Java is a general-purpose
computer programming language that is
concurrent,
class-based,
object-oriented, and specifically designed to have as few implementation dependencies as possible. It is intended to let application developers "
write once, run anywhere" (WORA),
[15] meaning that
compiled Java code can run on all platforms that support Java without the need for recompilation.
[16] Java applications are typically compiled to
bytecode that can run on any
Java virtual machine (JVM) regardless of
computer architecture. As of 2016, Java is one of the most
popular programming languages in use,
[17][18][19][20] particularly for client-server web applications, with a reported 9 million developers.
[21] Java was originally developed by
James Gosling at
Sun Microsystems (which has since been
acquired by Oracle Corporation) and released in 1995 as a core component of Sun Microsystems'
Java platform. The language derives much of its
syntax from
C and
C++, but it has fewer
low-level facilities than either of them.
The original and
reference implementation Java
compilers, virtual machines, and
class libraries were originally released by Sun under proprietary licenses. As of May 2007, in compliance with the specifications of the
Java Community Process, Sun
relicensed most of its Java technologies under the
GNU General Public License. Others have also developed alternative implementations of these Sun technologies, such as the
GNU Compiler for Java (bytecode compiler),
GNU Classpath (standard libraries), and
IcedTea-Web (browser plugin for applets).
The latest version is
Java 8 which is the only version currently supported for free by Oracle, although earlier versions are supported both by Oracle and other companies on a commercial basis.
History
James Gosling, Mike Sheridan, and
Patrick Naughton initiated the Java language project in June 1991.
[22] Java was originally designed for interactive television, but it was too advanced for the digital cable television industry at the time.
[23] The language was initially called
Oak after an
oak tree that stood outside Gosling's office. Later the project went by the name
Green and was finally renamed
Java, from
Java coffee.
[24] Gosling designed Java with a C/C++-style syntax that system and application programmers would find familiar.
[25] Sun Microsystems released the first public implementation as Java 1.0 in 1995.
[26] It promised "Write Once, Run Anywhere" (WORA), providing no-cost run-times on popular
platforms. Fairly secure and featuring configurable security, it allowed network- and file-access restrictions. Major
web browsers soon incorporated the ability to run
Java applets within web pages, and Java quickly became popular. The Java 1.0 compiler was re-written
in Java by
Arthur van Hoff to comply strictly with the Java 1.0 language specification.
[27] With the advent of
Java 2 (released initially as J2SE 1.2 in December 1998 – 1999), new versions had multiple configurations built for different types of platforms.
J2EE included technologies and APIs for enterprise applications typically run in server environments, while
J2ME featured APIs optimized for mobile applications. The desktop version was renamed
J2SE. In 2006, for marketing purposes, Sun renamed new
J2 versions as
Java EE,
Java ME, and
Java SE, respectively.
In 1997, Sun Microsystems approached the
ISO/IEC JTC 1 standards body and later the
Ecma International to formalize Java, but it soon withdrew from the process.
[28][29][30] Java remains a
de facto standard, controlled through the
Java Community Process.
[31] At one time, Sun made most of its Java implementations available without charge, despite their
proprietary software status. Sun generated revenue from Java through the selling of licenses for specialized products such as the Java Enterprise System.
On November 13, 2006, Sun released much of its Java virtual machine (JVM) as
free and open-source software, (FOSS), under the terms of the
GNU General Public License (GPL). On May 8, 2007, Sun finished the process, making all of its JVM's core code available under
free software/open-source distribution terms, aside from a small portion of code to which Sun did not hold the copyright.
[32] Sun's vice-president Rich Green said that Sun's ideal role with regard to Java was as an "evangelist".
[33] Following
Oracle Corporation's acquisition of Sun Microsystems in 2009–10, Oracle has described itself as the "steward of Java technology with a relentless commitment to fostering a community of participation and transparency".
[34] This did not prevent Oracle from filing a lawsuit against Google shortly after that for using Java inside the Android SDK (see Google section below). Java software runs on everything from
laptops to
data centers,
game consoles to scientific
supercomputers.
[35] On April 2, 2010, James Gosling resigned from Oracle.
[36] In January 2016, Oracle announced that Java runtime environments based on JDK 9 will discontinue the browser plugin.
[37] Principles
There were five primary goals in the creation of the Java language:
[16] - It must be "simple, object-oriented, and familiar".
- It must be "robust and secure".
- It must be "architecture-neutral and portable".
- It must execute with "high performance".
