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Java bytecode

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Java bytecode is the instruction set of the <a href="Java_virtual_machine" title="Java virtual machine">Java virtual machine</a> (JVM), the language to which <a href="Java_(programming_language)" title="Java (programming language)">Java</a> and other JVM-compatible <a href="Source_code" title="Source code">source code</a> is <a href="Compiler" title="Compiler">compiled</a>.<a href="#cite_note-oracle_jvm_spec-1">[1]</a> Each instruction is represented by a single <a href="Byte" title="Byte">byte</a>, hence the name <a href="Bytecode" title="Bytecode">bytecode</a>, making it a compact form of <a href="Data" title="Data">data</a>.<a href="#cite_note-JVM_Book-2">[2]</a>

Due to the nature of bytecode, a Java bytecode <a href="Computer_program" title="Computer program">program</a> is runnable on any machine with a compatible JVM, without the lengthy process of compiling from source code.

Java bytecode is used at <a href="Runtime_(program_lifecycle_phase)" class="mw-redirect" title="Runtime (program lifecycle phase)">runtime</a> either <a href="Interpreter_(computing)" title="Interpreter (computing)">interpreted</a> by a JVM or compiled to machine code via <a href="Just-in-time_compilation" title="Just-in-time compilation">just-in-time</a> (JIT) compilation and run as a native application.

As Java bytecode is designed for a cross-platform compatibility and security, a Java bytecode application tends to run consistently across various <a href="Computer_hardware" title="Computer hardware">hardware</a> and <a href="Software" title="Software">software</a> configurations.<a href="#cite_note-3">[3]</a>

<div class="mw-heading mw-heading2"><h2 id="Relation_to_Java">Relation to Java</h2></div>

In general, a Java <a href="Programmer" title="Programmer">programmer</a> does not need to understand Java bytecode or even be aware of it. However, as suggested in the <a href="IBM" title="IBM">IBM</a> developerWorks journal, "Understanding bytecode and what bytecode is likely to be generated by a <a href="Java_compiler" title="Java compiler">Java compiler</a> helps the Java programmer in the same way that knowledge of <a href="Assembly_language" title="Assembly language">assembly</a> helps the <a href="C_(programming_language)" title="C (programming language)">C</a> or <a href="C%2B%2B" title="C++">C++</a> programmer."<a href="#cite_note-4">[4]</a>

<div class="mw-heading mw-heading2"><h2 id="Instruction_set_architecture">Instruction set architecture</h2></div>

The bytecode comprises various instruction types, including data manipulation, control transfer, object creation and manipulation, and method invocation, all integral to Java's object-oriented programming model.<a href="#cite_note-oracle_jvm_spec-1">[1]</a>

The JVM is both a <a href="Stack_machine" title="Stack machine">stack machine</a> and a <a href="Register_machine" title="Register machine">register machine</a>. Each <a href="Call_stack#STACK-FRAME" title="Call stack">frame</a> for a method call has an "operand stack" and an array of "local variables".<a href="#cite_note-jvm-5">[5]</a>: 2.6 <a href="#cite_note-JVM_Book-2">[2]</a> The operand stack is used for passing operands to computations and for receiving the return value of a called method, while local variables serve the same purpose as <a href="Processor_register" title="Processor register">registers</a> and are also used to pass method arguments. The maximum size of the operand stack and local variable array, computed by the compiler, is part of the attributes of each method.<a href="#cite_note-jvm-5">[5]</a>: 4.7.3 Each can be independently sized from 0 to 65535 values, where each value is 32 bits. <code class="mw-highlight mw-highlight-lang-java mw-content-ltr" style="" dir="ltr">long</code> and <code class="mw-highlight mw-highlight-lang-java mw-content-ltr" style="" dir="ltr">double</code> types, which are 64 bits, take up two consecutive local variables<a href="#cite_note-jvm-5">[5]</a>: 2.6.1 (which need not be 64-bit aligned in the local variables array) or one value in the operand stack (but are counted as two units in the depth of the stack).<a href="#cite_note-jvm-5">[5]</a>: 2.6.2

<div class="mw-heading mw-heading3"><h3 id="Instruction_set">Instruction set</h3></div>

