JDK stands for Java Development Kit. This is a free Java application development kit. It includes the Java compiler (javac), standard Java class libraries, examples, documentation, various utilities, and the Java executable system (JRE). The kit is distributed by Oracle Corporation (formerly Sun Microsystems). The JDK does not include a Java IDE, so a JDK-only developer must use an external text editor and compile their programs using command-line utilities.
Download JDK from official site: http://www.oracle.com/technetwork/articles/javase/index-jsp-138363.html
The JDK set of programs and classes contains:
- compiler from source to javac bytecodes;
- a java interpreter containing the JVM implementation;
- lightweight jre interpreter (not available in recent versions);
- the appletviewer applet viewer, which replaces the browser;
- jdb debugger;
- javap disassembler;
- jar archiving and compression program;
- a program for collecting and generating javadoc documentation;
- a program for generating C header files for creating “native” javah methods;keytool generation program;
- the native2ascii program that converts binary files to text;
- rmic and rmiregistry programs for working with remote objects;
- the serialver program, which determines the version number of the class;
- libraries and header files of “native” methods;
- Java API (Application Programming Interface) class library.
Sun Microsystems has been actively developing and updating the JDK, with new versions released almost every year.
In 1996, the first version was released – JDK 1.0, which was modified to version 1.0.2. In this version, the Java API class library contained 8 packages.
The entire JDK 1.0.2 was packaged in a single file about 5 MB in size, and after unpacking it occupied about 8 MB on disk.
JDK 1.1 was released in 1997, and its last modification, 1.1.8, was released in 1998. This version had 23 class packages and was 8.5 MB packed and about 30 MB unpacked.
In the first versions of the JDK, all Java API library packages were packed into a single classes.zip archive file and called directly from this archive, it did not need to be unpacked.
Since then, the JDK has been heavily redesigned.
JDK 1.2 was released in December 1998 and already contained 57 class packages. In archive form, this is a file of almost 20 MB in size and another separate file of more than 17 MB in size with packed documentation. The full version is located on 130 MB of disk space, of which about 80 MB is occupied by documentation.
Starting with this release, Sun’s proprietary Java technology products were referred to as Java 2 Platform, Standard Edition, or J2SE for short, and the name Java 2 became established in the literature. 2 JDK 1.2 includes additional class packages called the Standard Extension API.
In the J2SE JDK 1.5.0, released at the end of 2004, there were already under a hundred packages that made up the Core API (Application Programming Interface). When packaged, this is a file of about 46 MB and an optional packaged documentation file of the same size. At the same time, another renaming of technology took place.
The first digit was removed from the version and they began to write Java 2 Platform, Standard Edition 5.0, abbreviated as J2SE 5.0 and JDK 5.0, although the name JDK 1.5.0 is retained in the in-house documentation.
The latest J2SE 5.0 update, JDK 1.5.0_22, was released on November 3, 2009.
In the sixth version, released in early 2007, the number 2 was removed from the name of the technology and they began to write Java Platform, Standard Edition 6, abbreviated as Java SE 6 and JDK 6. However, the former designation remains in the internal documentation, for example, the last one at the time of writing The book update is denoted by JDK 1.6.0_26.
In the summer of 2011, the seventh version of Java SE 7 appeared and is being distributed by JDK 1.7.0, which is the subject of this book.
Java SE JDK is created for each platform: MS Windows, Solaris, Linux, separately, and the documentation is written in HTML and is the same on all platforms. Therefore, it is recorded in a separate file. For example, for MS Windows, the Java SE JDK 1.7.0 file is called jdk-7-windows-i586.exe with an update number added, and the documentation file is called jdk-7-fcs-bin-b147-apidocs-27_jun_2011.zip.
The archive can be copied from the same site. The Java EE SDK is an add-on to Java SE and is therefore installed after the Java SE JDK. However, on the same site there is a full version of the archive, which contains both the Java EE SDK and the Java SE JDK.
Java EE is included with application servers, so if you installed JBoss, GlassFish, or another application server, you already have a set of Java EE classes.
In addition to the JDK, Oracle also separately distributes the JRE (Java Runtime Environment) set.