Java Platform, Standard Edition (Java SE) is a
computing platform
A computing platform, digital platform, or software platform is the infrastructure on which software is executed. While the individual components of a computing platform may be obfuscated under layers of abstraction, the ''summation of the requi ...
for development and deployment of
portable code for
desktop
A desktop traditionally refers to:
* The surface of a desk (often to distinguish office appliances that fit on a desk, such as photocopiers and printers, from larger equipment covering its own area on the floor)
Desktop may refer to various compu ...
and
server environments. Java SE was formerly known as Java 2 Platform, Standard Edition (J2SE).
The platform uses the
Java
Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...
programming language and is part of the
Java software-platform family. Java SE defines a range of general-purpose
API
An application programming interface (API) is a connection between computers or between computer programs. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build ...
s—such as
Java APIs for the
Java Class Library—and also includes the
Java Language Specification and the
Java Virtual Machine Specification.
OpenJDK
OpenJDK (Open Java Development Kit) is a free and open-source implementation of the Java Platform, Standard Edition (Java SE). It is the result of an effort Sun Microsystems began in 2006, four years before the company was acquired by Oracle Corp ...
is the official
reference implementation
In the software development process, a reference implementation (or, less frequently, sample implementation or model implementation) is a program that implements all requirements from a corresponding specification. The reference implementation ...
since version 7.
Nomenclature, standards and specifications
The platform was known as ''Java 2 Platform, Standard Edition'' or ''J2SE'' from version 1.2, until the name was changed to ''Java Platform, Standard Edition'' or ''Java SE'' in version 1.5. The "SE" is used to distinguish the base platform from the Enterprise Edition (
Java EE
Jakarta EE, formerly Java Platform, Enterprise Edition (Java EE) and Java 2 Platform, Enterprise Edition (J2EE), is a set of specifications, extending Java SE with specifications for enterprise features such as distributed computing and web serv ...
) and Micro Edition (
Java ME
Java Platform, Micro Edition or Java ME is a computing platform for development and deployment of porting, portable code for embedded system, embedded and mobile devices (micro-controllers, sensors, gateways, mobile phones, personal digita ...
) platforms. The "2" was originally intended to emphasize the major changes introduced in version 1.2, but was removed in version 1.6. The naming convention has been changed several times over the
Java version history
The Java language has undergone several changes since JDK 1.0 as well as numerous additions of classes and packages to the standard library. Since J2SE 1.4, the evolution of the Java language has been governed by the Java Community P ...
. Starting with J2SE 1.4 (Merlin), Java SE has been developed under the
Java Community Process
The Java Community Process (JCP), established in 1998, is a formal mechanism that enables interested parties to develop standard technical specifications for Java technology. Becoming a member of the JCP requires solid knowledge of the Java program ...
, which produces descriptions of proposed and final specifications for the Java platform called
Java Specification Requests (JSR). JSR 59 was the umbrella specification for J2SE 1.4 and JSR 176 specified J2SE 5.0 (Tiger). Java SE 6 (Mustang) was released under JSR 270.
Java Platform, Enterprise Edition
Jakarta EE, formerly Java Platform, Enterprise Edition (Java EE) and Java 2 Platform, Enterprise Edition (J2EE), is a set of specifications, extending Java SE with specifications for enterprise features such as distributed computing and web serv ...
(Java EE) is a related specification that includes all the
classes in Java SE, plus a number that are more useful to programs that run on
servers as opposed to
workstation
A workstation is a special computer designed for technical or computational science, scientific applications. Intended primarily to be used by a single user, they are commonly connected to a local area network and run multi-user operating syste ...
s.
Java Platform, Micro Edition
Java Platform, Micro Edition or Java ME is a computing platform for development and deployment of portable code for embedded and mobile devices (micro-controllers, sensors, gateways, mobile phones, personal digital assistants, TV set-top ...
(Java ME) is a related specification intended to provide a certified collection of Java APIs for the development of software for small, resource-constrained devices such as
cell phone
A mobile phone or cell phone is a portable telephone that allows users to make and receive calls over a radio frequency link while moving within a designated telephone service area, unlike fixed-location phones ( landline phones). This radio ...
s,
PDAs and
set-top box
A set-top box (STB), also known as a cable converter box, cable box, receiver, or simply box, and historically television decoder or a converter, is an information appliance device that generally contains a Tuner (radio)#Television, TV tuner inpu ...
es.