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</style><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="List_of_Java_bytecode_instructions" title="List of Java bytecode instructions">List of Java bytecode instructions</a></div>

Each <a href="Bytecode" title="Bytecode">bytecode</a> is composed of one byte that represents the <a href="Opcode" title="Opcode">opcode</a>, along with zero or more bytes for operands.<a href="#cite_note-jvm-5">[5]</a>: 2.11

Of the 256 possible byte-long <a href="Opcode" title="Opcode">opcodes</a>, as of 2015, 202 are in use (~79%), 51 are reserved for future use (~20%), and 3 instructions (~1%) are permanently reserved for JVM implementations to use.<a href="#cite_note-jvm-5">[5]</a>: 6.2 Two of these (<code>impdep1</code> and <code>impdep2</code>) are to provide traps for implementation-specific software and hardware, respectively. The third is used for debuggers to implement breakpoints.

Instructions fall into a number of broad groups:

<ul><li>Load and store (e.g. <code>aload_0</code>, <code>istore</code>)</li>

<li>Arithmetic and logic (e.g. <code>ladd</code>, <code>fcmpl</code>)</li>

<li>Type conversion (e.g. <code>i2b</code>, <code>d2i</code>)</li>

<li>Object creation and manipulation (<code>new</code>, <code>putfield</code>)</li>

<li>Operand stack management (e.g. <code>swap</code>, <code>dup2</code>)</li>

<li>Control transfer (e.g. <code>ifeq</code>, <code>goto</code>)</li>

<li>Method invocation and return (e.g. <code>invokespecial</code>, <code>areturn</code>)</li></ul>

There are also a few instructions for a number of more specialized tasks such as exception throwing, synchronization, etc.

Many instructions have prefixes and/or suffixes referring to the types of operands they operate on.<a href="#cite_note-jvm-5">[5]</a>: 2.11.1 These are as follows:

<th>Prefix/suffix</th>

<th>Operand type

</th></tr>

<tr>

<td>integer

</td></tr>

<tr>

<td>long

</td></tr>

<tr>

<td>short

</td></tr>

<tr>

<td>byte

</td></tr>

<tr>

<td>character

</td></tr>

<tr>

<td>float

</td></tr>

<tr>

<td>double

</td></tr>

<tr>

<td>reference

</td></tr></tbody></table>

For example, <code>iadd</code> will add two integers, while <code>dadd</code> will add two doubles. The <code>const</code>, <code>load</code>, and <code>store</code> instructions may also take a suffix of the form <code>_n</code>, where n is a number from 0–3 for <code>load</code> and <code>store</code>. The maximum n for <code>const</code> differs by type.

The <code>const</code> instructions push a value of the specified type onto the stack. For example, <code>iconst_5</code> will push an integer (32 bit value) with the value 5 onto the stack, while <code>dconst_1</code> will push a double (64 bit floating point value) with the value 1 onto the stack. There is also an <code>aconst_null</code>, which pushes a <code class="mw-highlight mw-highlight-lang-java mw-content-ltr" style="" dir="ltr">null</code> reference. The n for the <code>load</code> and <code>store</code> instructions specifies the index in the local variable array to load from or store to. The <code>aload_0</code> instruction pushes the object in local variable 0 onto the stack (this is usually the <code><a href="This_(computer_programming)" title="This (computer programming)">this</a></code> object). <code>istore_1</code> stores the integer on the top of the stack into local variable 1. For local variables beyond 3 the suffix is dropped and operands must be used.

<div class="mw-heading mw-heading2"><h2 id="Example">Example</h2></div>

Consider the following Java code:

<div class="mw-highlight mw-highlight-lang-java mw-content-ltr" dir="ltr"><pre>outer:

for (int i = 2; i < 1000; i++) {

for (int j = 2; j < i; j++) {

if (i % j == 0)

continue outer;

}

System.out.println(i);

}

</pre></div>

A Java compiler might translate the Java code above into bytecode as follows, assuming the above was put in a method:

<div class="mw-highlight mw-highlight-lang-jasmin mw-content-ltr" dir="ltr"><pre>0: iconst_2

