#22 don't ignore loading exceptions

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();
+    }
+
+}