Not to be confused with. Java: (),,,,, (now owned by ) First appeared May 23, 1995; 22 years ago ( 1995-05-23),,,.java,, Website Major, (GCJ),, Influenced by,,,,,,,,,, Influenced,,,,,,,,,,,,,,,,,, • at Wikibooks Java is a general-purpose that is,,, and specifically designed to have as few implementation dependencies as possible. It is intended to let application developers ' (WORA), meaning that Java code can run on all platforms that support Java without the need for recompilation. Java applications are typically compiled to that can run on any (JVM) regardless of. As of 2016, Java is one of the most, particularly for client-server web applications, with a reported 9 million developers. Java was originally developed by at (which has since been ) and released in 1995 as a core component of Sun Microsystems'. The language derives much of its from and, but it has fewer facilities than either of them.

The original and Java, virtual machines, and were originally released by Sun under proprietary licenses. As of May 2007, in compliance with the specifications of the, Sun most of its Java technologies under the. Others have also developed alternative implementations of these Sun technologies, such as the (bytecode compiler), (standard libraries), and -Web (browser plugin for applets). The latest version is, released on September 21, 2017, and is one of the two versions currently supported for free by Oracle.

Sun Microsystems, Inc., has intellectual property rights relating to implementations of the technology described in this publication. In particular, and without limitation, these intellectual property rights may include one or more U.S. Patents, foreign patents, or pending applications. Sun, Sun Microsys- tems, the Sun Logo, Java. The Information Assurance (IA) mission at the National Security Agency (NSA) serves a role unlike that of any other U.S. Keylauncher Ps2 Download. Government entity. National Security.

Versions earlier than Java 8 are supported by companies on a commercial basis; e.g. By Oracle back to Java 6 as of October 2017 (while they still 'highly recommend that you uninstall' [ ] pre-Java 8 from at least Windows computers).

The graph from 2002 to 2015. Over the course of a decade Java (blue) and C (black) competing for the top position., Mike Sheridan, and initiated the Java language project in June 1991. Java was originally designed for interactive television, but it was too advanced for the digital cable television industry at the time. The language was initially called after an tree that stood outside Gosling's office. Later the project went by the name Green and was finally renamed Java, from. Gosling designed Java with a C/C++-style syntax that system and application programmers would find familiar. Released the first public implementation as Java 1.0 in 1995.

It promised 'Write Once, Run Anywhere' (WORA), providing no-cost run-times on popular. Fairly secure and featuring configurable security, it allowed network- and file-access restrictions. Major soon incorporated the ability to run within web pages, and Java quickly became popular. The Java 1.0 compiler was re-written by to comply strictly with the Java 1.0 language specification. 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,, and, respectively.

In 1997, Sun Microsystems approached the standards body and later the to formalize Java, but it soon withdrew from the process. Java remains a, controlled through the. At one time, Sun made most of its Java implementations available without charge, despite their 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, (FOSS), under the terms of the (GPL). On May 8, 2007, Sun finished the process, making all of its JVM's core code available under /open-source distribution terms, aside from a small portion of code to which Sun did not hold the copyright. Sun's vice-president Rich Green said that Sun's ideal role with regard to Java was as an 'evangelist'.

Following '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'. 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, to scientific. On April 2, 2010, James Gosling resigned from Oracle.

In January 2016, Oracle announced that Java runtime environments based on JDK 9 will discontinue the browser plugin. Principles There were five primary goals in the creation of the Java language: • 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'. Main articles: and 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, instead of directly to architecture-specific. Java bytecode instructions are analogous to machine code, but they are intended to be executed by a (VM) written specifically for the host hardware.

Commonly use a (JRE) installed on their own machine for standalone Java applications, or in a web browser for Java. Standard libraries provide a generic way to access host-specific features such as graphics,, and. 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. (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 for it, which translates the into the platform's machine language.

See also: is the current owner of the official implementation of the Java SE platform, following their acquisition of on January 27, 2010. This implementation is based on the original implementation of Java by Sun.