1: istore_1

2: iload_1

3: sipush 1000

6: if_icmpge 44

9: iconst_2

10: istore_2

11: iload_2

12: iload_1

13: if_icmpge 31

16: iload_1

17: iload_2

18: irem

19: ifne 25

22: goto 38

25: iinc 2, 1

28: goto 11

31: getstatic #84; // Field java/lang/System.out:Ljava/io/PrintStream;

34: iload_1

35: invokevirtual #85; // Method java/io/PrintStream.println:(I)V

38: iinc 1, 1

41: goto 2

44: return

</pre></div>

<div class="mw-heading mw-heading2"><h2 id="Generation">Generation</h2></div>

<div role="note" class="hatnote navigation-not-searchable">Further information: <a href="List_of_JVM_languages" title="List of JVM languages">List of JVM languages</a></div>

The most common language targeting <a href="Java_virtual_machine" title="Java virtual machine">Java virtual machine</a> by producing Java bytecode is Java. Originally only one compiler existed, the <a href="Javac" title="Javac">javac</a> compiler from <a href="Sun_Microsystems" title="Sun Microsystems">Sun Microsystems</a>, which compiles <a href="Java_source_code" class="mw-redirect" title="Java source code">Java source code</a> to Java bytecode; but because all the specifications for Java bytecode are now available, other parties have supplied compilers that produce Java bytecode. Examples of other compilers include:

<ul><li>Eclipse compiler for Java (ECJ)</li>

<li><a href="Jikes" title="Jikes">Jikes</a>, compiles from Java to Java bytecode (developed by <a href="IBM" title="IBM">IBM</a>, implemented in <a href="C%2B%2B" title="C++">C++</a>)</li>

<li>Espresso, compiles from Java to Java bytecode (Java 1.0 only)</li>

<li><a href="GNU_Compiler_for_Java" title="GNU Compiler for Java">GNU Compiler for Java</a> (GCJ), compiles from Java to Java bytecode; it can also compile to native <a href="Machine_code" title="Machine code">machine code</a> and was part of the <a href="GNU_Compiler_Collection" title="GNU Compiler Collection">GNU Compiler Collection</a> (GCC) up until version 6.</li></ul>

Some projects provide Java assemblers to enable writing Java bytecode by hand. Assembly code may be also generated by machine, for example by a compiler targeting a <a href="Java_virtual_machine" title="Java virtual machine">Java virtual machine</a>. Notable Java assemblers include:

<ul><li>Jasmin, takes text descriptions for Java classes, written in a simple assembly-like syntax using Java virtual machine instruction set and generates a Java class file<a href="#cite_note-6">[6]</a></li>

<li>Jamaica, a <a href="Macro_(computer_science)" title="Macro (computer science)">macro</a> <a href="Assembly_language" title="Assembly language">assembly language</a> for the <a href="Java_virtual_machine" title="Java virtual machine">Java virtual machine</a>. Java syntax is used for class or interface definition. Method bodies are specified using bytecode instructions.<a href="#cite_note-7">[7]</a></li>

<li>Krakatau Bytecode Tools, currently contains three tools: a decompiler and disassembler for Java classfiles and an assembler to create classfiles.<a href="#cite_note-8">[8]</a></li>

<li>Lilac, an assembler and disassembler for the <a href="Java_virtual_machine" title="Java virtual machine">Java virtual machine</a>.<a href="#cite_note-9">[9]</a></li></ul>

Others have developed compilers, for different programming languages, to target the Java virtual machine, such as:

<ul><li><a href="ColdFusion" class="mw-redirect" title="ColdFusion">ColdFusion</a></li>

<li><a href="JRuby" title="JRuby">JRuby</a> and <a href="Jython" title="Jython">Jython</a>, two <a href="Scripting_language" title="Scripting language">scripting languages</a> based on <a href="Ruby_(programming_language)" title="Ruby (programming language)">Ruby</a> and <a href="Python_(programming_language)" title="Python (programming language)">Python</a></li>

<li><a href="Groovy_(programming_language)" class="mw-redirect" title="Groovy (programming language)">Apache Groovy</a>, optionally typed and dynamic general-purpose language, with static-typing and static compilation capabilities</li>

<li><a href="Scala_(programming_language)" title="Scala (programming language)">Scala</a>, a type-safe general-purpose programming language supporting object-oriented and functional programming</li>

