Fix group hit counter when adding entries

CHANGELOG.md

@@ -61,6 +61,7 @@ We refer to [GitHub issues](https://github.com/JabRef/jabref/issues) by using `#
 - We fixed an issue where the order of fields in customized entry types was not saved correctly. [#4033](http://github.com/JabRef/jabref/issues/4033)
 - We fixed an issue where the groups tree of the last database was still shown even after the database was already closed.
 - We fixed an issue where the "Open file dialog" may disappear behind other windows. https://github.com/JabRef/jabref/issues/3410
+- We fixed an issue where the number of entries matched was not updated correctly upon adding or removing an entry. [#3537](https://github.com/JabRef/jabref/issues/3537)
 - We fixed an issue where the default icon of a group was not colored correctly.
 - We fixed an issue where the first field in entry editor was not focused when adding a new entry. [#4024](https://github.com/JabRef/jabref/issues/4024)
 - We reworked the "Edit file" dialog to make it resizeable and improved the workflow for adding and editing files https://github.com/JabRef/jabref/issues/2970

src/main/java/org/jabref/gui/groups/GroupNodeViewModel.java

@@ -11,6 +11,7 @@
 import javafx.beans.property.SimpleBooleanProperty;
 import javafx.beans.property.SimpleIntegerProperty;
 import javafx.collections.FXCollections;
+import javafx.collections.ListChangeListener;
 import javafx.collections.ObservableList;
 import javafx.scene.input.Dragboard;
 import javafx.scene.paint.Color;
@@ -29,15 +30,13 @@
 import org.jabref.model.FieldChange;
 import org.jabref.model.database.BibDatabaseContext;
 import org.jabref.model.entry.BibEntry;
-import org.jabref.model.entry.event.EntryEvent;
 import org.jabref.model.groups.AbstractGroup;
 import org.jabref.model.groups.AutomaticGroup;
 import org.jabref.model.groups.GroupEntryChanger;
 import org.jabref.model.groups.GroupTreeNode;
 import org.jabref.model.strings.StringUtil;
 
 import com.google.common.base.Enums;
-import com.google.common.eventbus.Subscribe;
 import de.jensd.fx.glyphs.materialdesignicons.MaterialDesignIcon;
 import org.fxmisc.easybind.EasyBind;
 
@@ -85,7 +84,7 @@ public GroupNodeViewModel(BibDatabaseContext databaseContext, StateManager state
         expandedProperty.addListener((observable, oldValue, newValue) -> groupNode.getGroup().setExpanded(newValue));
 
         // Register listener
-        databaseContext.getDatabase().registerListener(this);
+        databaseContext.getDatabase().getEntries().addListener(this::onDatabaseChanged);
 
         ObservableList<Boolean> selectedEntriesMatchStatus = EasyBind.map(stateManager.getSelectedEntries(), groupNode::matches);
         anySelectedEntriesMatched = BindingsHelper.any(selectedEntriesMatchStatus, matched -> matched);
@@ -212,10 +211,9 @@ public GroupTreeNode getGroupNode() {
     }
 
     /**
-    * Gets invoked if an entry in the current database changes.
-    */
-    @Subscribe
-    public void listen(@SuppressWarnings("unused") EntryEvent entryEvent) {
+     * Gets invoked if an entry in the current database changes.
+     */
+    private void onDatabaseChanged(ListChangeListener.Change<? extends BibEntry> change) {
         calculateNumberOfMatches();
     }