Android APIs
Added in API level 1
package

java.util

Interfaces

Collection<E> Collection is the root of the collection hierarchy. 
Comparator<T> A Comparator is used to compare two objects to determine their ordering with respect to each other. 
Deque<E> A linear collection that supports element insertion and removal at both ends. 
Enumeration<E> A legacy iteration interface. 
EventListener EventListener is the superclass of all event listener interfaces. 
Formattable Classes that handle custom formatting for the 's' specifier of Formatter should implement the Formattable interface. 
Iterator<E> An iterator over a sequence of objects, such as a collection. 
List<E> A List is a collection which maintains an ordering for its elements. 
ListIterator<E> An ListIterator is used to sequence over a List of objects. 
Map<K, V> A Map is a data structure consisting of a set of keys and values in which each key is mapped to a single value. 
Map.Entry<K, V> Map.Entry is a key/value mapping contained in a Map. 
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 Observer is the interface to be implemented by objects that receive notification of updates on an Observable object. 
Queue<E> A collection designed for holding elements prior to processing. 
RandomAccess RandomAccess is implemented by List implementations that support fast (usually constant time) random access. 
Set<E> A Set is a data structure which does not allow duplicate elements. 
SortedMap<K, V> A map that has its keys ordered. 
SortedSet<E> SortedSet is a Set which iterates over its elements in a sorted order. 

Classes

AbstractCollection<E> Class AbstractCollection is an abstract implementation of the Collection interface. 
AbstractList<E> AbstractList is an abstract implementation of the List interface, optimized for a backing store which supports random access. 
AbstractMap<K, V> A base class for Map implementations. 
AbstractMap.SimpleEntry<K, V> A key-value mapping with mutable values. 
AbstractMap.SimpleImmutableEntry<K, V> An immutable key-value mapping. 
AbstractQueue<E> This class provides skeletal implementations of some Queue operations. 
AbstractSequentialList<E> AbstractSequentialList is an abstract implementation of the List interface. 
AbstractSet<E> An AbstractSet is an abstract implementation of the Set interface. 
ArrayDeque<E> Resizable-array implementation of the Deque interface. 
ArrayList<E> ArrayList is an implementation of List, backed by an array. 
Arrays Arrays contains static methods which operate on arrays. 
BitSet The BitSet class implements a bit array. 
Calendar Calendar 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. 
Collections Collections contains static methods which operate on Collection classes. 
Currency A currency corresponding to an ISO 4217 currency code such as "EUR" or "USD". 
Date A specific moment in time, with millisecond precision. 
Dictionary<K, V> Note: Do not use this class since it is obsolete. 
EnumMap<K extends Enum<K>, V> An Map specialized for use with Enum types as keys. 
EnumSet<E extends Enum<E>> An EnumSet is a specialized Set to be used with enums as keys. 
EventListenerProxy This abstract class provides a simple wrapper for objects of type EventListener. 
EventObject EventObjects represent events. 
FormattableFlags FormattableFlags are used as a parameter to formatTo(Formatter, int, int, int) and change the output format in Formattables. 
Formatter Formats arguments according to a format string (like printf in C). 
GregorianCalendar GregorianCalendar is a concrete subclass of Calendar and provides the standard calendar used by most of the world. 
HashMap<K, V> HashMap is an implementation of Map. 
HashSet<E> HashSet is an implementation of a Set. 
Hashtable<K, V> Hashtable is a synchronized implementation of Map. 
IdentityHashMap<K, V> IdentityHashMap is a variant on HashMap which tests equality by reference instead of equality by value. 
LinkedHashMap<K, V> LinkedHashMap is an implementation of Map that guarantees iteration order. 
LinkedHashSet<E> LinkedHashSet is a variant of HashSet. 
LinkedList<E> LinkedList is an implementation of List, backed by a doubly-linked list. 
ListResourceBundle ListResourceBundle is the abstract superclass of classes which provide resources by implementing the getContents() method to return the list of resources. 
Locale Locale represents a language/country/variant combination. 
Locale.Builder A class that helps construct Locale instances. 
Objects Utility methods for objects. 
Observable Observable is used to notify a group of Observer objects when a change occurs. 
PriorityQueue<E> A 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. 
Properties A Properties object is a Hashtable where the keys and values must be Strings. 
PropertyPermission Legacy security code; do not use. 
PropertyResourceBundle PropertyResourceBundle loads resources from an InputStream. 
Random This class provides methods that return pseudo-random values. 
ResourceBundle ResourceBundle is an abstract class which is the superclass of classes which provide Locale-specific resources. 
ResourceBundle.Control ResourceBundle.Control is a static utility class defines ResourceBundle load access methods, its default access order is as the same as before. 
Scanner A parser that parses a text string of primitive types and strings with the help of regular expressions. 
ServiceLoader<S> A service-provider loader. 
SimpleTimeZone SimpleTimeZone is a concrete subclass of TimeZone that represents a time zone for use with a Gregorian calendar. 
Stack<E> Stack is a Last-In/First-Out(LIFO) data structure which represents a stack of objects. 
StringTokenizer Breaks a string into tokens; new code should probably use split(String). 
Timer Timers schedule one-shot or recurring tasks for execution. 
TimerTask The TimerTask class represents a task to run at a specified time. 
TimeZone TimeZone represents a time zone, primarily used for configuring a Calendar or SimpleDateFormat instance. 
TreeMap<K, V> A map whose entries are sorted by their keys. 
TreeSet<E> TreeSet is an implementation of SortedSet. 
UUID UUID is an immutable representation of a 128-bit universally unique identifier (UUID). 
Vector<E> Vector is an implementation of List, backed by an array and synchronized. 
WeakHashMap<K, V> WeakHashMap is an implementation of Map with keys which are WeakReferences. 