<li><a href="JGNAT" class="mw-redirect" title="JGNAT">JGNAT</a> and AppletMagic, compile from the language <a href="Ada_(programming_language)" title="Ada (programming language)">Ada</a> to Java bytecode</li>

<li><a href="Java_virtual_machine#C_to_bytecode_compilers" title="Java virtual machine">C to Java byte-code compilers</a> </li>

<li><a href="Clojure" title="Clojure">Clojure</a>, a functional, immutable, general-purpose programming language in the <a href="Lisp_(programming_language)" title="Lisp (programming language)">Lisp</a> family with a strong emphasis on concurrency</li>

<li><a href="Kawa_(Scheme_implementation)" title="Kawa (Scheme implementation)">Kawa</a>, an implementation of the <a href="Scheme_(programming_language)" title="Scheme (programming language)">Scheme</a> programming language, also a dialect of <a href="Lisp_(programming_language)" title="Lisp (programming language)">Lisp</a>.</li>

<li>MIDletPascal</li>

<li><a href="JavaFX_Script" title="JavaFX Script">JavaFX Script</a> code is compiled to Java bytecode</li>

<li><a href="Kotlin_(programming_language)" title="Kotlin (programming language)">Kotlin</a>, a statically-typed general-purpose programming language with type inference</li>

<li><a href="Object_Pascal" title="Object Pascal">Object Pascal</a> source code is compiled to Java bytecode using the <a href="Free_Pascal" title="Free Pascal">Free Pascal</a> 3.0+ compiler.<a href="#cite_note-10">[10]</a><a href="#cite_note-11">[11]</a></li></ul>

<div class="mw-heading mw-heading2"><h2 id="Execution">Execution</h2></div>

<div role="note" class="hatnote navigation-not-searchable">Further information: <a href="Java_virtual_machine" title="Java virtual machine">Java virtual machine</a></div>

There are several Java virtual machines available today to execute Java bytecode, both free and commercial products. If executing bytecode in a virtual machine is undesirable, a developer can also compile Java source code or bytecode directly to native machine code with tools such as the <a href="GNU_Compiler_for_Java" title="GNU Compiler for Java">GNU Compiler for Java</a> (GCJ). Some processors can execute Java bytecode natively. Such processors are termed <a href="Java_processor" title="Java processor">Java processors</a>.

<div class="mw-heading mw-heading2"><h2 id="Support_for_dynamic_languages">Support for dynamic languages</h2></div>

<div role="note" class="hatnote navigation-not-searchable">Further information: <a href="List_of_JVM_languages" title="List of JVM languages">List of JVM languages</a></div>

The <a href="Java_virtual_machine" title="Java virtual machine">Java virtual machine</a> provides some support for <a href="Type_system#Dynamic_typing" title="Type system">dynamically typed languages</a>. Most of the extant JVM instruction set is <a href="Type_system#Static_typing" title="Type system">statically typed</a> - in the sense that method calls have their signatures type-checked at <a href="Compile_time" title="Compile time">compile time</a>, without a mechanism to defer this decision to <a href="Run_time_(program_lifecycle_phase)" class="mw-redirect" title="Run time (program lifecycle phase)">run time</a>, or to choose the method dispatch by an alternative approach.<a href="#cite_note-12">[12]</a>

<a href="Java_Community_Process" title="Java Community Process">JSR</a> 292 (Supporting Dynamically Typed Languages on the Java Platform)<a href="#cite_note-13">[13]</a> added a new <code>invokedynamic</code> instruction at the JVM level, to allow method invocation relying on dynamic <a href="Type_system#Type_checking" title="Type system">type checking</a> (instead of the extant statically type-checked <code>invokevirtual</code> instruction). The <a href="Da_Vinci_Machine" title="Da Vinci Machine">Da Vinci Machine</a> is a prototype virtual machine implementation that hosts JVM extensions aimed at supporting dynamic languages. All JVMs supporting <a href="Java_Platform%2C_Standard_Edition" title="Java Platform, Standard Edition">JSE</a> 7 also include the <code>invokedynamic</code> opcode.