- It must be "interpreted, threaded, and dynamic".
Versions
As of 2015, only Java 8 is officially supported. Major release versions of Java, along with their release dates:
- JDK 1.0 (January 23, 1996)[38]
- JDK 1.1 (February 19, 1997)
- J2SE 1.2 (December 8, 1998)
- J2SE 1.3 (May 8, 2000)
- J2SE 1.4 (February 6, 2002)
- J2SE 5.0 (September 30, 2004)
- Java SE 6 (December 11, 2006)
- Java SE 7 (July 28, 2011)
- Java SE 8 (March 18, 2014)
Practices
Java platform
One design goal of Java is portability, which means that programs written for the Java platform must run similarly on any combination of hardware and operating system with adequate runtime support. This is achieved by compiling the Java language code to an intermediate representation called
Java bytecode, instead of directly to architecture-specific
machine code. Java bytecode instructions are analogous to machine code, but they are intended to be executed by a
virtual machine (VM) written specifically for the host hardware.
End users commonly use a
Java Runtime Environment (JRE) installed on their own machine for standalone Java applications, or in a web browser for Java
applets.
Standard libraries provide a generic way to access host-specific features such as graphics,
threading, and
networking.
The use of universal bytecode makes porting simple. However, the overhead of interpreting bytecode into machine instructions made interpreted programs almost always run more slowly than native
executables.
Just-in-time (JIT) compilers that compile bytecodes to machine code during runtime were introduced from an early stage. Java itself is platform-independent and is adapted to the particular platform it is to run on by a
Java virtual machine for it, which translates the
Java bytecode into the platform's machine language.
[39] Implementations
Oracle Corporation is the current owner of the official implementation of the Java SE platform, following their acquisition of
Sun Microsystems on January 27, 2010. This implementation is based on the original implementation of Java by Sun. The Oracle implementation is available for
Microsoft Windows (still works for XP, while only later versions currently officially supported),
macOS,
Linux, and
Solaris. Because Java lacks any formal standardization recognized by
Ecma International, ISO/IEC, ANSI, or other third-party standards organization, the Oracle implementation is the
de facto standard.
The Oracle implementation is packaged into two different distributions: The Java Runtime Environment (JRE) which contains the parts of the Java SE platform required to run Java programs and is intended for end users, and the
Java Development Kit (JDK), which is intended for software developers and includes development tools such as the
Java compiler,
Javadoc,
Jar, and a
debugger.
OpenJDK is another notable Java SE implementation that is licensed under the GNU GPL. The implementation started when Sun began releasing the Java source code under the GPL. As of Java SE 7, OpenJDK is the official Java reference implementation.
The goal of Java is to make all implementations of Java compatible. Historically, Sun's trademark license for usage of the Java brand insists that all implementations be "compatible". This resulted in a legal dispute with
Microsoft after Sun claimed that the Microsoft implementation did not support
RMI or
JNI and had added platform-specific features of their own. Sun sued in 1997, and, in 2001, won a settlement of US$20 million, as well as a court order enforcing the terms of the license from Sun.
[40] As a result, Microsoft no longer ships Java with
Windows.
Platform-independent Java is essential to
Java EE, and an even more rigorous validation is required to certify an implementation. This environment enables portable server-side applications.
Performance
Programs written in Java have a reputation for being slower and requiring more memory than those written in C++.
[41][42] However, Java programs' execution speed improved significantly with the introduction of
just-in-time compilation in 1997/1998 for
Java 1.1,
[43] the addition of language features supporting better code analysis (such as inner classes, the StringBuilder class, optional assertions, etc.), and optimizations in the Java virtual machine, such as
HotSpot becoming the default for Sun's JVM in 2000. With Java 1.5, the performance was improved with the addition of the java.util.concurrent package, including
Lock free implementations of the
ConcurrentMaps and other multi-core collections, and it was improved further Java 1.6.
Some platforms offer direct hardware support for Java; there are microcontrollers that can run Java in hardware instead of a software Java virtual machine
[citation needed], and some
ARM based processors could have hardware support for executing Java bytecode through their
Jazelle option, though support has mostly been dropped in current implementations of ARM.
Automatic memory management
Java uses an
automatic garbage collector to manage memory in the
object lifecycle. The programmer determines when objects are created, and the Java runtime is responsible for recovering the memory once objects are no longer in use. Once no references to an object remain, the
unreachable memory becomes eligible to be freed automatically by the garbage collector. Something similar to a
memory leak may still occur if a programmer's code holds a reference to an object that is no longer needed, typically when objects that are no longer needed are stored in containers that are still in use. If methods for a nonexistent object are called, a "null pointer exception" is thrown.
