Meta tags:

Headings (most frequently used words):

edit, navigation, tools, java, native, interface, contents, objectives, design, mapping, types, performance, alternatives, see, also, references, bibliography, external, links, menu, personal, namespaces, views, search, contribute, print, export, languages,

Text of the page (most frequently used words):
the (96), java (61), and (47), #native (47), jni (32), code (22), from (19), interface (18), this (16), for (16), that (13), method (13), can (13), use (12), edit (12), with (12), jvm (12), utf (11), all (10), objects (10), strings (10), wikipedia (9), types (9), are (9), may (8), not (8), platform (8), pointer (8), bits (8), article (7), articles (7), original (7), also (7), when (7), these (7), functions (7), february (6), 2017 (6), applications (6), assembly (6), language (6), programs (6), library (6), access (6), such (6), signed (6), page (5), was (5), research (5), used (5), string (5), methods (5), arrays (5), signature (5), type (5), jnienv (5), about (4), additional (4), using (4), links (4), learn (4), references (4), retrieved (4), specification (4), api (4), calls (4), data (4), machine (4), array (4), function (4), performance (4), any (4), mapping (4), char (4), class (4), unsigned (4), which (4), standard (4), framework (4), only (4), thread (4), env (4), application (4), file (3), changes (3), help (3), navigation (3), talk (3), issues (3), needing (3), https (3), org (3), exception (3), programmer (3), guide (3), invocation (3), 2007 (3), software (3), see (3), without (3), than (3), environment (3), could (3), direct (3), implementation (3), calling (3), called (3), way (3), call (3), itself (3), but (3), following (3), accessing (3), passed (3), then (3), int (3), example (3), uses (3), void (3), short (3), encoding (3), modified (3), side (3), provide (3), other (3), nativestring (3), javastring (3), design (3), same (3), written (3), programming (3), how (3), remove (3), template (3), please (3), view (2), contact (2), privacy (2), policy (2), available (2), under (2), terms (2), you (2), non (2), 2021 (2), languages (2), link (2), pages (2), upload (2), what (2), here (2), tools (2), community (2), current (2), contents (2), search (2), create (2), categories (2), contain (2), multiple (2), covered (2), wikiproject (2), wikify (2), cleanup (2), java_native_interface (2), handling (2), oracle (2), external (2), 1st (2), isbn (2), prentice (2), hall (2), bibliography (2), makes (2), slow (2), sun (2), docs (2), net (2), 2006 (2), archived (2), overview (2), provides (2), easy (2), libraries (2), rni (2), less (2), instead (2), generated (2), files (2), classes (2), necessary (2), microsoft (2), virtual (2), had (2), similar (2), addition (2), existing (2), windows (2), however (2), visual (2), alternatives (2), have (2), encoded (2), object (2), needs (2), its (2), something (2), specified (2), copied (2), back (2), compiled (2), one (2), where (2), between (2), different (2), would (2), jstring (2), jint (2), lang (2), long (2), getstringutfchars (2), releasestringutfchars (2), valid (2), null (2), many (2), into (2), endian (2), architectures (2), platforms (2), seh (2), capture (2), handle (2), situations (2), responsibility (2), does (2), memory (2), resources (2), explicitly (2), argument (2), each (2), mapped (2), within (2), remains (2), must (2), attached (2), running (2), has (2), declared (2), obj (2), converting (2), jobject (2), separate (2), allows (2), possible (2), awt (2), write (2), operating (2), system (2), inspect (2), enables (2), specific (2), accessible (2), functionality (2), objectives (2), message (2), lead (2), sources (2), citations (2), improve (2), jump (2), web (2), sep (2), cookie, statement, statistics, developers, mobile, disclaimers, text, apply, site, agree, registered, trademark, profit, organization, wikimedia, foundation, inc, creative, commons, attribution, sharealike, license, last, edited, october, utc, tiếng, việt, українська, русский, português, polski, 日本語, nederlands, italiano, 한국어, français, español, eesti, deutsch, čeština, printable, version, download, pdf, print, export, wikidata, item, cite, information, permanent, special, related, recent, portal, contribute, donate, random, events, main, more, history, read, views, english, namespaces, log, account, contributions, logged, personal, menu, hidden, maintenance, introduction, index, php, title, oldid, 1052615393, modern, wrapper, xcode, apple, liang, sheng, june, 1999, 320, 201, 32577, gordon, rob, march, 1998, 498, 679895, essential, stack, overflow, structures, microsystems, com, javase, specs, html, launch, 2008, invoking, 