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<ul><li><a href="Byte_Code_Engineering_Library" title="Byte Code Engineering Library">Byte Code Engineering Library</a></li>

<li><a href="Common_Intermediate_Language" title="Common Intermediate Language">Common Intermediate Language</a> (CIL), Microsoft's rival to Java bytecode</li>

<li><a href="Java_backporting_tools" class="mw-redirect" title="Java backporting tools">Java backporting tools</a></li>

<li><a href="Java_class_file" title="Java class file">Java class file</a></li>

<li><a href="Java_virtual_machine" title="Java virtual machine">Java virtual machine</a></li>

<li><a href="JStik" title="JStik">JStik</a></li>

<li><a href="ObjectWeb_ASM" title="ObjectWeb ASM">ObjectWeb ASM</a></li>

<li><a href="List_of_Java_bytecode_instructions" title="List of Java bytecode instructions">List of Java bytecode instructions</a></li>

<li><a href="List_of_JVM_languages" title="List of JVM languages">List of JVM languages</a></li></ul>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

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</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://docs.oracle.com/javase/specs/jvms/se8/html/">"Java Virtual Machine Specification"</a>. Oracle. Retrieved 14 November 2023.</cite>

</li>

<li id="cite_note-JVM_Book-2">^ <a href="#cite_ref-JVM_Book_2-0">a</a> <a href="#cite_ref-JVM_Book_2-1">b</a> <cite id="CITEREFLindholm2015" class="citation book cs1">Lindholm, Tim (2015). The Java Virtual Machine Specification. Oracle. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-0133905908</bdi>.</cite>

</li>

<li id="cite_note-3"><a href="#cite_ref-3">^</a> <cite id="CITEREFArnold1996" class="citation journal cs1">Arnold, Ken (1996). "The Java Programming Language". Sun Microsystems. 1 (1): 30–40.</cite>

</li>

<li id="cite_note-4"><a href="#cite_ref-4">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://developer.ibm.com/languages/java/">"IBM Developer"</a>. developer.ibm.com. Retrieved 20 February 2006.</cite>

</li>

<li id="cite_note-jvm-5">^ <a href="#cite_ref-jvm_5-0">a</a> <a href="#cite_ref-jvm_5-1">b</a> <a href="#cite_ref-jvm_5-2">c</a> <a href="#cite_ref-jvm_5-3">d</a> <a href="#cite_ref-jvm_5-4">e</a> <a href="#cite_ref-jvm_5-5">f</a> <a href="#cite_ref-jvm_5-6">g</a> <cite id="CITEREFLindholmYellinBrachaBuckley2015" class="citation book cs1">Lindholm, Tim; Yellin, Frank; Bracha, Gilad; Buckley, Alex (13 February 2015). <a rel="nofollow" class="external text" href="http://docs.oracle.com/javase/specs/jvms/se8/html/">The Java Virtual Machine Specification</a> (Java SE 8 ed.).</cite>

</li>

<li id="cite_note-6"><a href="#cite_ref-6">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://jasmin.sourceforge.net/">"Jasmin Home Page"</a>. jasmin.sourceforge.net. Retrieved 2 June 2024.</cite>

</li>

<li id="cite_note-7"><a href="#cite_ref-7">^</a> <cite id="CITEREFHuang" class="citation web cs1">Huang, James Jianbo. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20231114000632/https://www.infoworld.com/article/2072355/learn-to-speak-jamaican.html">"Jamaica: The Java virtual machine (JVM) macro assembler"</a>. JavaWorld. Archived from <a rel="nofollow" class="external text" href="https://www.javaworld.com/article/2072355/core-java/learn-to-speak-jamaican.html">the original</a> on 14 November 2023. Retrieved 2 June 2024.</cite>

</li>

<li id="cite_note-8"><a href="#cite_ref-8">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://github.com/Storyyeller/Krakatau">"Storyyeller/Krakatau"</a>. 1 June 2024. Retrieved 2 June 2024 – via GitHub.</cite>

</li>

<li id="cite_note-9"><a href="#cite_ref-9">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://lilac.sourceforge.net/">"Lilac - a Java assembler"</a>. lilac.sourceforge.net. Retrieved 2 June 2024.</cite>

</li>

<li id="cite_note-10"><a href="#cite_ref-10">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://wiki.freepascal.org/FPC_New_Features_3.0">"FPC New Features 3.0.0 - Free Pascal wiki"</a>. wiki.freepascal.org. Retrieved 2 June 2024.</cite>