[44][45] One of the ideas behind Java's automatic memory management model is that programmers can be spared the burden of having to perform manual memory management. In some languages, memory for the creation of objects is implicitly allocated on the
stack or explicitly allocated and deallocated from the
heap. In the latter case, the responsibility of managing memory resides with the programmer. If the program does not deallocate an object, a
memory leak occurs. If the program attempts to access or deallocate memory that has already been deallocated, the result is undefined and difficult to predict, and the program is likely to become unstable and/or crash. This can be partially remedied by the use of
smart pointers, but these add overhead and complexity. Note that garbage collection does not prevent "logical" memory leaks,
i.e., those where the memory is still referenced but never used.
Garbage collection may happen at any time. Ideally, it will occur when a program is idle. It is guaranteed to be triggered if there is insufficient free memory on the heap to allocate a new object; this can cause a program to stall momentarily. Explicit memory management is not possible in Java.
Java does not support C/C++ style
pointer arithmetic, where object addresses and unsigned integers (usually long integers) can be used interchangeably. This allows the garbage collector to relocate referenced objects and ensures type safety and security.
As in C++ and some other object-oriented languages, variables of Java's
primitive data types are either stored directly in fields (for objects) or on the
stack (for methods) rather than on the heap, as is commonly true for non-primitive data types (but see
escape analysis). This was a conscious decision by Java's designers for performance reasons.
Java contains multiple types of garbage collectors. By default, HotSpot uses the
parallel scavenge garbage collector.
[46] However, there are also several other garbage collectors that can be used to manage the heap. For 90% of applications in Java, the
Concurrent Mark-Sweep (CMS) garbage collector is sufficient.
[47] Oracle aims to replace CMS with the
Garbage-First collector (G1).
[48] Syntax
The syntax of Java is largely influenced by
C++. Unlike C++, which combines the syntax for structured, generic, and object-oriented programming, Java was built almost exclusively as an object-oriented language.
[16] All code is written inside classes, and every data item is an object, with the exception of the primitive data types, (
i.e. integers, floating-point numbers,
boolean values, and characters), which are not objects for performance reasons. Java reuses some popular aspects of C++ (such as printf() method).
Unlike C++, Java does not support
operator overloading[49] or
multiple inheritance for
classes, though multiple inheritance is supported for
interfaces.
[50] This simplifies the language and aids in preventing potential errors and
anti-pattern design.
[citation needed] Java uses comments similar to those of C++. There are three different styles of comments: a single line style marked with two slashes (
//), a multiple line style opened with
/* and closed with
*/, and the
Javadoc commenting style opened with
/** and closed with
*/. The Javadoc style of commenting allows the user to run the Javadoc executable to create documentation for the program and can be read by some
integrated development environments (IDEs) such as
Eclipse to allow developers to access documentation within the IDE.
Example: // This is an example of a single line comment using two slashes
/* This is an example of a multiple line comment using the slash and asterisk.
This type of comment can be used to hold a lot of information or deactivate
code, but it is very important to remember to close the comment. */
package fibsandlies;
import java.util.HashMap;
/**
* This is an example of a Javadoc comment; Javadoc can compile documentation
* from this text. Javadoc comments must immediately precede the class, method, or field being documented.
*/
public class FibCalculator extends Fibonacci implements Calculator {
private static Map<Integer, Integer> memoized = new HashMap<Integer, Integer>();
/*
* The main method written as follows is used by the JVM as a starting point for the program.
*/
public static void main(String[] args) {
memoized.put(1, 1);
memoized.put(2, 1);
System.out.println(fibonacci(12)); //Get the 12th Fibonacci number and print to console
}
/**
* An example of a method written in Java, wrapped in a class.
* Given a non-negative number FIBINDEX, returns
* the Nth Fibonacci number, where N equals FIBINDEX.
* @param fibIndex The index of the Fibonacci number
* @return The Fibonacci number
*/
public static int fibonacci(int fibIndex) {
if (memoized.containsKey(fibIndex)) {
return memoized.get(fibIndex);
} else {
int answer = fibonacci(fibIndex - 1) + fibonacci(fibIndex - 2);
memoized.put(fibIndex, answer);
return answer;
}
}
}
"Hello world" example
The traditional
"Hello, world!" program can be written in Java as:
[51] class HelloWorldApp {
public static void main(String[] args) {
System.out.println("Hello World!"); // Prints the string to the console.