The
Java Runtime Environment (JRE) and
Java Development Kit (JDK) are the actual files downloaded and installed on a computer to run or develop Java programs, respectively.
General purpose packages
The majority of these packages are exported by the
java.base
module of the
Java Platform Module System (since Java 9).
java.lang
The
Java package
A Java package organizes Java classes into namespaces,
providing a unique namespace for each type it contains.
Classes in the same package can access each other's package-private and protected members.
In general, a package can contain the fo ...
contains fundamental classes and
interfaces
Interface or interfacing may refer to:
Academic journals
* ''Interface'' (journal), by the Electrochemical Society
* '' Interface, Journal of Applied Linguistics'', now merged with ''ITL International Journal of Applied Linguistics''
* '' Inter ...
closely tied to the language and
runtime system. This includes the root classes that form the
class hierarchy
A class hierarchy or inheritance tree in computer science is a classification of object types, denoting objects as the instantiations of classes (class is like a blueprint, the object is what is built from that blueprint) inter-relating the var ...
, types tied to the language definition, basic
exceptions, math functions,
threading, security functions, as well as some information on the underlying native system. This package contains 22 of 32
Error
classes provided in JDK 6.
The main classes and interfaces in
java.lang
are:
* – the class that is the root of every class hierarchy.
* – the base class for
enumeration classes (as of J2SE 5.0).
* – the class that is the root of the Java
reflection system.
* – the class that is the base class of the exception class hierarchy.
* , , and – the base classes for each exception type.
* – the class that allows operations on threads.
* – the class for
strings and
string literal
string literal or anonymous string is a literal for a string value in the source code of a computer program. Modern programming languages commonly use a quoted sequence of characters, formally "bracketed delimiters", as in x = "foo", where , "foo ...
s.
* and – classes for performing
string manipulation (
StringBuilder
as of J2SE 5.0).
* – the interface that allows generic comparison and ordering of objects (as of J2SE 1.2).
* – the interface that allows generic iteration using the
enhanced for
loop (as of J2SE 5.0).
* , , , , and – classes that provide "system operations" that manage the
dynamic loading of classes, creation of external
processes, host environment inquiries such as the time of day, and enforcement of
security policies
Security policy is a definition of what it means to ''be secure'' for a system, organization or other entity. For an organization, it addresses the constraints on behavior of its members as well as constraints imposed on adversaries by mechanisms ...
.
* and – classes that provide basic math functions such as
sine
In mathematics, sine and cosine are trigonometric functions of an angle. The sine and cosine of an acute angle are defined in the context of a right triangle: for the specified angle, its sine is the ratio of the length of the side opposite th ...
,
cosine
In mathematics, sine and cosine are trigonometric functions of an angle. The sine and cosine of an acute angle are defined in the context of a right triangle: for the specified angle, its sine is the ratio of the length of the side opposite that ...
, and
square root
In mathematics, a square root of a number is a number such that y^2 = x; in other words, a number whose ''square'' (the result of multiplying the number by itself, or y \cdot y) is . For example, 4 and −4 are square roots of 16 because 4 ...
(
StrictMath
as of J2SE 1.3).
* The
primitive wrapper classes that
encapsulate primitive types as
objects.
* The basic exception classes thrown for language-level and other common exceptions.
Classes in
java.lang
are automatically imported into every
source file
In computing, source code, or simply code or source, is a plain text computer program written in a programming language. A programmer writes the human readable source code to control the behavior of a computer.
Since a computer, at base, onl ...
.
java.lang.ref
The package provides more flexible types of
references
A reference is a relationship between Object (philosophy), objects in which one object designates, or acts as a means by which to connect to or link to, another object. The first object in this relation is said to ''refer to'' the second object. ...
than are otherwise available, permitting limited interaction between the application and the
Java Virtual Machine
A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java bytecode. The JVM is detailed by a specification that formally descr ...
(JVM)
garbage collector. It is an important package, central enough to the language for the language designers to give it a name that starts with "java.lang", but it is somewhat special-purpose and not used by a lot of developers. This package was added in J2SE 1.2.
