The Java Development Kit (JDK) is an implementation of either one of the Java Platform, Standard Edition; Java Platform, Enterprise Edition or Java Platform, Micro Edition platforms released by Oracle Corporation in the form of a binary product aimed at Java developers on Solaris, Linux, Mac OS X or Windows. The JDK includes a private JVM and a few other resources to finish the development of a Java Application. Since the introduction of the Java platform, it has been by far the most widely used Software Development Kit (SDK). On 17 November 2006, Sun announced that they would release it under the GNU General Public License (GPL), thus making it free software. This happened in large part on 8 May 2007, when Sun contributed the source code to the OpenJDK.
The JDK has as its primary components a collection of programming tools, including:
appletviewer – this tool can be used to run and debug Java applets without a web browser
apt – the annotation-processing tool
extcheck – a utility that detects JAR file conflicts
idlj – the IDL-to-Java compiler. This utility generates Java bindings from a given Java IDL file.
jabswitch – the Java Access Bridge. Exposes assistive technologies on Microsoft Windows systems.
java – the loader for Java applications. This tool is an interpreter and can interpret the class files generated by the javac compiler. Now a single launcher is used for both development and deployment. The old deployment launcher, jre, no longer comes with Sun JDK, and instead it has been replaced by this new java loader.
javac – the Java compiler, which converts source code into Java bytecode
javadoc – the documentation generator, which automatically generates documentation from source code comments
jar – the archiver, which packages related class libraries into a single JAR file. This tool also helps manage JAR files.
javafxpackager – tool to package and sign JavaFX applications
jarsigner – the jar signing and verification tool
javah – the C header and stub generator, used to write native methods
javap – the class file disassembler
javaws – the Java Web Start launcher for JNLP applications
JConsole – Java Monitoring and Management Console
jdb – the debugger
jhat – Java Heap Analysis Tool (experimental)
jinfo – This utility gets configuration information from a running Java process or crash dump. (experimental)
jmap Oracle jmap - Memory Map– This utility outputs the memory map for Java and can print shared object memory maps or heap memory details of a given process or core dump. (experimental)
jmc – Java Mission Control
jps – Java Virtual Machine Process Status Tool lists the instrumented HotSpot Java Virtual Machines (JVMs) on the target system. (experimental)
jrunscript – Java command-line script shell.
jstack – utility that prints Java stack traces of Java threads (experimental)
jstat – Java Virtual Machine statistics monitoring tool (experimental)
jstatd – jstat daemon (experimental)
keytool – tool for manipulating the keystore
pack200 – JAR compression tool
policytool – the policy creation and management tool, which can determine policy for a Java runtime, specifying which permissions are available for code from various sources.
VisualVM – visual tool integrating several command-line JDK tools and lightweight performance and memory profiling capabilities
wsimport – generates portable JAX-WS artifacts for invoking a web service.
xjc – Part of the Java API for XML Binding (JAXB) API. It accepts an XML schema and generates Java classes.
Experimental tools may not be available in future versions of the JDK.
The JDK also comes with a complete Java Runtime Environment, usually called a private runtime, due to the fact that it is separated from the "regular" JRE and has extra contents. It consists of a Java Virtual Machine and all of the class libraries present in the production environment, as well as additional libraries only useful to developers, such as the internationalization libraries and the IDL libraries.
Copies of the JDK also include a wide selection of example programs demonstrating the use of almost all portions of the Java API.
Ambiguity between a JDK and an SDK
The JDK forms an extended subset of a software development kit (SDK). It includes "tools for developing, debugging, and monitoring Java applications". Oracle strongly suggests to now use the term JDK to refer to the Java SE Development Kit. The Java EE SDK is available with or without the JDK, by which they specifically mean the Java SE 7 JDK.
In addition to the most widely used JDK discussed in this article, there are other JDKs commonly available for a variety of platforms, some of which started from the Sun JDK source and some that did not. All adhere to the basic Java specifications, but often differ in explicitly unspecified areas, such as garbage collection, compilation strategies, and optimization techniques. They include:
In development or in maintenance mode:
Azul Systems Zing, low latency JDK for Linux;
Azul Systems / OpenJDK-based Zulu for Linux, Windows, Mac OS X, embedded and the cloud;
OpenJDK / IcedTea;
GNU's Classpath and GCJ (The GNU Compiler for Java);
Aicas JamaicaVM;
IBM J9 JDK, for AIX, Linux, Windows, MVS, OS/400, Pocket PC, z/OS;
Not being maintained or discontinued:
Apache Harmony
Apple's Mac OS Runtime for Java JVM/JDK for Classic Mac OS
Blackdown Java – Port of Sun's JDK for Linux
Oracle Corporation's JRockit JDK, for Windows, Linux, and Solaris;
