Java Glossary : JDK

Last updated 2004-06-28 by Roedy Green ©1996-2004 Canadian Mind Products

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JDK

Sun's Java Development Kit. Officially now foppishly called the SDK Software Development Kit. Further, to confuse everyone, Sun's marketing people refer to all Java versions 1.2+ as Java 2. It consists of a compiler written itself in Java, and a run time interpreter for your particular platform. You compose programs using a traditional text editor. The term JDK also refers generally to the set of Sun-supplied classes including the AWT. Apple calls the JDK the MRJ. You cannot distribute the JDK with your program. You must distribute the stripped down JRE instead.

Version	Executables	Documentation	What's New
Java 1.5.0 beta 2  SDK/JDK	download look in the SDK column under J2SE. You probably don't want this beta (preliminary) version.	download 35 MB in zipped HTML format. The link is way at the bottom of the page after the JDK executable downloads. I suggest you mark the docs directory as compressed to save space after you download and unzip it. Online docs.	release notes. To use any of the new new enum or generics features you must compile with javac -source 1.5 MyProg.java You might consider renaming src.zip to src.jar so that your IDE can see the source files for cross referencing. This release includes major changes to the Java language such as boxing/unboxing (automatic int <-> Integer conversion), generic (Collections know what sort of objects are in them), enhanced for loops for iterating over Collections, and typesafe enumerations, and variable numbers of argument to a method.
Java 1.4.2_04  SDK/JDK	download look in the SDK column under J2SE.This is most likely the version you want. The Windows Installation version is 88 MB and contains NetBeans. If you don't want NetBeans, look lower on the page under 32-bit/64-bit for Windows/Linux/Solaris SPARC 32-bit for Solaris x86 where you can get the vanilla 49 MB JDK. You then get a choice of online or offline install. Offline is preferable since it lets you reinstall later even if you have no Internet access or if Sun stops making it available. Online uses less disk space since it downloads as needed during the install. You can also put the offline version on CD for backup or to pass on to others. The JDK includes source in src.zip and class files in jre\lib\rt.jar. Includes the JRE and Java Web Start runtime jawaws.exe. Does not include JavaMail or JAF.	download 49 MB in zipped HTML format. The link is way at the bottom of the page after the JDK executable downloads. I suggest you mark the docs directory as compressed to save space after you download and unzip it. Online docs. 1.4.2_04 is mainly bug fixes.	release notes. You might consider renaming src.zip to src.jar so that your IDE can see the source files for cross referencing. It will install two copies of the JRE, a private one in J:\j2sdk1.4.2_04\jre for the sdk tools, and a public one in C:\Program Files\Java\j2re1.4.2_04 for all apps to use. Surely the tools should be modified to use the public one and drop the private copy.
Java 1.4.1_03  SDK/JDK (old)	download look in the SDK column, 38 MB (including source in src.zip and class files in jre\lib\rt.jar). Includes JRE. Includes Java Web Start 1.2 runtime jawaws.exe.	download 33 MB in zipped HTML format. The link is way at the bottom of the page after the JDK executable downloads. I suggest you mark the docs directory as compressed to save space after you download and unzip it. Online docs.	release notes. You might consider renaming src.zip to src.jar so that your IDE can see the source files for cross referencing.
Java 1.3.1 JDK (old)	download 30 MB (including source in src.jar and class files in rt.jar) Mac requires OSX plus Java 1.3 upgrade.	download 23 MB in HTML format download in WinHelp Format.	release notes. Java Naming and Directory InterfaceTM (JNDI), Strings longer than 64K can now be serialized., Drag and Drop enhancements, Java Sound AIFF, AU, wav, MIDI Type 0, MIDI Type 1, and Rich Music Format (RMF), HTTP 1.1 client-side support, Math vs StrictMath class allows faster operations at the expense of 100% reproducibility on different machines, HotSpot dynamic optimiser. This download installs both the JDK and the JRE. It installs the JRE twice, once in the JDK directory you specify and once in C:\Program Files\Java\j2re1.4.2_04 .
Java 1.2.1 Enterprise Edition J2EE	download 11 MB	download 7.5 MB	Requires Java SDK 1.3. Handles Enterprise JavaBeans, JavaServer Pages, and Servlets.
Java 1.2.2 JDK (old)	download 20 MB (including source in src.jar) download Linux download Plug-in download HTML Converter	download 16 MB in HTML format download in WinHelp Format.	release notes. The new features mainly revolve around Swing, the platform independent set of pluggable look and feel components, JDBC 2.0, Collections and weak references. Browsers will not run JDK 1.2 Applets unless you install the plug-in into your browser and convert your HTML with the HTML converter.
Mac OS X JDK 1.4.1	executables	documentation	Java for Mac OS X.
Mac OS JDK 1.1.8 MRJ 2.2.5	executables	documentation	Java for the classic Mac OS.
Everything on CD	sign up: to have a free CD of the latest Java software mailed to you on CD.	This provides a convenient disk to copy to give to others without high speed internet. It provides backup for you, especially of old versions Sun may stop posting. A new CD will arrive every quarter.