Java has an expressive system of references and allows for special behavior for garbage collection. A normal reference in Java is known as a "strong reference". The
java.lang.ref
package defines three other types of references—soft,
weak
Weak may refer to:
Songs
* Weak (AJR song), "Weak" (AJR song), 2016
* Weak (Melanie C song), "Weak" (Melanie C song), 2011
* Weak (SWV song), "Weak" (SWV song), 1993
* Weak (Skunk Anansie song), "Weak" (Skunk Anansie song), 1995
* "Weak", a son ...
, and phantom references. Each type of reference is designed for a specific use.
* A can be used to implement a
cache. An object that is not reachable by a strong reference (that is, not strongly reachable), but is referenced by a soft reference is called "softly reachable". A softly reachable object may be garbage collected at the discretion of the garbage collector. This generally means that softly reachable objects are only garbage collected when free memory is low—but again, this is at the garbage collector's discretion. Semantically, a soft reference means, "Keep this object when nothing else references it, unless the memory is needed."
* A is used to implement weak maps. An object that is not strongly or softly reachable, but is referenced by a weak reference is called "
weakly reachable". A weakly reachable object is garbage collected in the next collection cycle. This behavior is used in the class . A weak map allows the programmer to put key/value pairs in the map and not worry about the objects taking up memory when the key is no longer reachable anywhere else. Another possible application of weak references is the
string intern pool. Semantically, a weak reference means "get rid of this object when nothing else references it at the next garbage collection."
* A is used to reference objects that have been marked for garbage collection and have been
finalized, but have not yet been reclaimed. An object that is not strongly, softly or weakly reachable, but is referenced by a phantom reference is called "phantom reachable." This allows for more flexible cleanup than is possible with the finalization mechanism alone. Semantically, a phantom reference means "this object is no longer needed and has been finalized in preparation for being collected."
Each of these reference types extends the class, which provides the
method
Method (, methodos, from μετά/meta "in pursuit or quest of" + ὁδός/hodos "a method, system; a way or manner" of doing, saying, etc.), literally means a pursuit of knowledge, investigation, mode of prosecuting such inquiry, or system. In re ...
to return a strong reference to the referent object (or
null
if the reference has been cleared or if the reference type is phantom), and the method to clear the reference.
The
java.lang.ref
also defines the class , which can be used in each of the applications discussed above to keep track of objects that have changed reference type. When a
Reference
is created it is optionally registered with a reference queue. The application polls the reference queue to get references that have changed reachability state.
java.lang.reflect
Reflection is a constituent of the
Java
Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...
API that lets Java code examine and "reflect" on Java components at runtime and use the reflected members. Classes in the package, along with
java.lang.Class
and accommodate applications such as
debugger
A debugger is a computer program used to test and debug other programs (the "target" programs). Common features of debuggers include the ability to run or halt the target program using breakpoints, step through code line by line, and display ...
s,
interpreters
Interpreting is translation from a spoken or signed language into another language, usually in real time to facilitate live communication. It is distinguished from the translation of a written text, which can be more deliberative and make use o ...
, object inspectors,
class browser
{{Unreferenced, date=July 2010
A class browser is a feature of an integrated development environment (IDE) that allows the programmer to browse, navigate, or visualize the structure of object-oriented programming code.
History
Most modern clas ...
s, and services such as object
serialization
In computing, serialization (or serialisation, also referred to as pickling in Python (programming language), Python) is the process of translating a data structure or object (computer science), object state into a format that can be stored (e. ...
and
JavaBeans that need access to either the public members of a target object (based on its runtime class) or the members declared by a given class. This package was added in JDK 1.1.
Reflection is used to instantiate classes and invoke methods using their names, a concept that allows for dynamic programming. Classes, interfaces, methods,
fields
Fields may refer to:
Music
*Fields (band), an indie rock band formed in 2006
* Fields (progressive rock band), a progressive rock band formed in 1971
* ''Fields'' (album), an LP by Swedish-based indie rock band Junip (2010)
* "Fields", a song by ...
, and
constructors can all be discovered and used at runtime. Reflection is supported by
metadata
Metadata (or metainformation) is "data that provides information about other data", but not the content of the data itself, such as the text of a message or the image itself. There are many distinct types of metadata, including:
* Descriptive ...
that the JVM has about the program.
= Techniques
=
There are basic techniques involved in reflection:
* Discovery – this involves taking an object or class and discovering the members, superclasses, implemented interfaces, and then possibly using the discovered elements.
* Use by name – involves starting with the symbolic name of an element and using the named element.
