I have problem when trying to close current scene and open up another scene when menuItem is selected. My main stage is coded as below:
public void start(Stage primaryStage) throws Exception {
    primaryStage.setTitle("Shop Management");
    FXMLLoader myLoader = new FXMLLoader(getClass().getResource("cartHomePage.fxml"));
    Pane myPane = (Pane) myLoader.load();
    CartHomePageUI controller = (CartHomePageUI) myLoader.getController();
    controller.setPrevStage(primaryStage);
    Scene myScene = new Scene(myPane);
    primaryStage.setScene(myScene);
    primaryStage.show();
}
When the program is executed, it will go to the cartHomePage.fxml. From there, I can select to go to create product or create category when the menu item is selected. Here is my action event:
Stage prevStage;
public void setPrevStage(Stage stage){
     this.prevStage = stage;
}
 public void gotoCreateCategory(ActionEvent event) throws IOException {
  Stage stage = new Stage();
    stage.setTitle("Shop Management");
    FXMLLoader myLoader = new FXMLLoader(getClass().getResource("createCategory.fxml"));
    Pane myPane = (Pane) myLoader.load();            
    Scene scene = new Scene(myPane);
    stage.setScene(scene);
    prevStage.close();
    setPrevStage(stage);
    stage.show();       
}
//Method to change scene when menu item create product is on click
@FXML
public void gotoCreateProduct(ActionEvent event) throws IOException {
   Stage stage = new Stage();
    stage.setTitle("Shop Management");
    FXMLLoader myLoader = new FXMLLoader(getClass().getResource("creatProduct.fxml"));
    Pane myPane = (Pane) myLoader.load();            
    Scene scene = new Scene(myPane);
    stage.setScene(scene);
    prevStage.close();
    setPrevStage(stage);
    stage.show();      
}
However, I can only switch the stage once. For example, my default page is cartHomePage.fxml. When I run the program, first I go to create product stage. After that, I cannot go to anywhere any more. The error message is:
java.lang.IllegalStateException: Location is not set.
and Null Pointer Exception
I did set the stage after I close it and pass it around. I wonder which part went wrong.
Thanks in advance.
 
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
    