Refine main directory not found error message

CHANGELOG.md

@@ -18,7 +18,7 @@ Note that this project **does not** adhere to [Semantic Versioning](http://semve
 
 ### Changed
 
-
+- We refined the 'main directory not found' error message. [#9625](https://github.com/JabRef/jabref/pull/9625)
 
 
 

src/main/java/org/jabref/gui/preferences/linkedfiles/LinkedFilesTabViewModel.java

@@ -53,21 +53,28 @@ public LinkedFilesTabViewModel(DialogService dialogService, PreferencesService p
 
         mainFileDirValidator = new FunctionBasedValidator<>(
                 mainFileDirectoryProperty,
-                input -> {
+                mainDirectoryPath -> {
+                    ValidationMessage error = ValidationMessage.error(String.format(
+                            "%s%n%s%n%n%s%n%n%s > %s > %s",
+                            Localization.lang("Main directory not found"),
+                            mainDirectoryPath,
+                            Localization.lang("Please select a valid main directory under"),
+                            Localization.lang("Linked files"),
+                            Localization.lang("File directory"),
+                            Localization.lang("Main file directory")
+                    ));
+
                     try {
-                        Path path = Path.of(mainFileDirectoryProperty.getValue());
-                        return (Files.exists(path) && Files.isDirectory(path));
+                        Path path = Path.of(mainDirectoryPath);
+                        if (!(Files.exists(path) && Files.isDirectory(path))) {
+                            return error;
+                        }
                     } catch (InvalidPathException ex) {
-                        return false;
+                        return error;
                     }
-                },
-                ValidationMessage.error(String.format("%s > %s > %s %n %n %s",
-                        Localization.lang("File"),
-                        Localization.lang("External file links"),
-                        Localization.lang("Main file directory"),
-                        Localization.lang("Directory not found")
-                        )
-                )
+                    // main directory is valid
+                    return null;
+                }
         );
     }
 
@@ -120,7 +127,7 @@ ValidationStatus mainFileDirValidationStatus() {
     @Override
     public boolean validateSettings() {
         ValidationStatus validationStatus = mainFileDirValidationStatus();
-        if (!validationStatus.isValid()) {
+        if (!validationStatus.isValid() && useMainFileDirectoryProperty().get()) {
             validationStatus.getHighestMessage().ifPresent(message ->
                     dialogService.showErrorDialogAndWait(message.getMessage()));
             return false;

src/main/resources/l10n/JabRef_en.properties

@@ -337,8 +337,6 @@ Extension=Extension
 
 External\ Changes\ Resolver=External Changes Resolver
 
-External\ file\ links=External file links
-
 External\ programs=External programs
 
 Failed\ to\ import\ by\ ID=Failed to import by ID
@@ -2529,3 +2527,6 @@ Use\ the\ field\ FJournal\ to\ store\ the\ full\ journal\ name\ for\ (un)abbrevi
 Library\ to\ import\ into=Library to import into
 
 Multiline=Multiline
+
+Main\ directory\ not\ found=Main directory not found
+Please\ select\ a\ valid\ main\ directory\ under=Please select a valid main directory under