How to use the return value of call method of Task class in Javafx

Question

I am using Task class to run background task in javafx application to fetch the data from the database.

public class CustomTask extends Task<ObservableList<ObservableList>> {
    TableView tableview;
    ObservableList<ObservableList> data;

    public CustomTask(TableView tableview) {
        this.tableview = tableview;
    }

    @Override
    protected ObservableList<ObservableList> call() throws Exception {
        DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
        Date date = new Date();
        String SQL = "SELECT * from sell where Date='" + dateFormat.format(date) + "'";
        ResultSet rs = DBConnect.getResultSet(SQL);
        data = DBConnect.generateListDateFromTable(rs, true);

        return data;
    }
}    

How to use the data object.

Answer 1

Example 1 addEventHandler

MyResultObjectType result;
CustomTask task = new CustomTask();
task.addEventHandler(WorkerStateEvent.WORKER_STATE_SUCCEEDED, 
        new EventHandler<WorkerStateEvent>() {
    @Override
    public void handle(WorkerStateEvent t) {
        result = task.getValue();
    }
});

Example 2 setOnSucceeded

MyResultObjectType result;
CustomTask task = new CustomTask();
task.setOnSucceeded(new EventHandler<WorkerStateEvent>() {
    @Override
    public void handle(WorkerStateEvent t) {
        result = task.getValue();
    }
});

Example 3 addListener

task.valueProperty().addListener(new ChangeListener<Task>() {
    @Override
    public void changed(ObservableValue<? extends mytype> obs, 
                        mytype oldValue, mytype newValue) {
        if (newValue != null) {
            System.out.println("Result = " + newValue);
        }
    }
});

Answer 2

Bind to the Task's value property OR provide a task.setOnSucceeded() event handler and call task.getValue() in the provided event handler.