The Oracle implementation is available for (still works for XP, while only later versions currently officially supported),,, and. Because Java lacks any formal standardization recognized by, ISO/IEC, ANSI, or other third-party standards organization, the Oracle implementation is the. 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 (JDK), which is intended for software developers and includes development tools such as the,,, and a. 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 after Sun claimed that the Microsoft implementation did not support or 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. As a result, Microsoft no longer ships Java with.

Platform-independent Java is essential to, and an even more rigorous validation is required to certify an implementation. This environment enables portable server-side applications. Main article: Programs written in Java have a reputation for being slower and requiring more memory than those written in C++.

However, Java programs' execution speed improved significantly with the introduction of in 1997/1998 for, 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 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 implementations of the and other multi-core collections, and it was improved further with 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 [ ], and some based processors could have hardware support for executing Java bytecode through their option, though support has mostly been dropped in current implementations of ARM. Automatic memory management Java uses an to manage memory in the. 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 becomes eligible to be freed automatically by the garbage collector. Something similar to a 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. 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 or explicitly allocated and deallocated from the. In the latter case, the responsibility of managing memory resides with the programmer. If the program does not deallocate an object, a 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 or crash. This can be partially remedied by the use of, 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, 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 are either stored directly in fields (for objects) or on the (for methods) rather than on the heap, as is commonly true for non-primitive data types (but see ). This was a conscious decision by Java's designers for performance reasons. Java contains multiple types of garbage collectors. By default, HotSpot uses the. However, there are also several other garbage collectors that can be used to manage the heap.

For 90% of applications in Java, the (CMS) garbage collector is sufficient. Oracle aims to replace CMS with the (G1). Main article: The syntax of Java is largely influenced.

Unlike C++, which combines the syntax for structured, generic, and object-oriented programming, Java was built almost exclusively as an object-oriented language. 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,, 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 or for classes, though multiple inheritance is supported for. 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 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 (IDEs) such as to allow developers to access documentation within the IDE. Hello World Applet An applet is placed in an document using the. The applet tag has three attributes set: code='Hello.class' 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, although support for these elements by web browsers is inconsistent. 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 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 whenever the display needs the applet to draw itself. Main article: is a graphical user interface for the Java SE platform. It is possible to specify a different look and feel through the system of Swing. Clones of,, and are supplied by Sun. Also provides an look and feel for.

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 drawing routines of the underlying platforms. This example Swing application creates a single window with 'Hello, world!' Main article: In 2004, 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. In 2016, the type system was shown not to be safe at all, it was proven. Main article: Criticisms directed at Java include the implementation of generics, speed, the handling of unsigned numbers, the implementation of floating-point arithmetic, and a history of security vulnerabilities in the primary Java VM implementation.

Use outside 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 for use with Java. The is an alternative software platform, used primarily for developing.

The operating system makes extensive use of Java-related technology. The Java language is a key pillar in, an. Although Android, built on the, is written largely in C, the 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 and. Depending on the Android version, the bytecode is either interpreted by the or compiled into native code by the. 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 ().

See also: 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. District Judge ruled on May 31, 2012, that APIs cannot be copyrighted, but this was reversed by the United States Court of Appeals for the Federal Circuit in May 2014. 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. Class libraries. Main article: The is the, developed to support application development in Java.

It is controlled by in cooperation with others through the 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. [ ] The class library contains features such as: • The core libraries, which include: • IO/NIO • Networking • • • • Scripting/Compiler • (Lambda, Streaming) • that implement such as,,,, and, or • Processing (Parsing, Transforming, Validating) libraries • • libraries • The integration libraries, which allow the application writer to communicate with external systems. • • • Sun has defined and supports four editions of Java targeting different application environments and segmented many of its so that they belong to one of the platforms. The platforms are: • for smartcards. • (Java ME) – targeting environments with limited resources.

• (Java SE) – targeting workstation environments. • (Java EE) – targeting large distributed enterprise or Internet environments. The in the Java APIs are organized into separate groups called. Each package contains a set of related, classes, and. Refer to the separate platforms for a description of the packages available. [ – ] Sun also provided an edition called that has been superseded by later, standards-based Java ME configuration-profile pairings.

