I made a GUI on JavaFX that's for creating timetables. when I open the app I can add plans (Buttons) to day columns (VBox). ofc the changes aren't saved after I close the app: the next time I open it the table is empty. my question is how can I make it save nodes that the user creates so the next time i open the app they're there?
this is the exact part where the nodes get added for what it's worth:
void ask_add_plan(ActionEvent event)
{
Button b = (Button) event.getSource();
VBox v = (VBox) b.getParent();
AnchorPane pop_up = new AnchorPane(); //this pop up is to specify things about the plan
//but i removed unnecessary code for simplicity
VBox pop_up_v = new VBox();
Button add = new Button("Add");
add.setOnAction(e->{
Button plan = new Button(what_to_do.getText());
v.getChildren().add(plan);
container.getChildren().remove(pop_up); //container is the anchor pane everything's in
});
pop_up_v.getChildren().add(add);
pop_up.getChildren().add(pop_up_v);
container.getChildren().add(pop_up); //container is the anchor pane everything's in
}
CodePudding user response:
The JavaFX nodes are just the presentation of your data. They are not meant to be saved. Store the actual data itself in a private field in your class.
- In your Application.stop method, write the data to a file.
- In your Application.start method, read that file and use it to rebuild JavaFX nodes.
private static final Path PLANS_FILE =
Path.of(System.getProperty("user.home"), "plans.txt");
private final List<String> plans = new ArrayList<>();
void ask_add_plan(ActionEvent event) {
// ...
add.setOnAction(e -> {
String planText = what_to_do.getText();
plans.add(planText);
Button plan = new Button(planText);
v.getChildren().add(plan);
container.getChildren().remove(pop_up);
});
}
@Override
public void start(Stage primaryStage)
throws Exception {
// ...
if (Files.exists(PLANS_FILE)) {
plans.addAll(Files.readAllLines(PLANS_FILE));
// Add UI elements for each stored plan.
for (String planText : plans) {
Button planButton = new Button(planText);
v.getChildren().add(planButton);
container.getChildren().remove(pop_up);
}
}
}
@Override
public void stop()
throws IOException {
Files.write(PLANS_FILE, plans);
}
The above is just a simplified example. The file doesn’t have to store just strings.
I get the impression that the data created in the application is more complex than just plan strings. For complex data, XML may be more a suitable file format. Or you can use Java serialization. Or, you can invent your own file format.
You also don’t have to read from and write to a file. You can use a database, if you’re comfortable with database programming. Or you can Preferences (though Preferences are not well suited to storing lists of complex data).
CodePudding user response:
You should use MVP (model-view-presenter) pattern. Saving data in UI layer is not a good practice. Create a model with data and then serialize it.