2018, swig, services, gluegen, giws, developed, shared, jna, clumsy, because, bookkeeping, needed, accessed, directly, facilitate, tool, header, similarly, easier, intermediate, proprietary, mechanism, wasn, aware, limited, longer, maintained, litigation, raw, length, creating, require, copy, make, callback, will, likely, making, own, fields, requires, signatures, queried, both, error, prone, reflection, later, cost, linear, size, inlined, nor, already, jit, expensive, especially, repeatedly, incurs, considerable, overhead, loss, certain, circumstances, interchangeable, normally, vice, versa, required, crash, typecasting, mean, uniquely, name, refers, prefixing, means, finally, ljava, fully, qualified, jdouble, double, jfloat, float, jlong, int64_t, int32_t, jshort, int16_t, jchar, uint16_t, jbyte, int8_t, jboolean, uint8_t, description, table, shows, newstringutf, getstringutflength, getstringutfregion, inputs, really, character, 0000, codepoints, greater, equal, 10000, those, represented, differently, actually, incorrectly, treat, returned, should, newstring, getstringlength, getstringchars, releasestringchars, getstringregion, getstringcritical, releasestringcritical, 16le, little, 16be, big, conversion, routine, surrogate, pairs, basic, multilingual, plane, linux, solaris, registers, signal, handler, intercept, signals, intended, allow, better, inter, operate, employed, wrap, try, catch, blocks, cpu, fpu, interrupts, violations, divide, zero, operations, before, interrupt, propagated, likelihood, resulting, unhandled, structured, chain, automatic, garbage, collection, allocated, executing, consequently, assumes, releasing, acquires, allowing, interaction, stored, threads, first, attach, themselves, obtain, once, works, like, regular, until, detach, detachcurrentthread, attachcurrentthread, compound, convert, reference, inside, been, structure, contains, includes, interact, work, instantiating, throwing, exceptions, etc, basically, anything, done, albeit, considerably, ease, const, java_classname_methodname, jnicall, jniexport, extern, implemented, cpp, slightly, simpler, invokes, passes, arguments, converts, even, going, through, bridge, draw, process, almost, just, few, since, j2se, canvas, relies, loses, portability, offers, partial, workaround, detect, load, correct, runtime, applets, invoke, lets, perform, tasks, created, programmers, cannot, entirely, support, features, program, modify, another, depend, developer, user, sound, capabilities, including, sensitive, implementations, safe, independent, manner, hardware, foreign, discuss, consider, expanding, important, aspects, too, adequately, key, points, summarize, section, unsourced, material, challenged, removed, jstor, scholar, books, newspapers, news, find, adding, reliable, verification, messages, redirects, disambiguation, free, encyclopedia, wayback, http, archive, 20221004154855, wiki, timestamps, fail, success, 2023, 2022, nov, oct, dec, 2003, 2026, 532, captures,

Text of the page (random words):
java native interface wikipedia 532 captures 09 dec 2003 24 sep 2026 sep oct nov 04 2021 2022 2023 success fail about this capture timestamps the wayback machine http web archive org web 20221004154855 https en wikipedia org wiki java_native_interface java native interface from wikipedia the free encyclopedia jump to navigation jump to search jni redirects here for other uses see jni disambiguation this article has multiple issues please help improve it or discuss these issues on the talk page learn how and when to remove these template messages this article needs additional citations for verification please help improve this article by adding citations to reliable sources unsourced material may be challenged and removed find sources java native interface news newspapers books scholar jstor february 2017 learn how and when to remove this template message this article s lead section may be too short to adequately summarize the key points please consider expanding the lead to provide an accessible overview of all important aspects of the article february 2017 learn how and when to remove this template message in software design the java native interface jni is a foreign function interface programming framework that enables java code running in a java virtual machine jvm to call and be called by 1 native applications programs specific to a hardware and operating system platform and libraries written in other languages such as c c and assembly contents 1 objectives 2 design 3 mapping types 4 performance 5 alternatives 6 see also 7 references 8 bibliography 9 external links objectives edit jni enables programmers to write native methods to handle situations when an application cannot be written entirely in the java programming language e g when the standard java class library does not support the platform specific features or program library it is also used to modify an existing application written in another programming language to be accessible to java applications many of the standard library classes depend on jni to provide functionality to the developer and the user e g file i o and sound capabilities including performance and platform sensitive api implementations in the standard library allows all java applications to access this functionality in a safe and platform independent manner the jni framework lets a native method use java objects in the same way that java code uses these objects a native method can create java objects and then inspect and use these