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A first Example

Canterbury Oberon-2 for JVM can be easily called from a simple command prompt. For example, in order to compile and execute the Slides.java sample on a Windows-95 system, just open a DOS-prompt and enter the following commands (shown here in red color):

C:\COM.webcom.mhc\mhc\obn\samples\slides>java mhc.compiler.obn Slides -m -r
Oberon-2 3.0.1 (c) 1999 Mill Hill & Canterbury Corporation, Ltd.
Unlicenced time-limited evaluation version
Compiling: C:\NEUHOFF\mhc\compiler\runtime\obn\SYSTEM.obn
Importing Java class: java.applet.Applet
Importing Java class: java.lang.Runnable
Importing Java class: java.lang.Thread
Importing Java class: java.awt.Image
Importing Java class: java.awt.Graphics
Importing Java class: java.awt.Event
Importing Java class: java.lang.String
Importing Java class: java.lang.RuntimeException
Compiling: Slides.obn
Compilation done: Slides.obn

C:\COM.webcom.mhc\mhc\obn\samples\slides>appletviewer Slides.html
C:\COM.webcom.mhc\mhc\obn\samples\slides>

As can be seen, the command

java mhc.compiler.obn Slides -m -r

causes the file Slides.obn to be compiled into various *.class files:

Slides.class

Slides_ClickAnimation_init_Frame.class

Slides_ClickAnimation.class 

The -m switch tells the compiler also to recompile other imported Oberon-2 module files if they are updated. This is like a Make-utility for Oberon-2 files integrated into the Oberon-2 compiler.

The -r switch causes the compiler to write the SYSTEM*.class runtime class into the current working directory. This switch should be used when compiling Java applets, otherwise the runtime class will go into the "mhc\compiler\runtime\obn" directory. The latter may be unaccessable from a Web browser environment.

Module Slides.obn has an Oberon-2 class type called ClickAnimation extending the imported class java.applet.Applet. It also declares some type-bound procedures resulting in an override of some inherited methods. In order to run ClickAnimation, an applet-tag has to be declared in an HTML-document. In this case, file Slides.html has an applet-tag (highlighted in green) as follows:

Slides.html
<HTML>
<HEAD>
  <TITLE>A simple click animation applet</TITLE>
</HEAD>
<BODY>
<P>
<APPLET CODE="Slides_ClickAnimation.class"
    CODEBASE=.
    NAME="A simple click animation applet"
    WIDTH="170" HEIGHT="170">
</APPLET>
</BODY>
</HTML>

Calling this file using the JDK appletviewer utility:

appletviewer Slides.html

will launch the Slides_ClickAnimation.class.


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Canterbury Oberon-2 for JVM  (Last documentation update Jun 2, 2000)
Copyright © 1998 Mill Hill & Canterbury Corporation, Ltd. All rights reserved
Please send any comments or corrections to mhc@webcom.com