I just installed JDK 1.4.1 on a machine running Mac OS 10.2.8. This must be manually downloaded from apple.com. There is a version for 10.2.x, separate from the version for 10.3.

With that done, I was still getting an error message from the JEdit MacOS plugin: "MAC OS Plug-in requires a later version of java (MRJ 99)". I looked into the source code. It requires 1.4.1, minimum. Further, it is comparing a property from the JRE to a value defined in a file called MacOS.props, in the MacOS.jar file in the JEdit install directories. If the JRE value is less than the value in the props file, it gives the error and exits.

Running java -version in the terminal now gives me this:

java version "1.4.1_01"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1_01-69.1)
Java HotSpot(TM) Client VM (build 1.4.1_01-24, mixed mode)

The value in question is "69.1", which is displayed above, and is the value returned from calling System.getProperty("mrj.version") in a Java program. This is being compared with the value set by this line in MacOS.props:

MacOSPlugin.depend.mrj.version=99

The logic says, at least in my case, that 69.1 is less than 99, so display the error and bail out.

Why this logic is present, I don't know. However, I eliminated the error by these steps:

1. Extract MacOS.props from the MacOS.jar file.
2. Make this change: "MacOSPlugin.depend.mrj.version=0"
3. Put the changed MacOS.props file back into MacOS.jar.

On restarting JEdit, obvious success is indicated by the menu bar being displayed at the top of the screen instead of inside the JEdit window. Hoorah.

i read, that the mrj is for mac os 10.3. is it impossible to install it on 10.2??