Enums

Formatter.BigDecimalLayoutForm The enumeration giving the available styles for formatting very large decimal numbers. 

Exceptions

ConcurrentModificationException An ConcurrentModificationException is thrown when a Collection is modified and an existing iterator on the Collection is used to modify the Collection as well. 
DuplicateFormatFlagsException The unchecked exception will be thrown out if there are duplicate flags given out in the format specifier. 
EmptyStackException An EmptyStackException is thrown if the pop/peek method of a stack is executed on an empty stack. 
FormatFlagsConversionMismatchException A FormatFlagsConversionMismatchException will be thrown if a conversion and the flags are incompatible. 
FormatterClosedException A FormatterClosedException will be thrown if the formatter has been closed. 
IllegalFormatCodePointException An IllegalFormatCodePointException will be thrown if an invalid Unicode code point (defined by isValidCodePoint(int)) is passed as a parameter to a Formatter. 
IllegalFormatConversionException An IllegalFormatConversionException will be thrown when the parameter is incompatible with the corresponding format specifier. 
IllegalFormatException An IllegalFormatException is thrown when a format string that contains either an illegal syntax or format specifier is transferred as a parameter. 
IllegalFormatFlagsException An IllegalFormatFlagsException will be thrown if the combination of the format flags is illegal. 
IllegalFormatPrecisionException An IllegalFormatPrecisionException will be thrown if the precision is a negative other than -1 or in other cases where precision is not supported. 
IllegalFormatWidthException An IllegalFormatWidthException will be thrown if the width is a negative value other than -1 or in other cases where a width is not supported. 
IllformedLocaleException Thrown when a locale subtag or field is not well formed. 
InputMismatchException An InputMismatchException is thrown by a scanner to indicate that the next token does not match or is out of range for the type specified in the pattern. 
InvalidPropertiesFormatException An InvalidPropertiesFormatException is thrown if loading the XML document defining the properties does not follow the Properties specification. 
MissingFormatArgumentException A MissingFormatArgumentException will be thrown if there is no corresponding argument with the specified conversion or an argument index that refers to a missing argument. 
MissingFormatWidthException A MissingFormatWidthException will be thrown if the format width is missing but is required. 
MissingResourceException A MissingResourceException is thrown by ResourceBundle when a resource bundle cannot be found or a resource is missing from a resource bundle. 
NoSuchElementException Thrown when trying to retrieve an element past the end of an Enumeration or Iterator. 
TooManyListenersException A TooManyListenersException is thrown when an attempt is made to add more than one listener to an event source which only supports a single listener. 
UnknownFormatConversionException An UnknownFormatConversionException will be thrown if the format conversion is unknown. 
UnknownFormatFlagsException An UnknownFormatFlagsException will be thrown if there is an unknown flag. 

Errors

ServiceConfigurationError Thrown when a service provider can't be loaded by ServiceLoader.