Discovery
Discovery typically starts with an object and calling the method to get the object's
Class
. The
Class
object has several methods for discovering the contents of the class, for example:
* – returns an array of objects representing all the public methods of the class or interface
* – returns an array of objects representing all the public constructors of the class
* – returns an array of objects representing all the public fields of the class or interface
* – returns an array of
Class
objects representing all the public classes and interfaces that are members (e.g.
inner class In object-oriented programming (OOP), an inner class or nested class is a class declared entirely within the body of another class or interface. It is distinguished from a subclass.
Overview
An instance of a normal or top-level class can exist on ...
es) of the class or interface
* – returns the
Class
object representing the superclass of the class or interface (
null
is returned for interfaces)
* – returns an array of
Class
objects representing all the interfaces that are implemented by the class or interface
Use by name
The
Class
object can be obtained either through discovery, by using the ''class literal'' (e.g.
MyClass.class
) or by using the name of the class (e.g. ). With a
Class
object, member
Method
,
Constructor
, or
Field
objects can be obtained using the symbolic name of the member. For example:
* – returns the
Method
object representing the public method with the name "methodName" of the class or interface that accepts the parameters specified by the
Class...
parameters.
* – returns the
Constructor
object representing the public constructor of the class that accepts the parameters specified by the
Class...
parameters.
* – returns the
Field
object representing the public field with the name "fieldName" of the class or interface.
Method
,
Constructor
, and
Field
objects can be used to dynamically access the represented member of the class. For example:
* – returns an
Object
containing the value of the field from the instance of the object passed to
get()
. (If the
Field
object represents a static field then the
Object
parameter is ignored and may be
null
.)
* – returns an
Object
containing the result of invoking the method for the instance of the first
Object
parameter passed to
invoke()
. The remaining
Object...
parameters are passed to the method. (If the
Method
object represents a
static method
A method in object-oriented programming (OOP) is a procedure associated with an object, and generally also a message. An object consists of ''state data'' and ''behavior''; these compose an ''interface'', which specifies how the object may be us ...
then the first
Object
parameter is ignored and may be
null
.)
* – returns the new
Object
instance from invoking the constructor. The
Object...
parameters are passed to the constructor. (Note that the parameterless constructor for a class can also be invoked by calling .)
= Arrays and proxies
=
The
java.lang.reflect
package also provides an class that contains static methods for creating and manipulating array objects, and since J2SE 1.3, a class that supports dynamic creation of proxy classes that implement specified interfaces.
The implementation of a
Proxy
class is provided by a supplied object that implements the interface. The
InvocationHandler
's method is called for each method invoked on the proxy object—the first parameter is the proxy object, the second parameter is the
Method
object representing the method from the interface implemented by the proxy, and the third parameter is the array of parameters passed to the interface method. The
invoke()
method returns an
Object
result that contains the result returned to the code that called the proxy interface method.
java.io
The package contains classes that support
input and output
In computing, input/output (I/O, i/o, or informally io or IO) is the communication between an information processing system, such as a computer, and the outside world, such as another computer system, peripherals, or a human operator. Inputs ar ...
. The classes in the package are primarily
stream-oriented; however, a class for
random access
Random access (also called direct access) is the ability to access an arbitrary element of a sequence in equal time or any datum from a population of addressable elements roughly as easily and efficiently as any other, no matter how many elemen ...
files is also provided. The central classes in the package are and , which are
abstract base classes for reading from and writing to
byte stream
A bitstream (or bit stream), also known as binary sequence, is a sequence of bits.
A bytestream is a sequence of bytes. Typically, each byte is an Octet (computing), 8-bit quantity, and so the term octet stream is sometimes used interchangeab ...
s, respectively. The related classes and are abstract base classes for reading from and writing to
character streams, respectively. The package also has a few miscellaneous classes to support interactions with the host
file system.
Streams
The stream classes follow the
decorator pattern by extending the base subclass to add features to the stream classes. Subclasses of the base stream classes are typically named for one of the following attributes:
* the source/destination of the stream data
* the type of data written to/read from the stream
* additional processing or filtering performed on the stream data
The stream subclasses are named using the naming
pattern
A pattern is a regularity in the world, in human-made design, or in abstract ideas. As such, the elements of a pattern repeat in a predictable manner. A geometric pattern is a kind of pattern formed of geometric shapes and typically repeated l ...