• Binstock, Andrew (May 20, 2015).. Retrieved March 18, 2016.

• Chaudhary, Harry H. Retrieved 2016-05-29. • Java 5.0 added several new language features (the,, and ), after they were introduced in the similar (and competing) language. • Gosling, James; McGilton, Henry (May 1996).. • Gosling, James; Joy, Bill; Steele, Guy; Bracha, Gilad.. Archived from on January 5, 2009. Retrieved June 9, 2010.

• stated on a number of public occasions, e.g. In a lecture at the Polytechnic Museum, Moscow in September 2005 (several independent first-hand accounts in Russian exist, e.g. One with an audio recording: Filippova, Elena (September 22, 2005).. ), that the Sun Java design team licensed the Oberon compiler sources a number of years prior to the release of Java and examined it: a (relative) compactness, type safety, garbage collection, no multiple inheritance for classes – all these key overall design features are shared by Java and Oberon. • cites as a strong influence on the design of the Java programming language, stating that notable direct derivatives include Java interfaces (derived from Objective-C's ) and primitive wrapper classes.

• TechMetrix Research (1999). Java Application Servers Report. Archived from (PDF) on December 29, 2010. The project went ahead under the name 'green' and the language was based on an old model of, which makes it possible to generate interpretive code •.

August 31, 2004. Retrieved 2010-06-09. • In the summer of 1996, Sun was designing the precursor to what is now the event model of the AWT and the JavaBeans TM component architecture. Borland contributed greatly to this process. We looked very carefully at Delphi Object Pascal and built a working prototype of bound method references in order to understand their interaction with the Java programming language and its APIs. Retrieved 2016-01-14.

Gambas Website. Retrieved 2017-10-09. March 26, 2014. Retrieved 2015-01-11. Retrieved 2009-07-27. January 1, 1999.

Retrieved 2013-01-14. • McMillan, Robert (August 1, 2013)... Java is on the wane, at least according to one outfit that keeps on eye on the ever-changing world of computer programming languages. For more than a decade, it has dominated the Programming Community Index, and is back on top – a snapshot of software developer enthusiasm that looks at things like internet search results to measure how much buzz different languages have.

But lately, Java has been slipping. • on redmonk.com (Stephen O'Grady, January 2015) •. October 25, 2013. Archived from on January 16, 2009. Retrieved April 2, 2015.

Normalized Comparison: 1st C, 2nd Java, 3rd PHP •. Retrieved 2015-04-03. Retrieved 2016-06-19. • Waters, John K. (September 21, 2017).. From the original on September 21, 2017.

• Byous, Jon (c. Sun Developer Network.. Archived from on April 20, 2005.

Retrieved 2005-04-22. • Object-oriented programming. Sun Developer Network. Retrieved 2010-04-30.

• ', Kieron Murphy, JavaWorld.com, 10/04/96 • Kabutz, Heinz;. Retrieved April 29, 2007.

Retrieved October 6, 2012. Tata McGraw-Hill Education. May 24, 2010.

Retrieved 2010-06-09. Retrieved 2014-05-26. Oracle Corporation. Archived from the original on January 31, 2010. Retrieved 2010-08-23.

Oracle has been a leading and substantive supporter of Java since its emergence in 1995 and takes on the new role as steward of Java technology with a relentless commitment to fostering a community of participation and transparency. CS1 maint: BOT: original-url status unknown () •.

Retrieved November 21, 2011. • (April 9, 2010).

On a New Road. Archived from the original on November 5, 2010. Retrieved 2011-11-16. CS1 maint: BOT: original-url status unknown () • Topic, Dalibor..

Archived from on March 10, 2007. Retrieved 2008-02-05. Programmer Interview. Retrieved 2015-01-19. • Niccolai, James (January 23, 2001).. Retrieved 2008-07-09.

• Jelovic, Dejan.. Archived from on February 11, 2008. Retrieved February 15, 2008.

