Fix NPE cases in FileDialog Configuration

CHANGELOG.md

@@ -35,7 +35,8 @@ We refer to [GitHub issues](https://github.com/JabRef/jabref/issues) by using `#
 - We fixed a bug that did not allow the correct re-export of the MS-Office XML field `msbib-accessed` with a different date format [#2859](https://github.com/JabRef/jabref/issues/2859).
 - We fixed some bugs that prevented the display of FileAnnotations that were created using the Foxit Reader. [#2839, comment](https://github.com/JabRef/jabref/issues/2839#issuecomment-302058227).
 - We fixed an error that prevented the FileAnnotation tab to load when the entry had no bibtexkey [#2903](https://github.com/JabRef/jabref/issues/2903).
-- We fixed a bug that recursive RegExpBased search found a file in a subdirectory multiple times and non-recursive RegExpBased search erroneously found files in subdirectories.
+- We fixed a bug which which could result in an exception when opening/saving files from/to a nonexistent directory [#2917](https://github.com/JabRef/jabref/issues/2917).
+- We fixed a bug where recursive RegExpBased search found a file in a subdirectory multiple times and non-recursive RegExpBased search erroneously found files in subdirectories.
 ### Removed
 
 

src/main/java/org/jabref/gui/util/FileDialogConfiguration.java

@@ -47,7 +47,7 @@ public List<FileChooser.ExtensionFilter> getExtensionFilters() {
 
     public static class Builder {
 
-        List<FileChooser.ExtensionFilter> extensionFilter = new ArrayList<>();
+        private final List<FileChooser.ExtensionFilter> extensionFilter = new ArrayList<>();
         private Path initialDirectory;
         private FileChooser.ExtensionFilter defaultExtension;
         private String initialFileName;
@@ -72,22 +72,28 @@ public FileDialogConfiguration build() {
         }
 
         public Builder withInitialDirectory(Path directory) {
-
-            //Dir must be a folder, not a file
-            if (!Files.isDirectory(directory)) {
-                directory = directory.getParent();
-            }
-            //The lines above work also if the dir does not exist at all!
-            //NULL is accepted by the filechooser as no inital path
-            if (!Files.exists(directory)) {
-                directory = null;
+            if (directory == null) { //It could be that somehow the path is null, for example if it got deleted in the meantime
+                initialDirectory = null;
+            } else { //Dir must be a folder, not a file
+                if (!Files.isDirectory(directory)) {
+                    directory = directory.getParent();
+                }
+                //The lines above work also if the dir does not exist at all!
+                //NULL is accepted by the filechooser as no inital path
+                if (!Files.exists(directory)) {
+                    directory = null;
+                }
+                initialDirectory = directory;
             }
-            initialDirectory = directory;
             return this;
         }
 
         public Builder withInitialDirectory(String directory) {
-            withInitialDirectory(Paths.get(directory));
+            if (directory != null) {
+                withInitialDirectory(Paths.get(directory));
+            } else {
+                initialDirectory = null;
+            }
             return this;
         }
 

src/test/java/org/jabref/gui/util/FileDialogConfigurationTest.java

@@ -0,0 +1,93 @@
+package org.jabref.gui.util;
+
+import java.io.IOException;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.EnumSet;
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
+
+import javafx.stage.FileChooser;
+
+import org.jabref.logic.util.FileExtensions;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import static org.junit.Assert.assertEquals;
+
+public class FileDialogConfigurationTest {
+
+    @Rule public TemporaryFolder folder = new TemporaryFolder();
+
+    @Test
+    public void testWithValidDirectoryString() throws IOException {
+        String tempFolder = folder.newFolder().toString();
+
+        FileDialogConfiguration fileDialogConfiguration = new FileDialogConfiguration.Builder()
+                .withInitialDirectory(tempFolder).build();
+
+        assertEquals(Optional.of(Paths.get(tempFolder)), fileDialogConfiguration.getInitialDirectory());
+    }
+
+    @Test
+    public void testWithValidDirectoryPath() throws IOException {
+        Path tempFolder = folder.newFolder().toPath();
+
+        FileDialogConfiguration fileDialogConfiguration = new FileDialogConfiguration.Builder()
+                .withInitialDirectory(tempFolder).build();
+
+        assertEquals(Optional.of(tempFolder), fileDialogConfiguration.getInitialDirectory());
+    }
+
+    @Test
+    public void testWithNullStringDirectory() {
+        String tempFolder = null;
+        FileDialogConfiguration fileDialogConfiguration = new FileDialogConfiguration.Builder()
+                .withInitialDirectory(tempFolder).build();
+
+        assertEquals(Optional.ofNullable(tempFolder), fileDialogConfiguration.getInitialDirectory());
+    }
+
+    @Test
+    public void testWithNullPathDirectory() {
+        Path tempFolder = null;
+        FileDialogConfiguration fileDialogConfiguration = new FileDialogConfiguration.Builder()
+                .withInitialDirectory(tempFolder).build();
+
+        assertEquals(Optional.ofNullable(tempFolder), fileDialogConfiguration.getInitialDirectory());
+    }
+
+    @Test
+    public void testSingleExtension() {
+        FileDialogConfiguration fileDialogConfiguration = new FileDialogConfiguration.Builder()
+                .withDefaultExtension(FileExtensions.BIBTEX_DB).build();
+
+        FileChooser.ExtensionFilter filter = toFilter(FileExtensions.BIBTEX_DB);
+
+        assertEquals(filter.getExtensions(), fileDialogConfiguration.getDefaultExtension().getExtensions());
+    }
+
+    @Test
+    public void testMultipleExtension() {
+        EnumSet<FileExtensions> extensions = EnumSet.allOf(FileExtensions.class);
+
+        FileDialogConfiguration fileDialogConfiguration = new FileDialogConfiguration.Builder()
+                .addExtensionFilters(extensions).build();
+
+        List<FileChooser.ExtensionFilter> extensionFilters = extensions.stream().map(this::toFilter)
+                .collect(Collectors.toList());
+
+        //We use size here as we otherwise would compare object references, as extension filters does not override equals
+        assertEquals(extensionFilters.size(), fileDialogConfiguration.getExtensionFilters().size());
+
+    }
+
+    private FileChooser.ExtensionFilter toFilter(FileExtensions extension) {
+        return new FileChooser.ExtensionFilter(extension.getDescription(),
+                extension.getExtensionsAsList().stream().map(ending -> "*." + ending).collect(Collectors.toList()));
+    }
+
+}