the Base64 encoding scheme as specified in RFC 4648 and RFC 2045. 
BitSet This class implements a vector of bits that grows as needed. 
Calendar The Calendar class is an abstract class that provides methods for converting between a specific instant in time and a set of calendar fields such as YEAR, MONTH, DAY_OF_MONTH, HOUR, and so on, and for manipulating the calendar fields, such as getting the date of the next week. 
Collections This class consists exclusively of static methods that operate on or return collections. 
Currency A currency corresponding to an ISO 4217 currency code such as "EUR" or "USD". 
Date The class Date represents a specific instant in time, with millisecond precision. 
Dictionary<K, V> The Dictionary class is the abstract parent of any class, such as Hashtable, which maps keys to values. 
DoubleSummaryStatistics A state object for collecting statistics such as count, min, max, sum, and average. 
EnumMap<K extends Enum<K>, V> A specialized Map implementation for use with enum type keys. 
EnumSet<E extends Enum<E>> A specialized Set implementation for use with enum types. 
EventListenerProxy<T extends EventListener> An abstract wrapper class for an EventListener class which associates a set of additional parameters with the listener. 
EventObject

The root class from which all event state objects shall be derived. 

FormattableFlags FomattableFlags are passed to the Formattable.formatTo() method and modify the output format for {@linkplain Formattable Formattables}. 
Formatter An interpreter for printf-style format strings. 
GregorianCalendar GregorianCalendar is a concrete subclass of Calendar and provides the standard calendar system used by most of the world. 
HashMap<K, V> Hash table based implementation of the Map interface. 
HashSet<E> This class implements the Set interface, backed by a hash table (actually a HashMap instance). 
Hashtable<K, V> This class implements a hash table, which maps keys to values. 
IdentityHashMap<K, V> This class implements the Map interface with a hash table, using reference-equality in place of object-equality when comparing keys (and values). 
IntSummaryStatistics A state object for collecting statistics such as count, min, max, sum, and average. 
LinkedHashMap<K, V>

Hash table and linked list implementation of the Map interface, with predictable iteration order. 

LinkedHashSet<E>

Hash table and linked list implementation of the Set interface, with predictable iteration order. 

LinkedList<E> Doubly-linked list implementation of the List and Deque interfaces. 
ListResourceBundle ListResourceBundle is an abstract subclass of ResourceBundle that manages resources for a locale in a convenient and easy to use list. 
Locale A Locale object represents a specific geographical, political, or cultural region. 
Locale.Builder Builder is used to build instances of Locale from values configured by the setters. 
LongSummaryStatistics A state object for collecting statistics such as count, min, max, sum, and average. 
Objects This class consists of static utility methods for operating on objects. 
Observable This class represents an observable object, or "data" in the model-view paradigm. 
Optional<T> A container object which may or may not contain a non-null value. 
OptionalDouble A container object which may or may not contain a double value. 
OptionalInt A container object which may or may not contain a int value. 
OptionalLong A container object which may or may not contain a long value. 
PriorityQueue<E> An unbounded priority {@linkplain Queue queue} based on a priority heap. 
Properties The Properties class represents a persistent set of properties. 
PropertyPermission Legacy security code; do not use.