#22 don't ignore loading exceptions

src/main/java/ninja/javafx/smartcsv/csv/CSVFileReader.java

@@ -29,6 +29,7 @@ package ninja.javafx.smartcsv.csv;
 import ninja.javafx.smartcsv.FileReader;
 import ninja.javafx.smartcsv.fx.table.model.CSVModel;
 import ninja.javafx.smartcsv.fx.table.model.CSVRow;
+import org.supercsv.exception.SuperCsvException;
 import org.supercsv.io.CsvMapReader;
 import org.supercsv.io.ICsvMapReader;
 
@@ -47,10 +48,8 @@ public class CSVFileReader extends CSVConfigurable implements FileReader<CSVMode
     @Override
     public void read(File file) throws IOException {
 
-        ICsvMapReader mapReader = null;
-        try {
-            mapReader = new CsvMapReader(new java.io.FileReader(file.getAbsoluteFile(), Charset.forName(fileEncoding)),
-                    csvPreference);
+        try (ICsvMapReader mapReader = new CsvMapReader(new java.io.FileReader(file.getAbsoluteFile(), Charset.forName(fileEncoding)),
+                csvPreference)) {
             model = new CSVModel();
 
             // the header columns are used as the keys to the Map
@@ -64,11 +63,10 @@ public class CSVFileReader extends CSVConfigurable implements FileReader<CSVMode
                     model.addValue(row, column, customerMap.get(column));
                 }
             }
-
-        } finally {
-            if (mapReader != null) {
-                mapReader.close();
-            }
+        } catch (IOException | SuperCsvException ex) {
+            // TODO perhaps a custom NinjaException that can properly identify and localize the exception message
+            // is this a file not found? is this a corrupt csv? etc
+            throw new IOException("Failed to read " + file + ": " + ex.getMessage(), ex);
         }
     }
 

src/main/java/ninja/javafx/smartcsv/fx/SmartCSVController.java

@@ -52,6 +52,7 @@ import ninja.javafx.smartcsv.fx.table.ValidationCellFactory;
 import ninja.javafx.smartcsv.fx.table.model.CSVModel;
 import ninja.javafx.smartcsv.fx.table.model.CSVRow;
 import ninja.javafx.smartcsv.fx.table.model.CSVValue;
+import ninja.javafx.smartcsv.fx.util.JavaFxUtils;
 import ninja.javafx.smartcsv.fx.util.LoadFileService;
 import ninja.javafx.smartcsv.fx.util.SaveFileService;
 import ninja.javafx.smartcsv.fx.validation.ValidationEditorController;
@@ -85,6 +86,7 @@ import static javafx.scene.layout.AnchorPane.*;
 @Component
 public class SmartCSVController extends FXMLController {
 
+
     ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
     // constants
     ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -595,8 +597,9 @@ public class SmartCSVController extends FXMLController {
         //Show open file dialog
         File file = fileChooser.showOpenDialog(applicationPane.getScene().getWindow());
         if (file != null) {
+            File previousFile = storageFile.getFile();
             storageFile.setFile(file);
-            useLoadFileService(storageFile, t -> resetContent());
+            useLoadFileService(storageFile, t -> resetContent(), () -> storageFile.setFile(previousFile));
         }
     }
 
@@ -625,13 +628,20 @@ public class SmartCSVController extends FXMLController {
         return file;
     }
 
-    private void useLoadFileService(FileStorage fileStorage, EventHandler<WorkerStateEvent> onSucceededHandler) {
+    private void useLoadFileService(FileStorage<?> fileStorage, EventHandler<WorkerStateEvent> onSucceededHandler) {
+        useLoadFileService(fileStorage, onSucceededHandler, () -> {
+            // nothing to rollback
+        });
+    }
+
+    private void useLoadFileService(FileStorage<?> fileStorage, EventHandler<WorkerStateEvent> onSucceededHandler, Runnable rollbackAction) {
         loadFileService.setFileStorage(fileStorage);
         loadFileService.restart();
         loadFileService.setOnSucceeded(onSucceededHandler);
+        loadFileService.setOnFailed(event -> JavaFxUtils.onServiceError(event, "LoadFileService Error", "Failed to load the file.", rollbackAction));
     }
 
