Java classes as executable files

These notes were written by Vuokko-Helena Caseiro.

Introduction

We wish to create an executable file for a given Java application. A Windows user with the Microsoft Virtual Machine (MS VM) installed, should be able to run such an executable file by for example clicking on the file's icon.

To see which version of the MS VM is installed, write "jview" in the dos window or look at the properties of the msjava.dll file in c:\windows\system (exception: under Windows 2000 "jview" doesn't work). The newest version of the MS VM may be found at http://www.microsoft.com/java/ (warning: it seems to be difficult or even impossible to uninstall the MS VM).

The executable file is created by using the jexegen tool from the Microsoft SDK for Java (MS SDK). One then needs to state all the class files to be bundled together. Unfortunately, it is only the old Java 1.1 API that is directly available.

Trying the jexegen tool from the MS SDK

I have tried the jexegen tools under Windows 98 and an older version of the MS VM (namely the 5.00.3167 which is also used by my Internet Explorer 5 to run applets). I installed the MS SDK version 4.0 (this version of the MS SDK doesn't include any MS VM but in other versions an MS VM might be included).

Installation of the MS SDK

1. I downloaded the sdkjava40.exe from http://www.microsoft.com/java/
2. I clicked on the sdkjava40.exe to install. I accepted all suggestions. I ended up having a directory called Microsoft SDK for Java 4.0 inside c:\Programmi (min computer is Italian).
3. I added the following line to the c:\autoexec.bat file:

   set path=%path%;c:\Programmi\"Microsoft SDK for Java 4.0"\bin
   

Information about the installed MS SDK

In the directory Microsoft SDK for Java 4.0/Docs one may read about the product:

• sdkdocs.chm contains much information, including how to create executable files (jegexen), how to compile (jvc), and how to run (jview) (you might want to have a look at the "Tools Reference"). All these three activites take place from the dos window.
• javadocs.chm contains the "Java 1.1 Core API Documentation". "Java 1.1" seems to refer to Sun's enumeration of the versions. Typical Java 2 packages, like e.g. javax.swing, are not included.

Creating an executable file

This is done from the dos window by using the jexegen command. The class files are needed, obtained by compiling for example with Microsoft's jvc or Sun's java.

Example 1

At the beginning of chapter 4 in Java the UML Way by Else Lervik and Vegard B. Havdal there is an example with a class Surface and a class FloorCalculations. By compilation I obtained two class files, Surface.class and FloorCalculations.class (it is not important what compilator is used).

In the dos window I placed myself in the directory where the two class files are located. Then I could create a file FloorCalculations.exe in the following way:

jexegen /v /main:FloorCalculations /out:FloorCalculations.exe Surface.class
FloorCalculations.class

Explanation:

• /v results in better information, in the dos window, about what is going on
• /main: Here the name of the class that contains the main() method is specified.
• /out: Here the name of the resulting executable file is specified.
• Finally the names of the class files to be used, are specified.

Example 2 (incomplete)

Assume that

• The class Test contains the main() method. Test.class is located in c:\myPrograms\testProgram
• Test uses a package myPackage. The package myPackage is in c:\myPackages.

In the dos window I placed myself in c:\. Then I could create a file Test.exe in the following way:

jexegen /v /main:Test /out:Test.exe /base:myPrograms/testProgram Test.class
/base:myPackages myPackage/*.class

Explanation:

• /base: Normally, jexegen assumes that files are in the current directory. By using /base, we change the current directory (relative to the orginal current directory).

Running an executable file

One may open a dos window, place oneself in the directory of the executable file and write the name of the executable file. Or one may click on the icon of the executable file; then a dos window is opened and then closed as soon as the program has been run (this is unfortunate for non-graphical programs that only use the dos window for print-out).

Compilation

This is done from the dos window by using the jvc command. This command is used in the same way as the Sun javac command:

jvc FloorCalculations.java

Running an application

This is done from the dos window by using the jview command. This command is used in the same way as the Sun java command:

jview FloorCalculations

To uninstall the MS SDK

From the control panel.