Groups button and context menu for adding groups

src/main/java/net/sf/jabref/gui/Dialog.java

@@ -0,0 +1,7 @@
+package net.sf.jabref.gui;
+
+import java.util.Optional;
+
+public interface Dialog<R> {
+    Optional<R> showAndWait();
+}

src/main/java/net/sf/jabref/gui/DialogService.java

@@ -88,6 +88,14 @@ Optional<ButtonType> showCustomButtonDialogAndWait(Alert.AlertType type, String
      */
     Optional<ButtonType> showCustomDialogAndWait(String title, DialogPane contentPane, ButtonType... buttonTypes);
 
+    /**
+     * Shows a custom dialog and returns the result.
+     *
+     * @param dialog dialog to show
+     * @param <R>    type of result
+     */
+    <R> Optional<R> showCustomDialogAndWait(Dialog<R> dialog);
+
     /**
      * Notify the user in an non-blocking way (i.e., update status message instead of showing a dialog).
      * @param message the message to show.

src/main/java/net/sf/jabref/gui/FXDialogService.java

@@ -87,6 +87,11 @@ public Optional<ButtonType> showCustomDialogAndWait(String title, DialogPane con
         return alert.showAndWait();
     }
 
+    @Override
+    public <R> Optional<R> showCustomDialogAndWait(Dialog<R> dialog) {
+        return dialog.showAndWait();
+    }
+
     @Override
     public void notify(String message) {
         JabRefGUI.getMainFrame().output(message);

src/main/java/net/sf/jabref/gui/groups/GroupDialog.java

@@ -7,6 +7,7 @@
 import java.awt.Font;
 import java.awt.event.ActionEvent;
 import java.awt.event.ItemListener;
+import java.util.Optional;
 import java.util.regex.Pattern;
 import java.util.regex.PatternSyntaxException;
 
@@ -28,6 +29,8 @@
 import javax.swing.event.CaretListener;
 
 import net.sf.jabref.Globals;
+import net.sf.jabref.JabRefGUI;
+import net.sf.jabref.gui.Dialog;
 import net.sf.jabref.gui.JabRefFrame;
 import net.sf.jabref.gui.fieldeditors.TextField;
 import net.sf.jabref.gui.keyboard.KeyBinding;
@@ -51,7 +54,7 @@
  * Dialog for creating or modifying groups. Operates directly on the Vector
  * containing group information.
  */
-class GroupDialog extends JDialog {
+class GroupDialog extends JDialog implements Dialog<AbstractGroup> {
 
     private static final int INDEX_EXPLICIT_GROUP = 0;
     private static final int INDEX_KEYWORD_GROUP = 1;
@@ -337,6 +340,10 @@ public void actionPerformed(ActionEvent e) {
         }
     }
 
+    public GroupDialog() {
+        this(JabRefGUI.getMainFrame(), null);
+    }
+
     private static String formatRegExException(String regExp, Exception e) {
         String[] sa = e.getMessage().split("\\n");
         StringBuilder sb = new StringBuilder();
@@ -492,4 +499,15 @@ private void setContext(GroupHierarchyType context) {
             independentButton.setSelected(true);
         }
     }
+
+    @Override
+    public Optional<AbstractGroup> showAndWait() {
+        this.setVisible(true);
+        if (this.okPressed()) {
+            AbstractGroup newGroup = getResultingGroup();
+            return Optional.of(newGroup);
+        } else {
+            return Optional.empty();
+        }
+    }
 }

src/main/java/net/sf/jabref/gui/groups/GroupNodeViewModel.java

@@ -1,11 +1,11 @@
 package net.sf.jabref.gui.groups;
 
 import java.util.Objects;
-import java.util.stream.Collectors;
 
 import javafx.application.Platform;
+import javafx.beans.binding.Bindings;
+import javafx.beans.property.SimpleBooleanProperty;
 import javafx.beans.property.SimpleIntegerProperty;
-import javafx.collections.FXCollections;
 import javafx.collections.ObservableList;
 