</li>

<li id="cite_note-11"><a href="#cite_ref-11">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://wiki.freepascal.org/FPC_JVM">"FPC JVM - Free Pascal wiki"</a>. wiki.freepascal.org. Retrieved 2 June 2024.</cite>

</li>

<li id="cite_note-12"><a href="#cite_ref-12">^</a> <cite id="CITEREFNutter2007" class="citation web cs1">Nutter, Charles (3 January 2007). <a rel="nofollow" class="external text" href="http://headius.blogspot.com/2007/01/invokedynamic-actually-useful.html">"InvokeDynamic: Actually Useful?"</a>. Retrieved 25 January 2008.</cite>

</li>

<li id="cite_note-13"><a href="#cite_ref-13">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.jcp.org/en/jsr/detail?id=292">"The Java Community Process(SM) Program - JSRs: Java Specification Requests - detail JSR# 292"</a>. www.jcp.org. Retrieved 2 June 2024.</cite>

</li>

</ol></div>

<div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div>

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<div class="side-box-text plainlist">The Wikibook <a href="https://en.wikibooks.org/wiki/Java_Programming" class="extiw external" title="wikibooks:Java Programming">Java Programming</a> has a page on the topic of: <a href="https://en.wikibooks.org/wiki/Java_Programming/Byte_Code" class="extiw external" title="wikibooks:Java Programming/Byte Code">Java bytecode</a></div></div>

</div>

<ul><li><a rel="nofollow" class="external text" href="http://docs.oracle.com/javase/specs/jvms/se8/html/">Oracle's Java Virtual Machine Specification</a></li>

<li><a rel="nofollow" class="external text" href="http://www.is-research.de/info/vmlanguages/">Programming Languages for the Java Virtual Machine</a></li>

<li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20130618025348/http://www.drgarbage.com/bytecode-visualizer.html">Bytecode Visualizer – bytecode viewer and debugger (free Eclipse plugin)</a></li>

<li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20090809232522/http://www.adaptj.com/main/stacktrace">AdaptJ StackTrace – bytecode level debugging with a full control of the stack, the local variables, and the execution flow</a></li>

<li><a rel="nofollow" class="external text" href="http://lulachronicles.blogspot.com">Java Class Unpacker – plugin for Total Commander, it lets open class files as compressed archives and see fields and methods as files. The bytecode can be viewed as text using F3</a></li></ul>

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</style><div id="Java_(software_platform)419" style="font-size:114%;margin:0 4em"><a href="Java_(software_platform)" title="Java (software platform)">Java (software platform)</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Platforms</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="Java_Platform%2C_Micro_Edition" title="Java Platform, Micro Edition">Java ME</a> (Micro)</li>

<li><a href="Java_Platform%2C_Standard_Edition" title="Java Platform, Standard Edition">Java SE</a> (Standard)</li>

<li><a href="Jakarta_EE" title="Jakarta EE">Jakarta EE</a> (Enterprise)</li>

<li><a href="Android_software_development#SDK" title="Android software development">Android SDK</a></li>

<li><a href="GraalVM" title="GraalVM">GraalVM</a></li></ul>

</div></td><td class="noviewer navbox-image" rowspan="5" style="width:1px;padding:0 0 0 2px"><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Technologies</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Oracle</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Squawk_virtual_machine" title="Squawk virtual machine">Squawk</a></li>

<li><a href="Java_Development_Kit" title="Java Development Kit">Java Development Kit</a></li>

<li><a href="OpenJDK" title="OpenJDK">OpenJDK</a></li>

<li><a href="Java_virtual_machine" title="Java virtual machine">Java virtual machine</a></li>

<li><a href="JavaFX" title="JavaFX">JavaFX</a></li>

<li><a href="Maxine_Virtual_Machine" title="Maxine Virtual Machine">Maxine VM</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Platform</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Java_applet" title="Java applet">Applets</a></li>

