Issue Clearing a JavaFX 8 ComboBox
03 June 2015

Some context: I'v just been bug fixing a JavaFX 8 application. The application has a JavaFX ComboBox that lets a user select a file name from a list. When a selection is made the file is read into a TextBox. This functionality worked fine until a clear button's event was added to the same controller.

@FXML
public void clear(ActionEvent event) {
    [...]
    myCombobox.getSelectionModel().clearSelection();
}

When a JavaFX ComboBox is cleared with .getSelectionModel().clearSelection() the onAction events of the ComboBox is called. This makes it important to null check within the onAction event.

@FXML
public void selected(ActionEvent event) {
    if (myCombobox.getValue() != null) {
        [...]
    }
}

To conclude: If the onAction event of a ComboBox uses the ComboBox's value within the event it pays to null check the ComboBox's value.