Allow user to only select Mondays in DatePicker - javafx

Question

I am working on a javafx project and I have included a DatePicker. I want to make the user only be able to select Mondays
DatePicker startDate = new DatePicker();
Any Ideas if it's possible?

Answer 1

There are two things you need to do:
Veto the change if the user changes the date in the text field to a date that is not a Monday. You can do this with the converter property of the DatePicker.
Disable all the cells in the popup that are not Mondays. You can do this with the dayCellFactory.
Simple example:
import java.time.DayOfWeek;
import java.time.LocalDate;
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.DateCell;
import javafx.scene.control.DatePicker;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
import javafx.util.Callback;
import javafx.util.StringConverter;
public class DatePickerMondaysOnly extends Application {
#Override
public void start(Stage primaryStage) {
DatePicker datePicker = new DatePicker();
StringConverter<LocalDate> defaultConverter = datePicker.getConverter();
datePicker.setConverter(new StringConverter<LocalDate>() {
#Override
public String toString(LocalDate object) {
return defaultConverter.toString(object);
}
#Override
public LocalDate fromString(String string) {
LocalDate date = defaultConverter.fromString(string);
if (date.getDayOfWeek() == DayOfWeek.MONDAY) {
return date ;
} else {
// not a Monday. Revert to previous value.
// You could also, e.g., return the closest Monday here.
return datePicker.getValue();
}
}
});
datePicker.setDayCellFactory(dp -> new DateCell() {
#Override
public void updateItem(LocalDate item, boolean empty) {
super.updateItem(item, empty);
setDisable(empty || item.getDayOfWeek() != DayOfWeek.MONDAY);
}
});
// Just for debugging: make sure we only see Mondays:
datePicker.valueProperty().addListener((obs, oldDate, newDate) -> {
if (newDate.getDayOfWeek() != DayOfWeek.MONDAY) {
System.out.println("WARNING: date chosen was not a Monday");
}
System.out.println(newDate + " (" + newDate.getDayOfWeek()+")");
});
StackPane root = new StackPane(datePicker);
root.setPadding(new Insets(20));
primaryStage.setScene(new Scene(root));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}