Retrieved 2012-07-12. Retrieved 2014-05-06. Retrieved 2010-08-10.

Retrieved 2017-04-26. Retrieved 2012-06-30. C# for Java Developers.

Retrieved December 10, 2014. The Java™ Tutorials. Retrieved December 10, 2014. The Java™ Tutorials >Getting Started..

Retrieved 2011-04-14. Retrieved 2010-10-14. Retrieved 2010-10-14. • Arnold, Ken.. Archived from the original on October 10, 2007.

Retrieved September 10, 2015. CS1 maint: BOT: original-url status unknown (). More comments to the original article available at earlier archive snapshots like.

• Jelovic, Dejan.. Archived from on February 11, 2008. Retrieved October 17, 2012. • Owens, Sean R.. Archived from on February 20, 2009.

Retrieved 2011-07-04. • Kahan, William. Electrical Engineering & Computer Science, University of California at Berkeley. Retrieved June 4, 2011. • Mullin, Joe.. Law & Disorder. Ars Technica.

Retrieved 2012-05-08. • Mullin, Joe (May 31, 2012).. Ars Technica. Retrieved 2012-06-01. • Rosenblatt, Seth (May 9, 2014).. Retrieved 2014-05-10. • Mullin, Joe (2016-05-26)..

Ars Technica. Retrieved 2016-05-26. Java Documentation. Retrieved December 18, 2014. Java Documentation.

Retrieved December 18, 2014. The Java™ Tutorials. Retrieved December 18, 2014. Oracle Technology Network.

Retrieved December 18, 2014. Oracle Technology Network.

Retrieved December 18, 2014. Oracle Technology Network. Retrieved December 18, 2014.

Oracle Technology Network. Retrieved December 18, 2014. Oracle Technology Network. Retrieved December 18, 2014.

This is a bit of an odd question, but it has been bothering me for a few months now. I have built a JPA-based web application using Wicket + Hibernate (built with Maven), and want to test the DAO layer directly. I created a specific src/test/resources/META-INF/persistence.xml file that I used for testing, but have been running into conflicts with WTP and the like. To get around these issues, I created a separate test project where the unit tests live. Is there a better way to manage unit tests for a JPA project without having duels between persistence files? Addendum: Would other test frameworks (TestNG, for example) make this any easier?

You may want to try. The test works like this: You use mockito to 'implement' EntityManager. Instead of the real code, you use the methods of mockito to say 'if the application calls getReference(), then return this object'. In the background, mockito will create a proxy instance which intercepts the Java method calls and returns the values which you specify. Calls to other methods will return null. Mocking things like createQuery() works the same way but you first need to create a mockup of Query and then use the same approach as in getReference() (return the query mockup).

Since you don't use a real EM, you don't need a real persistence.xml. A much more simple solution would be if you could set some property to change the name of the persistence.xml file but I don't think that this is possible. Some other links that may help: • •. We use dual persistence.xml files for production and test runtimes but it is a classpath related issue only (we use Eclipse but do not rely on WTP plugins heavily). The only difference between the two is that the production version doesn't contain entity definitions. We don't use a mocking framework to test JPA as this wouldn't add any value to our tests.

The tests do run real data access with JPA that talks to PostgreSQL database. Our approach to tests is based on Spring test framework for persistence layer: in-transaction testing. Our application is Spring-based but this approach is equally usable for arbitrary applications that want to take advantage of Spring test classes.

The essence is that each test runs within a single transaction that never commits and at the end (in tearDown) it is automatically rolled back. This solves the problem of data pollution and test dependency in very nice unobtrusive and transparent way. The Spring test framework is flexible to allow multi-transaction testing but these are special cases that constitute not more than 10% of tests. We still use but new for JUnit 4 looks very attractive.

For setting up in-transaction test data we use in-house utility class that constructs business entities. Since it's shared between all tests the overhead to maintain and support it is greatly outweight by the benefits of having standard and reliable way to setup test data. Spring DI helps to make tests concise and self-descriptive but it's not a critical feature.