<li><a href="Jakarta_Servlet" title="Jakarta Servlet">Servlets</a></li>

<li><a href="MIDlet" title="MIDlet">MIDlets</a></li>

<li><a href="Java_Web_Start" title="Java Web Start">Web Start</a> (JNLP)</li>

<li><a href="Java_Platform_Module_System" title="Java Platform Module System">Modules</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Major third-party</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Blackdown_Java" title="Blackdown Java">Blackdown</a></li>

<li><a href="Eclipse_(software)" title="Eclipse (software)">Eclipse</a></li>

<li><a href="GNU_Classpath" title="GNU Classpath">GNU Classpath</a></li>

<li><a href="Apache_Harmony" title="Apache Harmony">Harmony</a></li>

<li><a href="Hibernate_(framework)" title="Hibernate (framework)">Hibernate</a></li>

<li><a href="IcedTea" title="IcedTea">IcedTea</a></li>

<li><a href="Jazelle" title="Jazelle">Jazelle</a></li>

<li><a href="Spring_Framework" title="Spring Framework">Spring</a></li>

<li><a href="Apache_Struts" title="Apache Struts">Struts</a></li>

<li><a href="Oracle_TopLink" title="Oracle TopLink">TopLink</a></li>

<li><a href="WildFly" title="WildFly">WildFly</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">History</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Java_version_history" title="Java version history">Java version history</a></li>

<li><a href="Java_Community_Process" title="Java Community Process">Java Community Process</a></li>

<li><a href="Sun_Microsystems" title="Sun Microsystems">Sun Microsystems</a></li>

<li><a href="Free_Java_implementations" title="Free Java implementations">Free Java implementations</a></li>

<li>Slogan: <a href="Write_once%2C_run_anywhere" title="Write once, run anywhere">Write once, run anywhere</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="List_of_JVM_languages" title="List of JVM languages">JVM languages</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="BeanShell" title="BeanShell">BeanShell</a></li>

<li><a href="Clojure" title="Clojure">Clojure</a></li>

<li><a href="Groovy_(programming_language)" class="mw-redirect" title="Groovy (programming language)">Groovy</a></li>

<li><a href="JRuby" title="JRuby">JRuby</a></li>

<li><a href="Jython" title="Jython">Jython</a></li>

<li><a href="Kotlin_(programming_language)" title="Kotlin (programming language)">Kotlin</a></li>

<li><a href="Processing" title="Processing">Processing</a></li>

<li><a href="Rhino_(JavaScript_engine)" title="Rhino (JavaScript engine)">Rhino</a></li>

<li><a href="Scala_(programming_language)" title="Scala (programming language)">Scala</a></li>

<li><a href="Oxygene_(programming_language)" title="Oxygene (programming language)">Oxygene</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Community</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Conferences</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="JavaOne" title="JavaOne">JavaOne</a></li>

<li><a href="Devoxx" title="Devoxx">Devoxx</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Organizations</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Apache_Software_Foundation" class="mw-redirect" title="Apache Software Foundation">Apache Software Foundation</a></li>

<li><a href="Eclipse_Foundation" title="Eclipse Foundation">Eclipse Foundation</a></li>

<li><a href="Java_Community_Process" title="Java Community Process">Java Community Process</a></li>

<li><a href="Oracle_Corporation" title="Oracle Corporation">Oracle Corporation</a></li>

<li><a href="Sun_Microsystems" title="Sun Microsystems">Sun Microsystems</a>, <a href="Sun_Microsystems_Laboratories" class="mw-redirect" title="Sun Microsystems Laboratories">Sun Microsystems Laboratories</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">People</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="James_Gosling" title="James Gosling">James Gosling</a></li>

<li><a href="Arthur_van_Hoff" title="Arthur van Hoff">Arthur van Hoff</a></li>

<li><a href="Urs_H%C3%B6lzle" title="Urs Hölzle">Urs Hölzle</a></li>

<li><a href="Patrick_Naughton" title="Patrick Naughton">Patrick Naughton</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><td class="navbox-abovebelow" colspan="3"><div> Category • <a href="Portal%3AComputer_programming" title="Portal:Computer programming">Computer programming portal</a></div></td></tr></tbody></table></div></div><div><div class="zim-footer">

This article is issued from <a class="external text" title="Last edited on 2025-04-30" href="https://en.wikipedia.org/wiki/?title=Java_bytecode&oldid=1288099378">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.

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