JavaFX - creating custom dialogs using fxml - javafx

Question

I'm new in javafx and I was trying to create custom dialogs/alerts. The thing is that I'm using Scene Builder to design the GUI, and I want to modify the dialog each time I load the fxml file (i.e change the title, label text, etc.), so I wanted to know if there's a way to send parameters and modify the stage/scene, or any other way I can achieve this.
To be more specific, let's say there's an error I want to handle anywhere in my program, so I load a new fxml file that represents the error dialog I created, and I modify the components inside it, depending on the type of error I need to handle, similar to, for example, JOptionPane.showMessageDialog(...) in swing.

Answer 1

For the use case you describe, you can just use the Dialog API, or the specialized Alert class that is part of that.
For the more general question you ask:
I wanted to know if there's a way to send parameters and change the stage/scene
the way to do this is to use the custom component mechanism described in the documentation.
In short, make a subclass of the UI type you need that loads the FXML file, and defines the properties you need, e.g.
public class ExceptionPane extends BorderPane {
private final ObjectProperty<Exception> exception ;
public ObjectProperty<Exception> exceptionProperty() {
return exception ;
}
public final Exception getException() {
return exceptionProperty().get();
}
public final void setException(Exception exception) {
exceptionProperty().set(exception);
}
#FXML
private final TextArea stackTrace ;
#FXML
private final Label message ;
public ExceptionPane() throws Exception {
FXMLLoader loader = new FXMLLoader(getClass().getResource("path/to/fxml"));
loader.setRoot(this);
loader.setController(this);
loader.load();
exception.addListener((obs, oldException, newException) -> {
if (newException == null) {
message.setText(null);
stackTrace.setText(null);
} else {
message.setText(newException.getMessage());
StringWriter sw = new StringWriter();
newException.printStackTrace(new PrintWriter(sw));
stackTrace.setText(sw.toString());
}
});
}
}
Then define the FXML using a "dynamic root":
<!-- imports etc -->
<fx:root type="BorderPane" ...>
<center>
<TextArea fx:id="stackTrace" editable="false" wrapText="false" />
</center>
<top>
<Label fx:id="message" />
</top>
</fx:root>
Now you can use this directly in either Java or in FXML:
try {
// some code...
} catch (Exception exc) {
ExceptionPane excPane = new ExceptionPane();
excPane.setException(exc);
Stage stage = new Stage();
stage.setScene(new Scene(excPane));
stage.show();
}
or
<fx:define fx:id="exc"><!-- define exception somehow --></fx:define>
<ExceptionPane exception="${exc}" />