-    private void useSaveFileService(FileStorage fileStorage) {
+    private void useSaveFileService(FileStorage<?> fileStorage) {
         saveFileService.setFileStorage(fileStorage);
         saveFileService.restart();
         saveFileService.setOnSucceeded(t -> resetContent());

src/main/java/ninja/javafx/smartcsv/fx/util/JavaFxUtils.java

@@ -0,0 +1,73 @@
+/*
+   The MIT License (MIT)
+   -----------------------------------------------------------------------------
+
+   Copyright (c) 2021 javafx.ninja <info@javafx.ninja>
+
+   Permission is hereby granted, free of charge, to any person obtaining a copy
+   of this software and associated documentation files (the "Software"), to deal
+   in the Software without restriction, including without limitation the rights
+   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+   copies of the Software, and to permit persons to whom the Software is
+   furnished to do so, subject to the following conditions:
+
+   The above copyright notice and this permission notice shall be included in
+   all copies or substantial portions of the Software.
+
+   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+   THE SOFTWARE.
+
+*/
+package ninja.javafx.smartcsv.fx.util;
+
+import javafx.concurrent.Worker;
+import javafx.concurrent.WorkerStateEvent;
+import javafx.scene.control.Alert;
+import ninja.javafx.smartcsv.fx.SmartCSVController;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+/**
+ * This class helps extract useful messages from exceptions
+ * TODO: make I18n maybe?
+ */
+public final class JavaFxUtils {
+
+    private static final Logger logger = LogManager.getLogger(SmartCSVController.class);
+
+    private JavaFxUtils() {
+    }
+
+    public static void onServiceError(WorkerStateEvent event, String windowTitle, String errorHeader) {
+        onServiceError(event, windowTitle, errorHeader, () -> {
+        });
+    }
+
+    public static void onServiceError(WorkerStateEvent event, String windowTitle, String errorHeader, Runnable rollbackAction) {
+        Alert alert = new Alert(Alert.AlertType.ERROR);
+        alert.setTitle(windowTitle);
+        alert.setHeaderText(errorHeader);
+        alert.setContentText(findExceptionMessage(event.getSource()));
+        alert.showAndWait();
+    }
+
+    private static String findExceptionMessage(Worker<?> source) {
+        if (source == null) {
+            return "Cannot identify the source of the event!";
+        } else if (source.getException() == null) {
+            return "The event did not have an exception?";
+        }
+        Throwable exception = source.getException();
+        logger.error("Error in " + source.getClass().getSimpleName(), exception);
+        if (exception.getMessage() == null) {
+            return "Exception of type " + exception.getClass() + " had no message, check the logs.";
+        }
+        return exception.getMessage();
+    }
+
+}

src/main/java/ninja/javafx/smartcsv/fx/util/LoadFileService.java

@@ -34,17 +34,17 @@ import ninja.javafx.smartcsv.files.FileStorage;
  * Service class for async load of a csv file
  */
 @org.springframework.stereotype.Service
-public class LoadFileService extends Service {
+public class LoadFileService extends Service<Void> {
 
-    private FileStorage file;
+    private FileStorage<?> file;
 
-    public void setFileStorage(FileStorage file) {
+    public void setFileStorage(FileStorage<?> file) {
         this.file = file;
     }
 
     @Override
-    protected Task createTask() {
-        return new Task() {
+    protected Task<Void> createTask() {
+        return new Task<>() {
             @Override
             protected Void call() throws Exception {
                 if (file != null) {

src/main/java/ninja/javafx/smartcsv/fx/util/SaveFileService.java

@@ -31,22 +31,22 @@ import javafx.concurrent.Task;
 import ninja.javafx.smartcsv.files.FileStorage;
 
 /**
- * Service class for async load of a csv file
+ * Service class for async save of a csv file
  */
 @org.springframework.stereotype.Service
-public class SaveFileService extends Service {
+public class SaveFileService extends Service<Void> {
 
-    private FileStorage file;
+    private FileStorage<?> file;
 
-    public void setFileStorage(FileStorage value) {
+    public void setFileStorage(FileStorage<?> value) {
         file = value;
     }
 
     @Override
-    protected Task createTask() {
-        return new Task() {
+    protected Task<Void> createTask() {
+        return new Task<>() {
             @Override
-            protected Void call() throws Exception {
+            protected Void call() {
                 try {
                     file.save();
                 } catch (Throwable ex) {