''XxxStreamType''
where
''Xxx''
is the name describing the feature and
''StreamType''
is one of
InputStream
,
OutputStream
,
Reader
, or
Writer
.
The following table shows the sources/destinations supported directly by the
java.io
package:
Other standard library packages provide stream implementations for other destinations, such as the
InputStream
returned by the method or the Java EE class.
Data type handling and processing or filtering of stream data is accomplished through stream
filters
Filtration is a physical process that separates solid matter and fluid from a mixture.
Filter, filtering, filters or filtration may also refer to:
Science and technology
Computing
* Filter (higher-order function), in functional programming
* Fil ...
. The filter classes all accept another compatible stream object as a parameter to the constructor and ''decorate'' the enclosed stream with additional features. Filters are created by extending one of the base filter classes , , , or .
The
Reader
and
Writer
classes are really just byte streams with additional processing performed on the data stream to convert the bytes to characters. They use the default
character encoding
Character encoding is the process of assigning numbers to graphical character (computing), characters, especially the written characters of human language, allowing them to be stored, transmitted, and transformed using computers. The numerical v ...
for the platform, which as of J2SE 5.0 is represented by the returned by the static method. The class converts an
InputStream
to a
Reader
and the class converts an
OutputStream
to a
Writer
. Both these classes have constructors that support specifying the character encoding to use. If no encoding is specified, the program uses the default encoding for the platform.
The following table shows the other processes and filters that the
java.io
package directly supports. All these classes extend the corresponding
Filter
class.
Random access
The class supports ''
random access
Random access (also called direct access) is the ability to access an arbitrary element of a sequence in equal time or any datum from a population of addressable elements roughly as easily and efficiently as any other, no matter how many elemen ...
'' reading and writing of files. The class uses a ''
file pointer'' that represents a byte-offset within the file for the next read or write operation. The file pointer is moved implicitly by reading or writing and explicitly by calling the or methods. The current position of the file pointer is returned by the method.
File system
The class represents a
file or
directory path
A path is a route for physical travel – see Trail.
Path or PATH may also refer to:
Physical paths of different types
* Bicycle path
* Bridle path, used by people on horseback
* Course (navigation), the intended path of a vehicle
* Desir ...
in a
file system.
File
objects support the creation, deletion and renaming of files and directories and the manipulation of
file attribute
File attributes are a type of metadata that describe and may modify how files and/or directories in a filesystem behave. Typical file attributes may, for example, indicate or specify whether a file is visible, modifiable, compressed, or encrypte ...
s such as ''read-only'' and ''last modified timestamp''.
File
objects that represent directories can be used to get a list of all the contained files and directories.
The class is a
file descriptor
In Unix and Unix-like computer operating systems, a file descriptor (FD, less frequently fildes) is a process-unique identifier (handle) for a file or other input/output resource, such as a pipe or network socket.
File descriptors typically h ...
that represents a source or sink (destination) of bytes. Typically this is a file, but can also be a
console
Console may refer to:
Computing and video games
* System console, a physical device to operate a computer
** Virtual console, a user interface for multiple computer consoles on one device
** Command-line interface, a method of interacting with ...
or
network socket
A network socket is a software structure within a network node of a computer network that serves as an endpoint for sending and receiving data across the network. The structure and properties of a socket are defined by an application programming ...
.
FileDescriptor
objects are used to create
File
streams. They are obtained from
File
streams and
java.net
sockets and datagram sockets.
java.nio
In J2SE 1.4, the package (NIO or Non-blocking I/O) was added to support
memory-mapped I/O
Memory-mapped I/O (MMIO) and port-mapped I/O (PMIO) are two complementary methods of performing input/output (I/O) between the central processing unit (CPU) and peripheral devices in a computer (often mediating access via chipset). An altern ...
, facilitating
I/O operations closer to the underlying hardware with sometimes dramatically better performance. The
java.nio
package provides support for a number of buffer types. The subpackage provides support for different
character encoding
Character encoding is the process of assigning numbers to graphical character (computing), characters, especially the written characters of human language, allowing them to be stored, transmitted, and transformed using computers. The numerical v ...
s for character data. The subpackage provides support for ''channels,'' which represent connections to entities that are capable of performing I/O operations, such as files and sockets. The
java.nio.channels
package also provides support for fine-grained locking of files.
java.math
The package supports
multiprecision arithmetic (including modular arithmetic operations) and provides multiprecision prime number generators used for cryptographic key generation. The main classes of the package are:
* – provides arbitrary-precision signed decimal numbers.