Polishing The Install

• Set your JAVA_HOME environment variable to the JRE directory e.g. J:\j2sdk1.4.2_04. Some software such as Caucho Resin finds Java using this variable rather than poking around in the registry.
• If you use Jikes, set up your JIKESPATH environment variable to include the JRE's rt.jar with .;C:\;C:\Program Files\Java\j2re1.4.2_04\lib\rt.jar
• Set up your J: drive to point to the drive where you installed the JDK. For detailed instructions see J: drive.

Contents

Once you have the JDK installed what do you get?

• In the J:\j2sdk1.4.2_04 directory you will find src.zip/ src.jar which contains the source to the Java core libraries.
• In the J:\j2sdk1.4.2_04\bin directory you will find javac.exe, java.exe, javaw.exe and javadoc.exe.
• In the J:\j2sdk1.4.2_04\lib directory you will find the jar files, especially dt.jar/ rt.jar/ classes.zip which contains most of the Java core library class files. Sun likes to rename this file frequently.
• In the J:\j2sdk1.4.2_04\JRE directory is a duplicate of the crucial J:\j2sdk1.4.2_04\bin files that are also distributed separately bundled in the JRE, including Java Web Start. In jre\lib\ext you can put jars you want automatically included on the path.
• In C:\Program Files\Java\j2re1.4.2_04\ is yet a third copy of the crucial files, a duplicate of the JRE. Why three copies? "If we told you, we would have to shoot you."

Caveats

Sun downloads often fail because they give them the non-standard MIME type of magnus-internal/cgi. Set your browser to treat this MIME type just like application/octet-stream to simply download the files.

Note, Sun's install instructions for the older releases may tell you to hit download software. There is no such button. Hit continue instead. The JDK package optionally upgrades your Winsock. Undo with C:\WINDOWS\WS2BACKUP\WS2BACKUP.BAT or remove/reinstall Win95 dialup networking. The new socket software did not work for me and for a few other people I talked to. Plan your recovery before you install. Without a working Winsock you won't be able to ask for help or go searching the net for a solution.

The JDK does not include the javax packages (except for Swing). You must download those separately.

Failed Installs

If a JDK (or JRE) fails to behave normally, try this:

1. Uninstall all Java JDKs and JREs with Start | Settings control panel | add/remove programs.
2. Go into the registry and delete all reference to Java i.e. HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft.
3. Delete all the files in C:\Documents and Settings\Administrator\Application Data\Sun\Java or your equivalent.
4. Reinstall. If you are feeling lucky, you can try skipping steps 2 and 3.
5. Sometimes uninstall, install to a different directory, uninstall, install to the original directory will clear it.
6. If Java runs standalone, but does not work in your browser, test your JRE browser hooks by running Wassup. It should tell you that your browser is using the JVM version you just installed. Look for the line marked java.version. If Wassup does not run, or you have the wrong version, go into Start | Settings Control Panel | Java Plug-In | Browser and turn off each browser, then click apply, then turn them on again, then hit apply again. Then retest with Wassup.
7. Have a look at the hidden Java Web Start control file C:\Documents and Settings\ Administrator\Application Data\Java\Deployment\deployment.properties. Don't edit it. If you see something wonky (e.g. references to an uninstalled JVM), go into the control panel | Java control panel and turn things off and on again and hit apply to refresh the file. If that does not work, make a backup and try deleting the deployment.properties file, then try going into the Java control panel and clicking reset. The set everything up from scratch. If that does not work try editing a copy of the original deployment.properties file, sorting the entries first to make it clearer what they do, and installing it back as the official deployment.properties.

Retrofitting

You can download some of the JDK 1.2 features and retrofit them into JDK 1.1. These include:

1. Swing
2. IBM's JDK 1.2 security classes.
3. Collection classes (except the natural order stuff).
4. Help engine.

Why would you do such a goofy thing rather than just upgrading? Microsoft's IE 5 is stuck at Java 1.1.5. Either you must upgrade your customers to IE 6 and Java 1.4, or somehow make all your code work at the 1.1.5 level.

flipping between different JVMs ¤ IDE ¤ J2EE ¤ JRE ¤ JRockIt ¤ more friendly uninstaller ¤ MRJ ¤ SDK ¤ Testing Your JRE

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