Using Jikes and the Microsoft VM

As all of you know, installing and configuring the Java Development Kit is difficult and time consuming, whether you use the Sun, IBM, or even the Microsoft version. Wouldn't it be nice if there was a way to download a "JDK lite", that was smaller and easier to install? Well, how would you like a complete JDK that consists of three files, weighing less than 800K? Impossible, you say? Well, if you're running Windows and MS Internet Explorer, maybe not.

In the past week, I've been trying this technique out, and it seems to work. The only requirements are that you have a recent MS Java Virtual Machine, like the one you get with Internet Explorer 4 and up.

Here are the three easy steps to follow to see if it will work for you:

Check and configure your Microsoft Virtual Machine.
Download and place the the three files jikes.exe, Sc1.exe, and SciTEGlobal.properties in your Windows directory.
Test your application.

Step 1: Check the MSJVM

The Microsoft Java Virtual Machine [MSJVM] is usually installed when you install Microsoft Internet Explorer. The first step in this process is to make sure you have the MSJVM installed. Once that's finished, you must tell Windows to create the classes.zip file you'll need to use the jikes compiler.

Here are the necessary incantations:

A. Is MSJVM Installed?

Start an "MS-DOS Prompt". In Windows 95/98/NT, you can do that from the Start button as shown here. In Windows ME and Windows 2000 they renamed the MS DOS Prompt the "Command Window", and moved it to the Accessories menu.

Launching the MS-DOS Prompt from the Start Button.

At the command prompt type jview, and press the Enter key.

Running the jview program from the MS-DOS prompt.

If you see the message "Bad command or filename" then you don't have the MS VM installed, and you can't go any further. Click here to download the current MSVM from Microsoft. If you see a list of jview options, as shown here,

A listing of jview options shown at the MS-DOS prompt.

then you are ready for the next step--creating the classes.zip file required by your Java compiler.

B. Creating the Classes

To do this, type clspack -auto at the command prompt and press the Enter key.

The clspack program will build a copy of classes.zip and place it in your C:\Windows\java\classes directory. [On Windows NT and 2K, it will be placed in the C:\WINNT\System32\java\classes directory instead.] While clspack is creating the file it will display a progress dialog that looks like this:

Building classes.zip with clspack -auto.

Step 2: Install the Compiler and Editor

If all has gone well, then copy the three files jikes.exe [520K], Sc1.exe [158K], and SciTEGlobal.properties [3K] into your C:\Windows directory. [With Windows NT and Windows 2000, you should copy the files to the C:\WINNT\System32 directory instead.]

A. Drag the Shortcut

Once the files are safely downloaded, use Windows Explorer to drag Sc1.exe to the desktop. This creates a shortcut as shown here:

B. Change the Name

When the shortcut appears on the desktop, you probably want to change its name.

C. Working Directory

Once that's done, right-click the icon, and choose Properties from the menu.

Opening the Jikes Properties dialog with the context menu.

When the Jikes Properties dialog appears, change the "Start In" directory to the directory where you keep your Java source code. In the illustration, I've change it from C:\Windows to C:\MyFiles. [You must make sure that the directory exists, though!]

Step 3: Try It Out

It's always a good idea to spend a few minutes testing your installation. Let's go through each part step by step.

A. The Working Directory

Double-click your new desktop icon, and let's make sure the working directory is set correctly. Choose Open from the File menu. You should be shown a list of files in your working directory, (the directory where you keep your source code files), as shown here:

If, instead of your working directory, you see the Windows directory, go back to Step 2C and make sure the Jikes Properties Start In field is correctly filled out. If you enter the name of a non-existent directory, for instance, your entry will be ignored.

B. Creating a Java Application

Create a new Java application using the text shown here. Save your file as FirstApp.java. [Click here to download FirstApp.java.] You use the New, Open, and Save toolbar icons just like you would with any Windows editor, or you can use the menu instead.

C. Compiling

Once you've entered and saved FirstApp.java, choose Compile from the Tools menu, or press Ctrl+F7, and the editor will launch the jikes compiler.