BigDecimal
gives the user control over rounding behavior through
RoundingMode
.
* – provides arbitrary-precision integers. Operations on
BigInteger
do not
overflow or lose precision. In addition to standard arithmetic operations, it provides
modular arithmetic
In mathematics, modular arithmetic is a system of arithmetic operations for integers, other than the usual ones from elementary arithmetic, where numbers "wrap around" when reaching a certain value, called the modulus. The modern approach to mo ...
,
GCD calculation,
primality testing
A primality test is an algorithm for determining whether an input number is prime. Among other fields of mathematics, it is used for cryptography. Unlike integer factorization, primality tests do not generally give prime factors, only stating wheth ...
,
prime number
A prime number (or a prime) is a natural number greater than 1 that is not a Product (mathematics), product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime ...
generation,
bit manipulation, and other miscellaneous operations.
* – encapsulate the context settings that describe certain rules for numerical operators.
* – an enumeration that provides eight rounding behaviors.
java.net
The package provides special IO routines for networks, allowing
HTTP
HTTP (Hypertext Transfer Protocol) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, wher ...
requests, as well as other common transactions.
java.text
The package implements parsing routines for strings and supports various human-readable languages and locale-specific parsing.
java.util
Data structure
In computer science, a data structure is a data organization and storage format that is usually chosen for Efficiency, efficient Data access, access to data. More precisely, a data structure is a collection of data values, the relationships amo ...
s that aggregate objects are the focus of the package. Included in the package is the
Collections API, an organized data structure hierarchy influenced heavily by the
design patterns
''Design Patterns: Elements of Reusable Object-Oriented Software'' (1994) is a software engineering book describing software design patterns. The book was written by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides, with a fore ...
considerations.
Special purpose packages
java.applet
Created to support
Java applet
Java applets were applet, small applications written in the Java (programming language), Java programming language, or another programming language that Compiled language, compiles to Java bytecode, and delivered to users in the form of Ja ...
creation, the package lets applications be downloaded over a network and run within a guarded sandbox. Security restrictions are easily imposed on the sandbox. A developer, for example, may apply a
digital signature to an applet, thereby labeling it as safe. Doing so allows the user to grant the applet permission to perform restricted operations (such as accessing the local hard drive), and removes some or all the sandbox restrictions. Digital certificates are issued by
certificate authorities.
Because Java applets are now deprecated, this package is itself deprecated.
java.beans
Included in the package are various classes for developing and manipulating beans, reusable components defined by the
JavaBeans architecture. The architecture provides mechanisms for manipulating properties of components and firing events when those properties change.
The APIs in
java.beans
are intended for use by a bean editing tool, in which beans can be combined, customized, and manipulated. One type of bean editor is a
GUI designer in an
integrated development environment
An integrated development environment (IDE) is a Application software, software application that provides comprehensive facilities for software development. An IDE normally consists of at least a source-code editor, build automation tools, an ...
.
java.awt
The , or Abstract Window Toolkit, provides access to a basic set of
GUI widgets based on the underlying native platform's widget set, the core of the GUI event subsystem, and the interface between the native windowing system and the Java application. It also provides several basic
layout manager Layout managers are software components used in widget toolkits which have the ability to lay out graphical control elements by their relative positions without using distance units. It is often more natural to define component layouts in this mann ...
s, a datatransfer package for use with the
Clipboard and
Drag and Drop
In computer graphical user interfaces, drag and drop is a pointing device gesture in which the user (computing), user selects a virtual object by "grabbing" it and dragging it to a different location or onto another virtual object. In general, i ...