 import net.sf.jabref.logic.l10n.Localization;
@@ -16,17 +16,18 @@
 import net.sf.jabref.model.groups.GroupTreeNode;
 
 import com.google.common.eventbus.Subscribe;
+import org.fxmisc.easybind.EasyBind;
 
 public class GroupNodeViewModel {
 
     private final String name;
     private final boolean isRoot;
     private final String iconCode;
-    private final boolean isLeaf;
-    private final ObservableList<GroupNodeViewModel> children = FXCollections.observableArrayList();
+    private final ObservableList<GroupNodeViewModel> children;
     private final BibDatabaseContext databaseContext;
     private final GroupTreeNode groupNode;
     private final SimpleIntegerProperty hits;
+    private final SimpleBooleanProperty hasChildren;
 
     public GroupNodeViewModel(BibDatabaseContext databaseContext, GroupTreeNode groupNode) {
         this.databaseContext = Objects.requireNonNull(databaseContext);
@@ -35,15 +36,17 @@ public GroupNodeViewModel(BibDatabaseContext databaseContext, GroupTreeNode grou
         name = groupNode.getName();
         isRoot = groupNode.isRoot();
         iconCode = "";
-        isLeaf = groupNode.isLeaf();
-        children.addAll(groupNode.getChildren().stream().map(child -> new GroupNodeViewModel(databaseContext, child)).collect(Collectors.toList()));
+        children = EasyBind.map(groupNode.getChildren(), child -> new GroupNodeViewModel(databaseContext, child));
+        hasChildren = new SimpleBooleanProperty();
+        hasChildren.bind(Bindings.isNotEmpty(children));
         hits = new SimpleIntegerProperty(0);
         calculateNumberOfMatches();
 
         // Register listener
         databaseContext.getDatabase().registerListener(this);
     }
 
+
     public GroupNodeViewModel(BibDatabaseContext databaseContext, AbstractGroup group) {
         this(databaseContext, new GroupTreeNode(group));
     }
@@ -52,6 +55,10 @@ static GroupNodeViewModel getAllEntriesGroup(BibDatabaseContext newDatabase) {
         return new GroupNodeViewModel(newDatabase, new AllEntriesGroup(Localization.lang("All entries")));
     }
 
+    public SimpleBooleanProperty hasChildrenProperty() {
+        return hasChildren;
+    }
+
     public String getName() {
         return name;
     }
@@ -76,7 +83,6 @@ public boolean equals(Object o) {
         GroupNodeViewModel that = (GroupNodeViewModel) o;
 
         if (isRoot != that.isRoot) return false;
-        if (isLeaf != that.isLeaf) return false;
         if (!name.equals(that.name)) return false;
         if (!iconCode.equals(that.iconCode)) return false;
         if (!children.equals(that.children)) return false;
@@ -91,7 +97,6 @@ public String toString() {
                 "name='" + name + '\'' +
                 ", isRoot=" + isRoot +
                 ", iconCode='" + iconCode + '\'' +
-                ", isLeaf=" + isLeaf +
                 ", children=" + children +
                 ", databaseContext=" + databaseContext +
                 ", groupNode=" + groupNode +
@@ -104,7 +109,6 @@ public int hashCode() {
         int result = name.hashCode();
         result = 31 * result + (isRoot ? 1 : 0);
         result = 31 * result + iconCode.hashCode();
-        result = 31 * result + (isLeaf ? 1 : 0);
         result = 31 * result + children.hashCode();
         result = 31 * result + databaseContext.hashCode();
         result = 31 * result + groupNode.hashCode();
@@ -116,10 +120,6 @@ public String getIconCode() {
         return iconCode;
     }
 
-    public boolean isLeaf() {
-        return isLeaf;
-    }
-
     public ObservableList<GroupNodeViewModel> getChildren() {
         return children;
     }
@@ -145,4 +145,8 @@ private void calculateNumberOfMatches() {
             Platform.runLater(() -> hits.setValue(newHits));
         }).start();
     }
+
+    public GroupTreeNode addSubgroup(AbstractGroup subgroup) {
+        return groupNode.addSubgroup(subgroup);
+    }
 }