For an overview, API outline, and design rationale, please see:
For a tutorial and programming guide with examples of use of the collections framework, please see:
| Class | Description |
|---|---|
| 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, |
This class provides a skeletal implementation of the Map interface, to minimize the effort required to implement this interface. |
|
AbstractMap.SimpleEntry<K, |
An Entry maintaining a key and a value. |
|
AbstractMap.SimpleImmutableEntry<K, |
An unmodifiable Entry maintaining a key and a 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. |
| Calendar.Builder | Calendar.Builder is used for creating a Calendar from various date-time parameters. |
| Collection<E> | The root interface in the collection hierarchy. |
| Collections | This class consists exclusively of static methods that operate on or return collections. |
| Comparator<T> | A comparison function, which imposes a total ordering on some collection of objects. |
| ConcurrentModificationException | This exception may be thrown by methods that have detected concurrent modification of an object when such modification is not permissible. |
| Currency | Represents a currency. |
| Date | The class Date represents a specific instant in time, with millisecond precision. |
| Deque<E> | A linear collection that supports element insertion and removal at both ends. |
|
Dictionary<K, |
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. |
| DuplicateFormatFlagsException | Unchecked exception thrown when duplicate flags are provided in the format specifier. |
| EmptyStackException | Thrown by methods in the Stack class to indicate that the stack is empty. |
| Enumeration<E> | An object that implements the Enumeration interface generates a series of elements, one at a time. |
|
EnumMap<K extends Enum<K>, |
A specialized Map implementation for use with enum type keys. |
| EnumSet<E extends Enum<E>> | A specialized Set implementation for use with enum types. |
| EventListener | A tagging interface that all event listener interfaces must extend. |
| 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. |
| FormatFlagsConversionMismatchException | Unchecked exception thrown when a conversion and flag are incompatible. |
| FormatProcessorPREVIEW | Preview. This StringTemplate.ProcessorPREVIEW constructs a String result using Formatter specifications and values found in the StringTemplatePREVIEW. |
| Formattable | The Formattable interface must be implemented by any class that needs to perform custom formatting using the 's' conversion specifier of Formatter. |
| FormattableFlags | FormattableFlags are passed to the Formattable.formatTo() method and modify the output format for Formattables. |
| Formatter | An interpreter for printf-style format strings. |
| Formatter.BigDecimalLayoutForm | Enum for BigDecimal formatting. |
| FormatterClosedException | Unchecked exception thrown when the formatter has been closed. |
| GregorianCalendar | GregorianCalendar is a concrete subclass of Calendar and provides the standard calendar system used by most of the world. |
|
HashMap<K, |
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, |
This class implements a hash table, which maps keys to values. |
| HexFormat | HexFormat converts between bytes and chars and hex-encoded strings which may include additional formatting markup such as prefixes, suffixes, and delimiters. |
|
IdentityHashMap<K, |
This class implements the Map interface with a hash table, using reference-equality in place of object-equality when comparing keys (and values). |
| IllegalFormatCodePointException | Unchecked exception thrown when a character with an invalid Unicode code point as defined by Character.isValidCodePoint(int) is passed to the Formatter. |
| IllegalFormatConversionException | Unchecked exception thrown when the argument corresponding to the format specifier is of an incompatible type. |
| IllegalFormatException | Unchecked exception thrown when a format string contains an illegal syntax or a format specifier that is incompatible with the given arguments. |
| IllegalFormatFlagsException | Unchecked exception thrown when an illegal combination flags is given. |
| IllegalFormatPrecisionException | Unchecked exception thrown when the precision is a negative value other than -1, the conversion does not support a precision, or the value is otherwise unsupported. |
| IllegalFormatWidthException | Unchecked exception thrown when the format width is a negative value other than -1 or is otherwise unsupported. |
| IllformedLocaleException | Thrown by methods in Locale and Locale.Builder to indicate that an argument is not a well-formed BCP 47 tag. |
| InputMismatchException | Thrown by a Scanner to indicate that the token retrieved does not match the pattern for the expected type, or that the token is out of range for the expected type. |
| IntSummaryStatistics | A state object for collecting statistics such as count, min, max, sum, and average. |
| InvalidPropertiesFormatException | Thrown to indicate that an operation could not complete because the input did not conform to the appropriate XML document type for a collection of properties, as per the Properties specification. |
| Iterator<E> | An iterator over a collection. |
|
LinkedHashMap<K, |
Hash table and linked list implementation of the Map interface, with well-defined encounter order. |
| LinkedHashSet<E> | Hash table and linked list implementation of the Set interface, with well-defined encounter order. |
| LinkedList<E> | Doubly-linked list implementation of the List and Deque interfaces. |
| List<E> | An ordered collection, where the user has precise control over where in the list each element is inserted. |
| 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. |
| 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. |
| Locale.Category | Enum for locale categories. |
| Locale.FilteringMode | This enum provides constants to select a filtering mode for locale matching. |