, the interface to
input device
In computing, an input device is a piece of equipment used to provide data and control signals to an information processing system, such as a computer or information appliance. Examples of input devices include keyboards, computer mice, scanne ...
s such as
mice
A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...
and
keyboards, as well as access to the
system tray
The taskbar is a graphical user interface element that has been part of Microsoft Windows since Windows 95, displaying and facilitating switching between running computer program, programs. The taskbar and the associated Start menu, Start Menu were ...
on supporting systems. This package, along with
javax.swing
contains the largest number of enums (7 in all) in JDK 6.
java.rmi
The package provides
Java remote method invocation
The Java Remote Method Invocation (Java RMI) is a Java API that performs remote method invocation, the object-oriented equivalent of remote procedure calls (RPC), with support for direct transfer of serialized Java classes and distributed garb ...
to support
remote procedure call
In distributed computing, a remote procedure call (RPC) is when a computer program causes a procedure (subroutine) to execute in a different address space (commonly on another computer on a shared computer network), which is written as if it were a ...
s between two java applications running in different
JVM
A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java bytecode. The JVM is detailed by a specification that formally descri ...
s.
java.security
Support for security, including the message digest algorithm, is included in the package.
java.sql
An implementation of the
JDBC
Java Database Connectivity (JDBC) is an application programming interface (API) for the Java (programming language), Java programming language which defines how a client may access a database. It is a Java-based data access technology used for Java ...
API (used to access
SQL
Structured Query Language (SQL) (pronounced ''S-Q-L''; or alternatively as "sequel")
is a domain-specific language used to manage data, especially in a relational database management system (RDBMS). It is particularly useful in handling s ...
database
In computing, a database is an organized collection of data or a type of data store based on the use of a database management system (DBMS), the software that interacts with end users, applications, and the database itself to capture and a ...
s) is grouped into the package.
javax.rmi
The
javax.rmi
/code> package provided support for the remote communication between applications, using the RMI over IIOP protocol. This protocol combines RMI and CORBA features.
Java SE Core Technologies - CORBA / RMI-IIOP
javax.swing
Swing is a collection of routines that build on java.awt
to provide a platform independent widget toolkit
A widget toolkit, widget library, GUI toolkit, or UX library is a library (computing), library or a collection of libraries containing a set of graphical control elements (called ''widgets'') used to construct the graphical user interface (GUI) of ...
. uses the 2D drawing routines to render the user interface components instead of relying on the underlying native operating system
An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs.
Time-sharing operating systems scheduler (computing), schedule tasks for ...
GUI support.
This package contains the largest number of classes (133 in all) in JDK 6. This package, along with java.awt
also contains the largest number of enums (7 in all) in JDK 6. It supports pluggable looks and feels (PLAFs) so that widgets in the GUI can imitate those from the underlying native system. Design patterns permeate the system, especially a modification of the model–view–controller
Model–view–controller (MVC) is a software architectural pattern commonly used for developing user interfaces that divides the related program logic into three interconnected elements. These elements are:
* the model, the internal representat ...
pattern, which loosens the coupling between function and appearance. One inconsistency is that (as of J2SE 1.3) fonts are drawn by the underlying native system, and not by Java, limiting text portability. Workarounds, such as using bitmap fonts, do exist. In general, "layouts" are used and keep elements within an aesthetically consistent GUI across platforms.
javax.swing.text.html.parser
The package provides the error tolerant HTML parser that is used for writing various web browsers and web bots.
javax.xml.bind.annotation
The javax.xml.bind.annotation
/code> package contained the largest number of Annotation Types (30 in all) in JDK 6. It defines annotations for customizing Java program elements to XML Schema mapping.
OMG packages
org.omg.CORBA
The
/code> package provided support for the remote communication between applications using the General Inter-ORB Protocol and supports other features of the common object request broker architecture
The Common Object Request Broker Architecture (CORBA) is a standard defined by the Object Management Group (OMG) designed to facilitate the communication of systems that are deployed on diverse platforms. CORBA enables collaboration between sy ...
. Same as RMI and RMI-IIOP, this package is for calling remote methods of objects on other virtual machines (usually via network).
This package contained the largest number of Exception
classes (45 in all) in JDK 6. From all communication possibilities CORBA is portable between various languages; however, with this comes more complexity.
These packages were deprecated in Java 9 and removed from Java 11.
org.omg.PortableInterceptor
The org.omg.PortableInterceptor
/code> package contained the largest number of interfaces (39 in all) in JDK 6. It provides a mechanism to register ORB hooks through which ORB services intercept the normal flow of execution of the ORB.
Security
Several critical security vulnerabilities have been reported. Security alerts from Oracle announce critical security-related patches to Java SE.
References
External links
*
JSR 270
(Java SE 6)
1.8
1.7
1.6
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Computing platforms
Platform, Standard Edition
Platform, Standard Edition