}
}
Source files must be named after the public class they contain, appending the suffix
.java, for example,
HelloWorldApp.java. It must first be compiled into bytecode, using a
Java compiler, producing a file named
HelloWorldApp.class. Only then can it be executed, or "launched". The Java source file may only contain one public class, but it can contain multiple classes with other than public access and any number of public
inner classes. When the source file contains multiple classes, make one class "public" and name the source file with that public class name.
A
class that is not declared
public may be stored in any .java file. The compiler will generate a class file for each class defined in the source file. The name of the class file is the name of the class, with
.class appended. For class file generation,
anonymous classes are treated as if their name were the concatenation of the name of their enclosing class, a
$, and an integer.
The
keyword public denotes that a method can be called from code in other classes, or that a class may be used by classes outside the class hierarchy. The class hierarchy is related to the name of the directory in which the .java file is located. This is called an access level modifier. Other access level modifiers include the keywords
private and
protected.
The keyword
static in front of a method indicates a
static method, which is associated only with the class and not with any specific instance of that class. Only static methods can be invoked without a reference to an object. Static methods cannot access any class members that are not also static. Methods that are not designated static are instance methods and require a specific instance of a class to operate.
The keyword
void indicates that the main method does not return any value to the caller. If a Java program is to exit with an error code, it must call System.exit() explicitly.
The method name "
main" is not a keyword in the Java language. It is simply the name of the method the Java launcher calls to pass control to the program. Java classes that run in managed environments such as applets and
Enterprise JavaBeans do not use or need a
main() method. A Java program may contain multiple classes that have
main methods, which means that the VM needs to be explicitly told which class to launch from.
The main method must accept an
array of
String objects. By convention, it is referenced as
args although any other legal identifier name can be used. Since Java 5, the main method can also use
variable arguments, in the form of
public static void main(String... args), allowing the main method to be invoked with an arbitrary number of
String arguments. The effect of this alternate declaration is semantically identical (the
args parameter is still an array of
String objects), but it allows an alternative syntax for creating and passing the array.
The Java launcher launches Java by loading a given class (specified on the command line or as an attribute in a
JAR) and starting its
public static void main(String[]) method. Stand-alone programs must declare this method explicitly. The
String[] args parameter is an
array of
String objects containing any arguments passed to the class. The parameters to
main are often passed by means of a
command line.
Printing is part of a Java standard library: The
System class defines a public static field called
out. The
out object is an instance of the
PrintStream class and provides many methods for printing data to
standard out, including
println(String) which also appends a new line to the passed string.
The string "Hello World!" is automatically converted to a String object by the compiler.
Special classes
Applet
Java applets are programs that are
embedded in other applications, typically in a Web page displayed in a web browser.
// Hello.java
import javax.swing.JApplet;
import java.awt.Graphics;
public class Hello extends JApplet {
public void paintComponent(final Graphics g) {
g.drawString("Hello, world!", 65, 95);
}
}
The
import statements direct the
Java compiler to include the
javax.swing.JApplet and
java.awt.Graphics classes in the compilation. The import statement allows these classes to be referenced in the
source code using the
simple class name (i.e.
JApplet) instead of the
fully qualified class name (
FQCN, i.e.
javax.swing.JApplet).
The
Hello class
extends (
subclasses) the
JApplet (Java Applet) class; the
JApplet class provides the framework for the host application to display and control the
lifecycle of the applet. The
JApplet class is a JComponent (Java Graphical Component) which provides the applet with the capability to display a
graphical user interface (GUI) and respond to user
events.
The
Hello class
overrides the
paintComponent(Graphics) method (additionally indicated with the
annotation, supported as of JDK 1.5,
Override) inherited from the
Container superclass to provide the code to display the applet. The
paintComponent() method is passed a
Graphics object that contains the graphic context used to display the applet. The
paintComponent() method calls the graphic context
drawString(String, int, int) method to display the
"Hello, world!" string at a
pixel offset of (
65, 95) from the upper-left corner in the applet's display.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<!-- Hello.html -->
<html>
<head>
<title>Hello World Applet</title>
</head>
<body>
<applet code="Hello.class" width="200" height="200">
</applet>
</body>
</html>
An applet is placed in an
HTML document using the
<applet> HTML element. The
applet tag has three attributes set:
code="Hello" specifies the name of the
JApplet class and
width="200" height="200" sets the pixel width and height of the applet. Applets may also be embedded in HTML using either the
object or
embed element,
[52] although support for these elements by web browsers is inconsistent.
