Mac OS Runtime for Java is Apple's proprietary virtual machine

Java Virtual Machine

A Java virtual machine is a virtual machine capable of executing Java bytecode. It is the code execution component of the Java software platform. Sun Microsystems stated that there are over 4.5 billion JVM-enabled devices.-Overview:...

 for Java-based

Java (programming language)

Java is a programming language originally developed by James Gosling at Sun Microsystems 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 has a simpler object model and fewer low-level facilities...

 applications in "Classic" Mac OS

Mac OS

Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface...

 (i.e. versions prior to Mac OS X

Mac OS X

Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...

). Both a runtime environment and a software development kit

Software development kit

A software development kit is typically a set of software development tools that allows for the creation of applications for a certain software package, software framework, hardware platform, computer system, video game console, operating system, or similar platform.It may be something as simple...

 (SDK) are available.

The runtime environment includes a JIT compiler

Just-in-time compilation

In computing, just-in-time compilation , also known as dynamic translation, is a method to improve the runtime performance of computer programs. Historically, computer programs had two modes of runtime operation, either interpreted or static compilation...

 developed by Symantec

Symantec

Symantec Corporation is the largest maker of security software for computers. The company is headquartered in Mountain View, California, and is a Fortune 500 company and a member of the S&P 500 stock market index.-History:...

, the standard Java class library from Sun

Sun Microsystems

Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...

, additional classes providing Macintosh-specific functionality, and the Apple Applet Runner (a lightweight application for running Java applet

Applet

In computing, an applet is any small application that performs one specific task that runs within the scope of a larger program, often as a plug-in. An applet typically also refers to Java applets, i.e., programs written in the Java programming language that are included in a web page...

s without the overhead of a web browser

Web browser

A web browser is a software application for retrieving, presenting, and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier and may be a web page, image, video, or other piece of content...

). A number of web browsers could use MRJ to run Java applets in web pages, including Microsoft

Microsoft

Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...

 Internet Explorer

Internet Explorer

Windows Internet Explorer is a series of graphical web browsers developed by Microsoft and included as part of the Microsoft Windows line of operating systems, starting in 1995. It was first released as part of the add-on package Plus! for Windows 95 that year...

, iCab

ICab

iCab is a web browser for the Macintosh by Alexander Clauss, derived from Crystal Atari Browser for Atari TOS compatible computers. It is the most recently actively developed browser for 68k-based Macintoshes that features tabbed browsing and one of a very few browsers that was still updated in...

 and HotJava

HotJava

HotJava was a modular, extensible web browser from Sun Microsystems implemented in Java. It was the first browser to support Java applets, and was Sun's demonstration platform for the then new technology. It has since been discontinued and is now no longer supported...

.

The SDK includes ports

Porting

In computer science, porting is the process of adapting software so that an executable program can be created for a computing environment that is different from the one for which it was originally designed...

 of most of the tools from Sun's Java Development Kit

Java Development Kit

The Java Development Kit is an Oracle Corporation product aimed at Java developers. Since the introduction of Java, it has been by far the most widely used Java SDK. On 17 November 2006, Sun announced that it would be released under the GNU General Public License , thus making it free software...

 (in the form of MPW

Macintosh Programmer's Workshop

Macintosh Programmer's Workshop or MPW, is a software development environment for the Classic Mac OS, written by Apple Computer. For Macintosh developers, it was one of the primary tools for building applications for System 7.x and Mac OS 8.x and 9.x. Initially, MPW was sold as a commercial product...

 tools and Macintosh applications), additional tools for packaging Java applications as double-clickable Macintosh applications, libraries for Macintosh-specific functionality, and documentation for the MRJ-specific classes and tools.

Since the transition to Mac OS X, Apple has discontinued MRJ and instead maintains and distributes a port of Oracle's

Oracle Corporation

Oracle Corporation is an American multinational computer technology corporation that specializes in developing and marketing hardware systems and enterprise software products – particularly database management systems...

 HotSpot

HotSpot

HotSpot is a Java virtual machine for desktops and servers, maintained and distributed by Oracle Corporation. It features techniques such as just-in-time compilation and adaptive optimization designed to improve performance.-History:...

Java virtual machine.

External links

• Apple.com - Java