At the bottom of the editor window you'll see the command-line that is passed to jikes. This command-line is designed to work with Windows 95/98. You'll have to change it to work with Windows NT or Windows 2000. If you are using one of those operating systems, skip ahead to Section H. Properties, and make the necessary changes.

If all went well, you'll see an exit code of 0 printed. That means your code had no syntax errors.

D. Running

You can run Java applications from within the editor by choosing Go from the Tools menu, or by pressing F5. The editor is set to run console mode applications that produce output. If you want to launch GUI applications [not applets], then make changes to the editor's properties file as detailed in Section H.

The output will appear in the same window used by your compiler messages. The blue output is produced by the editor, and the black output is produced by your program.

A word of warning, however. You cannot run console-mode programs that expect input from the keyboard in this way. The program will appear to hang, but you won't be given an input window where you can supply the necessary information. When this occurs, you can select Stop Executing from the Tools menu or press Ctrl+Break.

If you want to run console-mode applications that take input from the keyboard, you'll need to start them from the command-line as detailed in Section G.

E. Syntax Errors

Syntax errors are inevitable. The jikes compiler will give you fairly good error messages, and the Sc1 editor will help you out by showing you where your errors occur. Let's see how that works by changing the public in FirstApp.java to Public, as shown below.

When you compile your code, Sc1 will display the error message from jikes in the compile window at the bottom of the screen. When you double-click one of the error messages, Sc1 will place your cursor on the offending line, as you can see.

F. Applets

You can write and compile applets as well as applications using the Sc1 editor. You can also automatically launch the appletviewer to display your applet as well. Start by entering the code for FirstApplet.java as shown here. [Click here if you want to download FirstApplet.java instead.]

Next, create a separate HTML file to display the applet. A minimal HTML file, like that shown here should suffice.

<applet code=FirstApplet.class width=200 height=100>
</applet>

Once you've saved your file, while FirstApplet.html is still selected, open the Tools menu. You should see the Appletviewer appear on the menu as shown here.

Selecting Appletviewer from the Tools menu, or pressing Ctrl+0 [Control + zero], will launch Microsoft's version of the appletviewer program. It also launches Jview in a separate command-window to start up the appletviewer as well.

G. The Command Line

Sometimes, you might want to run a command-line program that requires input from the keyboard, or you might want to run an application or applet without starting up the Sc1 editor. To do this, open any MS-DOS Prompt and use Microsoft's jview command.

Here's an example that runs the FirstApp application from the command-line:

C:\MyFiles> jview FirstApp

Here's an example that runs the FirstApplet applet from the command-line:

C:\MyFiles> jview /a FirstApplet.html

Here's a picture of both application and applet running together.

Compiling your programs from the command-line is a little more difficult, however. You will need to set the CLASSPATH environmental variable or use the same incantation used by the Sc1 editor to compile your code. [Of course, you can always put that incantation in a batch file, and then use the batch file to compile your code.]

H. Changing Properties

The Sc1 editor uses the file SciTEGlobal.properties which you placed in your C:\Windows directory to control many of its operations. You can open the file by selection Open Global Options File from the Options menu.

I've placed various notes at the beginning of the initializtion file showing the different things you might want to change. The Sc1 editor is extremely configurable, however. If you want a more complete listing of your available options, you can click here to read the Sc1 docs online.

Let Me Know

I have a limited number of systems to test this information on. If you've tried this on different versions of Windows [NT, ME, 2000], let me know about your experiences. If you had to make changes, send me a screenshot of what you needed to do. [To make screenshots, just press Alt+PrintScreen and then paste the resulting image into a WordPad document.]

For those of you who are interested

Sc1.exe is version 1.35 downloaded directly from www.scintilla.org.
The jikes compiler is the MingW32 version 1.1.2, which I've compressed with upx version 1.06. You can get jikes [including the sources] from http://oss.software.ibm.com/developerworks/opensource/jikes/
You can get upx from http://wildsau.idv.uni-linz.ac.at/mfx/upx.html

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