I have the following implementation of the call method of the class SaveData that extends the Task class in JavaFX:

@Override
    protected Void call() {
        try {
            SheetWriter publicationWriter = new SheetWriter(destinationPath);
            publicationWriter.write(publicationHeaders);
            if (savingOption.equals("excel")) {
                for (JSONArray jsonArray : searchResult) {
                    for (int i = 0; i < jsonArray.length(); i++) {
                        Publication currentPublication = new Publication(jsonArray.getJSONObject(i));
                        publicationWriter.write(currentPublication.getSCVData());
                    }
                }
            }
            publicationWriter.close();
        } catch (IOException e) {
            System.out.println(e.getMessage());
            throw new RuntimeException("Exception occurred");
        }
        return null;
    }

The idea is to loop through a list of JSONArrays where each contains JSONObjects, and save them into a CSV file using CSVWriter of openCSV.

This is SheetWriter class:

public class SheetWriter {
    FileWriter fileWriter;
    CSVWriter csvWriter;

    public SheetWriter(String fileName) throws IOException {
        fileWriter = new FileWriter(fileName);
        csvWriter = new CSVWriter(fileWriter);
    }

    public void write(String[] inputArray) {
        csvWriter.writeNext(inputArray);
    }

    public void close() throws IOException {
        // fileWriter.close();
        csvWriter.close();
    }
}

The action is triggered when the user clicks the save button. This is the code that handles the action when triggered:

 saveButton.setOnAction(event -> new Thread(() -> {
            Platform.runLater(() -> saveButton.setDisable(true));
            SaveData saveDataTask = new SaveData("C:\Users\PC\IdeaProjects\NewsPaperScrapper\src\result\data.csv", result);

            if (currentOption.equals("excel"))
                saveDataTask.setSavingOption("excel");
            else
                saveDataTask.setSavingOption("json");

            saveDataTask.setOnSucceeded(e -> {
                System.out.println("Saved!!");
                Platform.runLater(() -> saveButton.setDisable(false));
            });

            new Thread(saveDataTask).start();
        }).start());

The issue is that setOnSucceeded is invoked immediately and does not wait for the task to complete and save the CSV file.

I would like to know what is causing the issue. knowing that I have tried changing the return type of the task to boolean, and also running the task on the same thread using the run method