Macintosh Applet Quirkiness

[CoderMan]

Hi. I have this rather annoying situation in a work project. All my systems are Linux, so naturally I want to compile under Linux using javac. But for some mysterious reason, if I compile under Linux, the resultant Java applet bytecode will not work when viewed in a web browser on a MacOS X system. (While working just fine when viewed on a Windows or Linux system.)

But if I take the same source code, and compile it using javac on a MacOS X system, the resultant Java applet byte code will work fine when viewed in a web browser on any OS.

So, why is it that bytecode must be compiled on a MacOSX system in order to be compatible with an OSX system? Besides not making any sense, it is a real pain because development code and production code have to be built on separate systems.

Many months ago I did some research into this problem, but I wasn't able to find any helpful explanations.

[Fubarable]

I don't do applets nor Mac coding, but I wonder: Do you compile at a compliance level of Java 1.5 or 1.6? I believe that mac supports 1.5 but not 1.6 (anyone -- please correct me if I'm wrong!).

[CoderMan]

I don't do applets nor Mac coding, but I wonder: Do you compile at a compliance level of Java 1.5 or 1.6? I believe that mac supports 1.5 but not 1.6 (anyone -- please correct me if I'm wrong!).

You are correct, Mac systems (at least the ones at my workplace) only support 1.5. Unfortunately, this is not the problem. I did testing again today: the only way I can get the applets to display on a Mac is to compile them on a Mac, using the -source 5 switch. If I compile the same source code on a Linux box, the applet will not show up on the Macs, even with the -source 5 switch.

Unfortunately, the Java console on the Mac systems doesn't provide any information as to why to applet won't display -- all I see is a little red "X" where the applet is supposed to be in the browser. I tested with Firefox and with Safari -- no noticeable difference.

I also noticed during testing that the applet responds less reliable to mouse clicks when displayed on a Mac computer.

[gcalvin]

Do you have an actual JDK installed on your Linux box? Many Linux distributions ship with gcj (Gnu Compiler for Java) as the Java dev and runtime environment. It's not necessarily a problem, but it's worth checking out whether you have a Sun JDK/JRE.

-Gary-

[CoderMan]

Do you have an actual JDK installed on your Linux box? Many Linux distributions ship with gcj (Gnu Compiler for Java) as the Java dev and runtime environment. It's not necessarily a problem, but it's worth checking out whether you have a Sun JDK/JRE.

-Gary-

As far as I can tell, the Sun JDK/JRE are the only ones installed on my system, and I can't locate gcj anywhere on my system.

choward@voltron /rcdp/production/www $ whereis javac
javac: /usr/bin/javac /opt/sun-jdk-1.6.0.20/bin/javac
choward@voltron /rcdp/production/www $ ls -l /usr/bin/javac 
lrwxrwxrwx 1 root root 13 Apr 15 14:03 /usr/bin/javac -> run-java-tool
choward@voltron /rcdp/production/www $ ls -l /usr/bin/run-java-tool 
-rwxr-xr-x 1 root root 1536 Jan 13  2009 /usr/bin/run-java-tool
choward@voltron /rcdp/production/www $ java -version    
java version "1.6.0_20"
Java(TM) SE Runtime Environment (build 1.6.0_20-b02)
Java HotSpot(TM) 64-Bit Server VM (build 16.3-b01, mixed mode)
choward@voltron /rcdp/production/www $ javac -version
javac 1.6.0_20

There doesn't seem to be a more specific javac switch. I am not sure how to find out exactly what "run-java-tool" is calling. Gentoo portage shows the sun Java JDK installed as I intended:

voltron public_html # emerge --search sun-jdk 
Searching...    
[ Results for search key : sun-jdk ]
[ Applications found : 1 ]

*  dev-java/sun-jdk
      Latest version available: 1.6.0.20
      Latest version installed: 1.6.0.20
      Size of files: 165,736 kB
      Homepage:      http://java.sun.com/javase/6/
      Description:   Sun's Java SE Development Kit
      License:       dlj-1.1

[gcalvin]

Yeah, that sure looks like Sun Java. I have had some applet strangeness on my MacBook too, but nothing like complete failure to launch. More like controls that behave strangely.

-Gary-