Select multiple dates with DatePicker

Question

I am trying to create a DatePicker that selects multiple dates. I am able to select multiple dates but I would like to keep the DatePicker open while I select them. Proble

Answer 1

If you check DatePickerContent class, you can find that each time a new DateCell is created, an EventHandler of type MOUSE_CLICKED is added to it. This handler will call selectDayCell(DateCell) when the user clicks on a cell. selectDayCell(DateCell) sets the new date value and hides the DatePicker:

protected void createDayCells() {
    final EventHandler dayCellActionHandler = ev -> {
        if (ev.getButton() != MouseButton.PRIMARY) {
            return;
        }
        DateCell dayCell = (DateCell)ev.getSource();
        selectDayCell(dayCell);
        lastFocusedDayCell = dayCell;
    };
    for (int row = 0; row < 6; row++) {
        for (int col = 0; col < daysPerWeek; col++) {
            DateCell dayCell = createDayCell();
            dayCell.addEventHandler(MouseEvent.MOUSE_CLICKED, dayCellActionHandler);
            dayCells.add(dayCell);
        }
    }
    dayCellDates = new LocalDate[6 * daysPerWeek];
}

public void selectDayCell(DateCell dateCell) {
    datePicker.setValue(dayCellDate(dateCell));
    datePicker.hide();
}

If you're using Java 9 or newer, you can extend DatePickerContent class and override the selectDayCell(DateCell) method to not hide the DatePicker after a cell is selected:

public void selectDayCell(DateCell dateCell) {
    datePicker.setValue(dayCellDate(dateCell));
}

Unfortunately, in Java 8, DatePickerContent has a package-private constructor so you can't extend from it. As a workaround, you can add another EventHandler on mouse click that will show the DatePicker again after a cell is clicked:

EventHandler mouseClickedEventHandler = clickEvent -> {
    if (clickEvent.getButton() == MouseButton.PRIMARY) {
        datePicker.show();
    }
    clickEvent.consume();
};

In your cell factory:

@Override
public void updateItem(LocalDate item, boolean empty) {
    super.updateItem(item, empty);
    //...
    if (item != null && !empty) {
        //...
        addEventHandler(MouseEvent.MOUSE_CLICKED, mouseClickedEventHandler);
    } else {
        //...
        removeEventHandler(MouseEvent.MOUSE_CLICKED, mouseClickedEventHandler);
    }
}