objects to perform its tasks a native method can also inspect and use objects created by java application code only applications and signed applets can invoke jni an application that relies on jni loses the platform portability java offers a partial workaround is to write a separate implementation of jni code for each platform and have java detect the operating system and load the correct one at runtime not only can native code interface with java it can also draw on a java canvas which is possible with the java awt native interface the process is almost the same with just a few changes the java awt native interface is only available since j2se 1 3 jni also allows direct access to assembly code without even going through a c bridge 2 accessing java applications from assembly is possible in the same way 3 design edit in the jni framework native functions are implemented in separate c or cpp files c provides a slightly simpler interface with jni when the jvm invokes the function it passes a jnienv pointer a jobject pointer and any java arguments declared by the java method for example the following converts a java string to a native string extern c jniexport void jnicall java_classname_methodname jnienv env jobject obj jstring javastring const char nativestring env getstringutfchars javastring 0 do something with the nativestring env releasestringutfchars javastring nativestring the env pointer is a structure that contains the interface to the jvm it includes all of the functions necessary to interact with the jvm and to work with java objects example jni functions are converting native arrays to from java arrays converting native strings to from java strings instantiating objects throwing exceptions etc basically anything that java code can do can be done using jnienv albeit with considerably less ease the argument obj is a reference to the java object inside which this native method has been declared native data types can be mapped to from java data types for compound types such as objects arrays and strings the native code must explicitly convert the data by calling methods in the jnienv a jni environment pointer jnienv is passed as an argument for each native function mapped to a java method allowing for interaction with the jni environment within the native method this jni interface pointer can be stored but remains valid only in the current thread other threads must first call attachcurrentthread to attach themselves to the vm and obtain a jni interface pointer once attached a native thread works like a regular java thread running within a native method the native thread remains attached to the vm until it calls detachcurrentthread to detach itself 4 the jni framework does not provide any automatic garbage collection for non jvm memory resources allocated by code executing on the native side consequently native side code such as assembly language assumes the responsibility for explicitly releasing any such memory resources that the native code acquires on linux and solaris platforms if the native code registers itself as a signal handler it could intercept signals intended for the jvm a chain of responsibility can be used to allow native code to better inter operate with the jvm on windows platforms structured exception handling seh may be employed to wrap native code in seh try catch blocks so as to capture machine cpu fpu generated software interrupts such as null pointer access violations and divide by zero operations and to handle these situations before the interrupt is propagated back up into the jvm i e java side code in all likelihood resulting in an unhandled exception original research the encoding used for the newstringutf getstringutflength getstringutfchars releasestringutfchars and getstringutfregion functions is modified utf 8 5 which is not valid utf 8 for all inputs but a different encoding really the null character u 0000 and codepoints not on the basic multilingual plane greater than or equal to u 10000 i e those represented as surrogate pairs in utf 16 are encoded differently in modified utf 8 many programs actually use these functions incorrectly and treat the utf 8 strings returned or passed into the functions as standard utf 8 strings instead of modified utf 8 strings programs should use the newstring getstringlength getstringchars releasestringchars getstringregion getstringcritical and releasestringcritical functions which use utf 16le encoding on little endian architectures and utf 16be on big endian architectures and then use a utf 16 to utf 8 conversion routine original research mapping types edit the following table shows the mapping of types between java jni and native code c type java language type description type signature unsigned char uint8_t jboolean unsigned 8 bits z signed char int8_t jbyte signed 8 bits b unsigned short uint16_t jchar unsigned 16 bits c short int16_t jshort signed 16 bits s int int32_t jint signed 32 bits i long long int64_t jlong signed 64 bits j float jfloat 32 bits f double jdouble 64 bits d void v in addition the signature l fully qualified class