Fix nullpointer on import (#5448)

* Enable action "Import into current library" only if an open library exists #5447

* Add CHANGELOG entry #5447

* Fix checkstyle issue

CHANGELOG.md

@@ -39,7 +39,7 @@ We refer to [GitHub issues](https://github.com/JabRef/jabref/issues) by using `#
 - We fixed a problem where the "editor" information has been duplicated during saving a .bib-Database. [#5359](https://github.com/JabRef/jabref/issues/5359)
 - We re-introduced the feature to switch between different preview styles. [#5221](https://github.com/JabRef/jabref/issues/5221)
 - We fixed various issues (including [#5263](https://github.com/JabRef/jabref/issues/5263)) related to copying entries to the clipboard
-
+- We fixed an exception which occurred when trying to import entries without an open library. [#5447](https://github.com/JabRef/jabref/issues/5447) 
 
 
 

src/main/java/org/jabref/gui/JabRefFrame.java

@@ -672,8 +672,8 @@ private MenuBar createMenu() {
 
                 factory.createSubMenu(StandardActions.IMPORT,
                         factory.createMenuItem(StandardActions.MERGE_DATABASE, new OldDatabaseCommandWrapper(Actions.MERGE_DATABASE, this, stateManager)), // TODO: merge with import
-                        factory.createMenuItem(StandardActions.IMPORT_INTO_CURRENT_LIBRARY, new ImportCommand(this, false)),
-                        factory.createMenuItem(StandardActions.IMPORT_INTO_NEW_LIBRARY, new ImportCommand(this, true))),
+                        factory.createMenuItem(StandardActions.IMPORT_INTO_CURRENT_LIBRARY, new ImportCommand(this, false, stateManager)),
+                        factory.createMenuItem(StandardActions.IMPORT_INTO_NEW_LIBRARY, new ImportCommand(this, true, stateManager))),
 
                 factory.createSubMenu(StandardActions.EXPORT,
                         factory.createMenuItem(StandardActions.EXPORT_ALL, new ExportCommand(this, false, Globals.prefs)),

src/main/java/org/jabref/gui/importer/ImportCommand.java

@@ -11,13 +11,16 @@
 import org.jabref.Globals;
 import org.jabref.gui.DialogService;
 import org.jabref.gui.JabRefFrame;
+import org.jabref.gui.StateManager;
 import org.jabref.gui.actions.SimpleCommand;
 import org.jabref.gui.util.FileDialogConfiguration;
 import org.jabref.gui.util.FileFilterConverter;
 import org.jabref.logic.importer.Importer;
 import org.jabref.logic.l10n.Localization;
 import org.jabref.preferences.JabRefPreferences;
 
+import static org.jabref.gui.actions.ActionHelper.needsDatabase;
+
 /**
  * Perform import operation
  */
@@ -30,9 +33,14 @@ public class ImportCommand extends SimpleCommand {
     /**
      * @param openInNew Indicate whether the entries should import into a new database or into the currently open one.
      */
-    public ImportCommand(JabRefFrame frame, boolean openInNew) {
+    public ImportCommand(JabRefFrame frame, boolean openInNew, StateManager stateManager) {
         this.frame = frame;
         this.openInNew = openInNew;
+
+        if (!openInNew) {
+            this.executable.bind(needsDatabase(stateManager));
+        }
+
         this.dialogService = frame.getDialogService();
     }