Merge pull request #2393 from neilccbrown/fix-errors-not-shown

Fix errors not being shown in Java editor

bluej/src/main/java/bluej/editor/flow/FlowErrorManager.java

@@ -44,6 +44,7 @@ of the License, or (at your option) any later version.
 import bluej.parser.nodes.*;
 import bluej.parser.nodes.NodeTree.NodeAndPosition;
 import bluej.pkgmgr.target.role.Kind;
+import bluej.utility.BackgroundSupplier;
 import bluej.utility.Debug;
 import bluej.utility.Utility;
 import bluej.utility.javafx.FXPlatformConsumer;
@@ -96,16 +97,10 @@ public void addErrorHighlight(int startPos, int endPos, String message, int iden
 
         EditorFixesManager efm = editor.getEditorFixesManager();
 
-        // prepare for the next compilation (if imports not ready)
-        // or retrieve them (imports are ready)
-        Utility.runBackground(() -> {
-            Stream<AssistContentThreadSafe> imports = efm.getImportSuggestions().values().stream().
-                flatMap(Collection::stream);
-            Platform.runLater(() -> showErrors(editor, sourcePane, startPos, endPos, message, identifier, imports));
-        });
+        showErrors(editor, sourcePane, startPos, endPos, message, identifier, () -> efm.getImportSuggestions().values().stream().flatMap(Collection::stream));
     }
 
-    private void showErrors(FlowEditor editor, FlowEditorPane sourcePane, int startPos, int endPos, String message, int identifier, Stream<AssistContentThreadSafe> imports)
+    private void showErrors(FlowEditor editor, FlowEditorPane sourcePane, int startPos, int endPos, String message, int identifier, BackgroundSupplier<Stream<AssistContentThreadSafe>> imports)
     {
         errorInfos.add(new FlowErrorManager.ErrorDetails(editor, startPos, endPos, message, identifier, imports));
         editor.updateHeaderHasErrors(true);
@@ -207,21 +202,34 @@ public ObservableList<ErrorDetails> getObservableErrorList()
 
     public static class ErrorDetails
     {
+        // Several of these fields can be updated later while suggesting corrections, but all the
+        // access (both read and write) happens on the FX thread:
         public final int startPos;
         public final int endPos;
-        public final String message;
+        public String message;
         private int italicMessageStartIndex;
         private int italicMessageEndIndex;
         public final int identifier;
         public final List<FixSuggestion> corrections = new ArrayList<>();
 
-        private ErrorDetails(FlowEditor editor, int startPos, int endPos, String message, int identifier, Stream<AssistContentThreadSafe> possibleImports)
+        private ErrorDetails(FlowEditor editor, int startPos, int endPos, String message, int identifier, BackgroundSupplier<Stream<AssistContentThreadSafe>> possibleImports)
         {
+            this.message = message;
             this.startPos = startPos;
             this.endPos = endPos;
             this.identifier = identifier;
-            int italicMessageStartIndex = -1, italicMessageEndIndex = -1;
+            this.italicMessageStartIndex = -1;
+            this.italicMessageEndIndex = -1;
+            Utility.runBackground(() -> {
+                Stream<AssistContentThreadSafe> imports = possibleImports.get();
+                Platform.runLater(() -> calculateCorrections(editor, imports));
+            });
+            ;
+        }
 
+        @OnThread(Tag.FXPlatform)
+        private void calculateCorrections(FlowEditor editor, Stream<AssistContentThreadSafe> possibleImports)
+        {
             try
             {
                 int errorLine = editor.getLineColumnFromOffset(startPos).getLine();

bluej/src/main/java/bluej/utility/BackgroundSupplier.java

@@ -0,0 +1,34 @@
+/*
+ This file is part of the BlueJ program.
+ Copyright (C) 2024  Michael Kolling and John Rosenberg
+
+ This program is free software; you can redistribute it and/or
+ modify it under the terms of the GNU General Public License
+ as published by the Free Software Foundation; either version 2
+ of the License, or (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+ This file is subject to the Classpath exception as provided in the
+ LICENSE.txt file that accompanied this code.
+ */
+package bluej.utility;
+
+import threadchecker.OnThread;
+import threadchecker.Tag;
+
+/**
+ * Like supplier but must be run on background thread.
+ */
+@OnThread(Tag.Worker)
+public interface BackgroundSupplier<T>
+{
+    T get();
+}

bluej/src/main/java/bluej/utility/ImportScanner.java

@@ -1,6 +1,6 @@
 /*
  This file is part of the BlueJ program. 
- Copyright (C) 2014,2015,2016,2017,2019,2020,2021  Michael Kolling and John Rosenberg
+ Copyright (C) 2014,2015,2016,2017,2019,2020,2021,2024  Michael Kolling and John Rosenberg
 
  This program is free software; you can redistribute it and/or 
  modify it under the terms of the GNU General Public License 
@@ -136,7 +136,16 @@ private AssistContentThreadSafe getType(String prefix, String name, JavadocResol
                         }
                         else
                         {
-                            f.complete(new AssistContentThreadSafe(new ImportedTypeCompletion(c, javadocResolver)));
+                            AssistContentThreadSafe ac = null;
+                            try
+                            {
+                                ac = new AssistContentThreadSafe(new ImportedTypeCompletion(c, javadocResolver));
+                            }
+                            catch (Throwable t)
+                            {
+                                Debug.reportError(t);
+                            }
+                            f.complete(ac);
                         }
                     });
                     return f.get();