[53] However, the
applet tag is deprecated, so the
object tag is preferred where supported.
The host application, typically a Web browser, instantiates the
Hello applet and creates an
AppletContext for the applet. Once the applet has initialized itself, it is added to the AWT display hierarchy. The
paintComponent() method is called by the AWT
event dispatching thread whenever the display needs the applet to draw itself.
Servlet
Java Servlet technology provides Web developers with a simple, consistent mechanism for extending the functionality of a Web server and for accessing existing business systems. Servlets are
server-side Java EE components that generate responses (typically
HTML pages) to requests (typically
HTTP requests) from
clients. A servlet can almost be thought of as an applet that runs on the server side—without a face.
// Hello.java
import java.io.*;
import javax.servlet.*;
public class Hello extends GenericServlet {
public void service(final ServletRequest request, final ServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
final PrintWriter pw = response.getWriter();
try {
pw.println("Hello, world!");
} finally {
pw.close();
}
}
}
The
import statements direct the Java compiler to include all the public classes and
interfaces from the
java.io and
javax.servlet packages in the compilation. Packages make Java well suited for large scale applications.
The
Hello class
extends the
GenericServlet class; the
GenericServlet class provides the interface for the
server to forward requests to the servlet and control the servlet's lifecycle.
The
Hello class overrides the
service(ServletRequest, ServletResponse) method defined by the
Servlet interface to provide the code for the service request handler. The
service() method is passed: a
ServletRequest object that contains the request from the client and a
ServletResponse object used to create the response returned to the client. The
service() method declares that it
throws the
exceptions ServletException and
IOException if a problem prevents it from responding to the request.
The
setContentType(String) method in the response object is called to set the
MIME content type of the returned data to
"text/html". The
getWriter() method in the response returns a
PrintWriter object that is used to write the data that is sent to the client. The
println(String) method is called to write the
"Hello, world!" string to the response and then the
close() method is called to close the print writer, which causes the data that has been written to the stream to be returned to the client.
JavaServer Pages
JavaServer Pages (JSP) are
server-side Java EE components that generate responses, typically
HTML pages, to
HTTP requests from
clients. JSPs embed Java code in an HTML page by using the special
delimiters <% and
%>. A JSP is compiled to a Java
servlet, a Java application in its own right, the first time it is accessed. After that, the generated servlet creates the response.
Swing application
Swing is a graphical user interface
library for the Java SE platform. It is possible to specify a different look and feel through the
pluggable look and feel system of Swing. Clones of
Windows,
GTK+, and
Motif are supplied by Sun.
Apple also provides an
Aqua look and feel for
macOS. Where prior implementations of these looks and feels may have been considered lacking, Swing in Java SE 6 addresses this problem by using more native
GUI widget drawing routines of the underlying platforms.
This example Swing application creates a single window with "Hello, world!" inside:
// Hello.java (Java SE 5)
import javax.swing.*;
public class Hello extends JFrame {
public Hello() {
super("hello");
super.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
super.add(new JLabel("Hello, world!"));
super.pack();
super.setVisible(true);
}
public static void main(final String[] args) {
new Hello();
}
}
The first
import includes all the public classes and interfaces from the
javax.swing package.
The
Hello class
extends the
JFrame class; the
JFrame class implements a
window with a
title bar and a close
control.
The
Hello() constructor initializes the frame by first calling the superclass constructor, passing the parameter
"hello", which is used as the window's title. It then calls the
setDefaultCloseOperation(int) method inherited from
JFrame to set the default operation when the close control on the title bar is selected to
WindowConstants.EXIT_ON_CLOSE – this causes the
JFrame to be disposed of when the frame is closed (as opposed to merely hidden), which allows the Java virtual machine to exit and the program to terminate. Next, a
JLabel is created for the string
"Hello, world!" and the
add(Component) method inherited from the
Container superclass is called to add the label to the frame. The
pack() method inherited from the
Window superclass is called to size the window and lay out its contents.
The
main() method is called by the Java virtual machine when the program starts. It
instantiates a new
Hello frame and causes it to be displayed by calling the
setVisible(boolean) method inherited from the
Component superclass with the boolean parameter
true. Once the frame is displayed, exiting the
main method does not cause the program to terminate because the AWT
event dispatching thread remains active until all of the Swing top-level windows have been disposed.
