External changes are not reported due to JavaFX threading issue

[tobiasdiez]

Modify the bib file externally and get the following error:

java.util.concurrent.ExecutionException: java.lang.IllegalStateException: Not on FX application thread; currentThread = JabRef LowPriorityCachedThreadPool
  at java.util.concurrent.FutureTask.report(FutureTask.java:122) ~[?:1.8.0_181]
  at java.util.concurrent.FutureTask.get(FutureTask.java:192) ~[?:1.8.0_181]
  at org.jabref.JabRefExecutorService.executeInterruptableTaskAndWait(JabRefExecutorService.java:108) ~[classes/:?]
  at org.jabref.gui.collab.DatabaseChangeMonitor.fileUpdated(DatabaseChangeMonitor.java:80) ~[classes/:?]
  at java.lang.Iterable.forEach(Iterable.java:75) [?:1.8.0_181]
  at org.jabref.gui.util.DefaultFileUpdateMonitor.notifyAboutChange(DefaultFileUpdateMonitor.java:67) [classes/:?]
  at org.jabref.gui.util.DefaultFileUpdateMonitor.run(DefaultFileUpdateMonitor.java:55) [classes/:?]
  at org.jabref.JabRefExecutorService$NamedRunnable.run(JabRefExecutorService.java:162) [classes/:?]
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_181]
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_181]
  at java.lang.Thread.run(Thread.java:748) [?:1.8.0_181]
Caused by: java.lang.IllegalStateException: Not on FX application thread; currentThread = JabRef LowPriorityCachedThreadPool
  at com.sun.javafx.tk.Toolkit.checkFxUserThread(Toolkit.java:279) ~[jfxrt.jar:?]
  at com.sun.javafx.tk.quantum.QuantumToolkit.checkFxUserThread(QuantumToolkit.java:423) ~[jfxrt.jar:?]
  at javafx.scene.web.WebEngine.checkThread(WebEngine.java:1243) ~[jfxrt.jar:?]
  at javafx.scene.web.WebEngine.<init>(WebEngine.java:879) ~[jfxrt.jar:?]
  at javafx.scene.web.WebEngine.<init>(WebEngine.java:868) ~[jfxrt.jar:?]
  at javafx.scene.web.WebView.<init>(WebView.java:273) ~[jfxrt.jar:?]
  at org.jabref.gui.PreviewPanel.<init>(PreviewPanel.java:83) ~[classes/:?]
  at org.jabref.gui.collab.EntryDeleteChangeViewModel.<init>(EntryDeleteChangeViewModel.java:47) ~[classes/:?]
  at org.jabref.gui.collab.ChangeScanner.createBibEntryDiff(ChangeScanner.java:171) ~[classes/:?]
  at org.jabref.gui.collab.ChangeScanner.lambda$run$7(ChangeScanner.java:140) ~[classes/:?]
  at java.util.ArrayList.forEach(ArrayList.java:1257) ~[?:1.8.0_181]
  at org.jabref.gui.collab.ChangeScanner.run(ChangeScanner.java:140) ~[classes/:?]
  at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) ~[?:1.8.0_181]
  at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[?:1.8.0_181]
  ... 3 more

While the symptoms might be easy to fix, a bit more work should be invested to make EntryDeleteChangeViewModel free of JavaFX controls...

[Siedlerchr]

Well, in fact it's related to the conversion of the ChangeScanner to javafx.

The thing is that these ChangeViewModels operate on a Swing TreeNode (DefaultMutuableTreeNode) as logic. First thing would be to extract logic and display of messages and the rendered preview panel.

[Siedlerchr]

Fixed by #4693