would mean the class uniquely specified by that name e g the signature ljava lang string refers to the class java lang string also prefixing to the signature makes the array of that type for example i means the int array type finally a void signature uses the v code these types are interchangeable one can use jint where you normally use an int and vice versa without any typecasting required however mapping between java strings and arrays to native strings and arrays is different if a jstring is used where a char would be the code could crash the jvm original research performance edit jni incurs considerable overhead and performance loss under certain circumstances 6 function calls to jni methods are expensive especially when calling a method repeatedly native methods are not inlined by the jvm nor can the method be jit compiled as the method is already compiled a java array may be copied for access in native code and later copied back the cost can be linear in the size of the array if the method is passed an object or needs to make a callback then the native method will likely be making its own calls to the jvm accessing java fields methods and types from the native code requires something similar to reflection signatures are specified in strings and queried from the jvm this is both slow and error prone java strings are objects have length and are encoded accessing or creating a string may require an o n copy alternatives edit microsoft s proprietary implementation of a java virtual machine visual j had a similar mechanism for calling native code from java called the raw native interface rni in addition it had an easy way to call existing native code that wasn t itself aware of java such as but not limited to the windows api called j direct however following the sun microsoft litigation about this implementation visual j is no longer maintained rni was less clumsy to use than jni because no bookkeeping with a java environment pointer was needed instead all java objects could be accessed directly to facilitate this a tool was used that generated header files from java classes similarly j direct was easier to use than using the necessary intermediate native library and jni java native access jna is a community developed library that provides java programs easy access to native shared libraries without using jni see also edit giws software gluegen platform invocation services swig references edit java native interface overview the java native interface programmer s guide and specification retrieved 2018 12 27 invoking assembly language programs from java java net 2006 10 19 archived from the original on 2008 03 30 retrieved 2007 10 06 launch java applications from assembly language programs java net 2006 10 19 archived from the original on 2007 10 11 retrieved 2007 10 04 the invocation api sun microsystems https docs oracle com en java javase 11 docs specs jni invocation html jni types and data structures java what makes jni calls slow stack overflow bibliography edit gordon rob march 1998 essential jni java native interface 1st ed prentice hall p 498 isbn 0 13 679895 0 liang sheng june 20 1999 java tm native interface programmer s guide and specification 1st ed prentice hall p 320 isbn 0 201 32577 2 external links edit oracle s jni 6 0 api specification java native interface programmer s guide and specification jni in xcode from apple exception handling in jni java link modern c 17 wrapper for jni retrieved from https en wikipedia org w index php title java_native_interface oldid 1052615393 categories java platform hidden categories articles needing additional references from february 2017 all articles needing additional references wikipedia introduction cleanup from february 2017 all pages needing cleanup articles covered by wikiproject wikify from february 2017 all articles covered by wikiproject wikify articles with multiple maintenance issues all articles that may contain original research articles that may contain original research from february 2017 navigation menu personal tools not logged in talk contributions create account log in namespaces article talk english views read edit view history more search navigation main page contents current events random article about wikipedia contact us donate contribute help learn to edit community portal recent changes upload file tools what links here related changes upload file special pages permanent link page information cite this page wikidata item print export download as pdf printable version languages čeština deutsch eesti español français 한국어 italiano nederlands 日本語 polski português русский українська tiếng việt 中文 edit links this page was last edited on 30 october 2021 at 04 56 utc text is available under the creative commons attribution sharealike license 3 0 additional terms may apply by using this site you agree to the terms of use and privacy policy wikipedia is a registered trademark of the wikimedia foundation inc a non profit organization privacy policy about wikipedia disclaimers contact wikipedia mobile view developers statistics cookie statement