Generics
In 2004,
generics were added to the Java language, as part of J2SE 5.0. Prior to the introduction of generics, each variable declaration had to be of a specific type. For container classes, for example, this is a problem because there is no easy way to create a container that accepts only specific types of objects. Either the container operates on all subtypes of a class or interface, usually
Object, or a different container class has to be created for each contained class. Generics allow compile-time type checking without having to create many container classes, each containing almost identical code. In addition to enabling more efficient code, certain runtime exceptions are prevented from occurring, by issuing compile-time errors. If Java prevented all runtime type errors (
ClassCastException's) from occurring, it would be
type safe.
In 2016, the type system was shown not to be safe at all, it was proven
unsound.
[54] Criticism
Criticisms directed at Java include the implementation of generics,
[55] speed,
[56] the handling of unsigned numbers,
[57] the implementation of floating-point arithmetic,
[58] and a history of security vulnerabilities in the primary Java VM implementation
HotSpot.
[59] Use outside of the Java platform
The Java programming language requires the presence of a software platform in order for compiled programs to be executed. Oracle supplies the
Java platform for use with Java. The
Android SDK is an alternative software platform, used primarily for developing
Android applications.
Android
The
Android operating system makes extensive use of Java-related technology.
The Java language is a key pillar in
Android, an
open source mobile operating system. Although Android, built on the
Linux kernel, is written largely in C, the
Android SDK uses the Java language as the basis for Android applications. The bytecode language supported by the Android SDK is incompatible with Java bytecode and runs on its own virtual machine, optimized for low-memory devices such as
smartphones and
tablet computers. Depending on the Android version, the bytecode is either interpreted by the
Dalvik virtual machine or compiled into native code by the
Android Runtime.
Android does not provide the full Java SE standard library, although the Android SDK does include an independent implementation of a large subset of it. It supports Java 6 and some Java 7 features, offering an implementation compatible with the standard library (
Apache Harmony).
Controversy
The use of Java-related technology in Android led to a legal dispute between Oracle and Google. On May 7, 2012, a San Francisco jury found that if APIs could be copyrighted, then Google had infringed Oracle's copyrights by the use of Java in Android devices.
[60] District Judge
William Haskell Alsup ruled on May 31, 2012, that APIs cannot be copyrighted,
[61] but this was reversed by the United States Court of Appeals for the Federal Circuit in May 2014.
[62] On May 26, 2016, the district court decided in favor of Google, ruling the copyright infringement of the Java API in Android constitutes fair use.
[63] Class libraries
The
Java Class Library is the
standard library, developed to support application development in Java. It is controlled by
Sun Microsystems in cooperation with others through the
Java Community Process program. Companies or individuals participating in this process can influence the design and development of the APIs. This process has been a subject of controversy.
[when?] The class library contains features such as:
- The core libraries, which include:
- The integration libraries, which allow the application writer to communicate with external systems. These libraries include:
- User interface libraries, which include:
- The (heavyweight, or native) Abstract Window Toolkit (AWT), which provides GUI components, the means for laying out those components and the means for handling events from those components
- The (lightweight) Swing libraries, which are built on AWT but provide (non-native) implementations of the AWT widgetry
- APIs for audio capture, processing, and playback
- JavaFX
- A platform dependent implementation of the Java virtual machine that is the means by which the bytecodes of the Java libraries and third party applications are executed
- Plugins, which enable applets to be run in web browsers
- Java Web Start, which allows Java applications to be efficiently distributed to end users across the Internet
- Licensing and documentation
Documentation
Javadoc is a comprehensive documentation system, created by
Sun Microsystems, used by many Java developers
[by whom?]. It provides developers with an organized system for documenting their code. Javadoc comments have an extra asterisk at the beginning, i.e. the delimiters are
/** and
*/, whereas the normal multi-line comments in Java are set off with the delimiters
/* and
*/.
Editions
Sun has defined and supports four editions of Java targeting different application environments and segmented many of its
APIs so that they belong to one of the platforms. The platforms are:
The
classes in the Java APIs are organized into separate groups called
packages. Each package contains a set of related
interfaces, classes, and
exceptions. Refer to the separate platforms for a description of the packages available.
[relevant to this section? – discuss] Sun also provided an edition called
PersonalJava that has been superseded by later, standards-based Java ME configuration-profile pairings.