| Locale.IsoCountryCode | Enum for specifying the type defined in ISO 3166. |
| Locale.LanguageRange | This class expresses a Language Range defined in RFC 4647 Matching of Language Tags. |
| LongSummaryStatistics | A state object for collecting statistics such as count, min, max, sum, and average. |
|
Map<K, |
An object that maps keys to values. |
|
Map.Entry<K, |
A map entry (key-value pair). |
| MissingFormatArgumentException | Unchecked exception thrown when there is a format specifier which does not have a corresponding argument or if an argument index refers to an argument that does not exist. |
| MissingFormatWidthException | Unchecked exception thrown when the format width is required. |
| MissingResourceException | Signals that a resource is missing. |
|
NavigableMap<K, |
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. |
| NoSuchElementException | Thrown by various accessor methods to indicate that the element being requested does not exist. |
| Objects | This class consists of static utility methods for operating on objects, or checking certain conditions before operation. |
| Observable | Deprecated. |
| Observer | Deprecated. This interface has been deprecated. |
| 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 an int value. |
| OptionalLong | A container object which may or may not contain a long value. |
|
PrimitiveIterator<T, |
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. |
| PriorityQueue<E> | An unbounded priority queue based on a priority heap. |
| Properties | The Properties class represents a persistent set of properties. |
| PropertyPermission | This class is for property permissions. |
| PropertyResourceBundle | PropertyResourceBundle is a concrete subclass of ResourceBundle that manages resources for a locale using a set of static strings from a property file. |
| Queue<E> | A collection designed for holding elements prior to processing. |
| Random | An instance of this class is used to generate a stream of pseudorandom numbers; its period is only 248. |
| RandomAccess | Marker interface used by List implementations to indicate that they support fast (generally constant time) random access. |
| ResourceBundle | Resource bundles contain locale-specific objects. |
| ResourceBundle.Control | ResourceBundle.Control defines a set of callback methods that are invoked by the ResourceBundle.getBundle factory methods during the bundle loading process. |
| Scanner | A simple text scanner which can parse primitive types and strings using regular expressions. |
| SequencedCollection<E> | A collection that has a well-defined encounter order, that supports operations at both ends, and that is reversible. |
|
SequencedMap<K, |
A Map that has a well-defined encounter order, that supports operations at both ends, and that is reversible. |
| SequencedSet<E> | A collection that is both a SequencedCollection and a Set. |
| ServiceConfigurationError | Error thrown when something goes wrong while locating, loading, or instantiating a service provider. |
| ServiceLoader<S> | A facility to load implementations of a service. |
| ServiceLoader.Provider<S> | Represents a service provider located by ServiceLoader. |
| Set<E> | A collection that contains no duplicate elements. |
| SimpleTimeZone | SimpleTimeZone is a concrete subclass of TimeZone that represents a time zone for use with a Gregorian calendar. |
|
SortedMap<K, |
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, |
A Spliterator specialized for primitive values. |
| Spliterators | Static classes and methods for operating on or creating instances of Spliterator and its primitive specializations Spliterator.OfInt, Spliterator.OfLong, and Spliterator.OfDouble. |
| Spliterators.AbstractDoubleSpliterator | An abstract Spliterator.OfDouble that implements trySplit to permit limited parallelism. |
| Spliterators.AbstractIntSpliterator | An abstract Spliterator.OfInt that implements trySplit to permit limited parallelism. |
| Spliterators.AbstractLongSpliterator | An abstract Spliterator.OfLong that implements trySplit to permit limited parallelism. |
| Spliterators.AbstractSpliterator<T> | An abstract Spliterator that implements trySplit to permit limited parallelism. |
| SplittableRandom | A generator of uniform pseudorandom values (with period 264) applicable for use in (among other contexts) isolated parallel computations that may generate subtasks. |
| Stack<E> | The Stack class represents a last-in-first-out (LIFO) stack of objects. |
| StringJoiner | StringJoiner is used to construct a sequence of characters separated by a delimiter and optionally starting with a supplied prefix and ending with a supplied suffix. |
| StringTokenizer | The string tokenizer class allows an application to break a string into tokens. |
| Timer | A facility for threads to schedule tasks for future execution in a background thread. |
| TimerTask | A task that can be scheduled for one-time or repeated execution by a Timer. |
| TimeZone | TimeZone represents a time zone offset, and also figures out daylight savings. |
| TooManyListenersException | The TooManyListenersException Exception is used as part of the Java Event model to annotate and implement a unicast special case of a multicast Event Source. |
|
TreeMap<K, |
A Red-Black tree based NavigableMap implementation. |
| TreeSet<E> | A NavigableSet implementation based on a TreeMap. |
| UnknownFormatConversionException | Unchecked exception thrown when an unknown conversion is given. |
| UnknownFormatFlagsException | Unchecked exception thrown when an unknown flag is given. |
| UUID | A class that represents an immutable universally unique identifier (UUID). |
| Vector<E> | The Vector class implements a growable array of objects. |
|
WeakHashMap<K, |
Hash table based implementation of the Map interface, with weak keys. |
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Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/package-summary.html
Observerinterface have been deprecated.