mmj2 on Java 13?

[Brian Larson]

Running mmj2 on MacOS 10.15.7 with Java 13.0.2, misbehaves and spews error messages like the one below to the console/terminal.

However, on Ubuntu with Java 1.8.0_191, it works swimmingly.

Users experiencing confounding behavior should check what version of Java is installed.

--Brian

java.lang.ClassCastException: class javax.swing.text.AbstractDocument$DefaultDocumentEventUndoableWrapper cannot be cast to class javax.swing.text.AbstractDocument$DefaultDocumentEvent (javax.swing.text.AbstractDocument$DefaultDocumentEventUndoableWrapper and javax.swing.text.AbstractDocument$DefaultDocumentEvent are in module java.desktop of loader 'bootstrap')

at mmj.pa.CompoundUndoManager.undoableEditHappened(CompoundUndoManager.java:110)

at java.desktop/javax.swing.text.AbstractDocument.fireUndoableEditUpdate(AbstractDocument.java:293)

at java.desktop/javax.swing.text.DefaultStyledDocument.setCharacterAttributes(DefaultStyledDocument.java:530)

at mmj.pa.ColorThread.processEvent(ColorThread.java:266)

at mmj.pa.ColorThread.run(ColorThread.java:170)

[Brian Larson]

Java 13 seemed to be the problem.

This tells how to determine what versions you have installed, and how to choose one:

https://stackoverflow.com/questions/21964709/how-to-set-or-change-the-default-java-jdk-version-on-macos

Choosing Java 1.8 made everything better.

--Brian

[Alexander van der Vekens]

Issues with Java versions higher than 8/1.8 were already reported in https://groups.google.com/g/metamath/c/3kN15fc2MdY and https://groups.google.com/g/metamath/c/BzdukfcgZqM/m/pLkfyVqNAwAJ, but I think they were not fixed (in the officially available version). Therefore, mmj2 should be used with Java 1.8 only.