Simple example of a calendar display. Supports some basic CSS styling and direct localization (in practice you would almost never need localization, just use the default locale; but it was fun to play with). Includes a simple example.

calendar.css

.calendar-grid {
	-fx-hgap: 4 ;
	-fx-vgap: 4 ;
	-fx-padding: 4 ;
}

.calendar-header {
	-fx-alignment: center ;
	-fx-font-size: 18pt ;
	-fx-font-weight: bold ;
}

.calendar-cell {
	-fx-padding: 4 ;
	-fx-alignment: center ;
}

.calendar-cell:before-display-month, .calendar-cell:after-display-month {
	-fx-opacity: 0.4 ;
}

.calendar-header-cell {
	-fx-padding: 4 ;
	-fx-alignment: center ;
	-fx-font-weight: bold ;
}

CalendarView.java

import java.time.DayOfWeek;
import java.time.LocalDate;
import java.time.YearMonth;
import java.time.format.DateTimeFormatter;
import java.time.format.TextStyle;
import java.time.temporal.ChronoUnit;
import java.time.temporal.WeekFields;
import java.util.Locale;

import javafx.beans.binding.Bindings;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.css.PseudoClass;
import javafx.geometry.HPos;
import javafx.scene.Node;
import javafx.scene.control.Label;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.GridPane;

public class CalendarView {
    private final ObjectProperty<YearMonth> month = new SimpleObjectProperty<>();
    
    private final ObjectProperty<Locale> locale = new SimpleObjectProperty<>(Locale.getDefault());
    
    private final BorderPane view ;
    private final GridPane calendar ;
    
    public CalendarView(YearMonth month) {
        view = new BorderPane();
        view.getStyleClass().add("calendar");
        calendar = new GridPane();
        calendar.getStyleClass().add("calendar-grid");

        Label header = new Label();
        header.setMaxWidth(Double.MAX_VALUE);
        header.getStyleClass().add("calendar-header");
        
        this.month.addListener((obs, oldMonth, newMonth) -> 
            rebuildCalendar());
        
        this.locale.addListener((obs, oldLocale, newLocale) -> 
            rebuildCalendar());
        
        view.setTop(header);
        view.setCenter(calendar);
        
        view.getStylesheets().add(getClass().getResource("calendar.css").toExternalForm());
        
        setMonth(month);
        
        header.textProperty().bind(Bindings.createStringBinding(() -> 
            this.month.get().format(DateTimeFormatter.ofPattern("MMMM yyyy", locale.get())), 
            this.month, this.locale));
    }
    
    public CalendarView() {
        this(YearMonth.now()) ;
    }
    
    public void nextMonth() {
        month.set(month.get().plusMonths(1));
    }
    
    public void previousMonth() {
        month.set(month.get().minusMonths(1));
    }
    
    private void rebuildCalendar() {
        
        calendar.getChildren().clear();
        
        WeekFields weekFields = WeekFields.of(locale.get());
        
        LocalDate first = month.get().atDay(1);
        
        int dayOfWeekOfFirst = first.get(weekFields.dayOfWeek()) ;
        
        // column headers:
        for (int dayOfWeek = 1 ; dayOfWeek <= 7 ; dayOfWeek++) {
            LocalDate date = first.minusDays(dayOfWeekOfFirst - dayOfWeek);
            DayOfWeek day = date.getDayOfWeek() ;
            Label label = new Label(day.getDisplayName(TextStyle.SHORT_STANDALONE, locale.get()));
            label.getStyleClass().add("calendar-day-header");
            GridPane.setHalignment(label, HPos.CENTER);
            calendar.add(label, dayOfWeek - 1, 0);
        }
        
        LocalDate firstDisplayedDate = first.minusDays(dayOfWeekOfFirst - 1);
        LocalDate last = month.get().atEndOfMonth() ;
        int dayOfWeekOfLast = last.get(weekFields.dayOfWeek());
        LocalDate lastDisplayedDate = last.plusDays(7 - dayOfWeekOfLast);
        
        PseudoClass beforeMonth = PseudoClass.getPseudoClass("before-display-month");
        PseudoClass afterMonth = PseudoClass.getPseudoClass("after-display-month");
                
        for (LocalDate date = firstDisplayedDate ; ! date.isAfter(lastDisplayedDate) ; date = date.plusDays(1)) {
            Label label = new Label(String.valueOf(date.getDayOfMonth()));
            label.getStyleClass().add("calendar-cell");
            label.pseudoClassStateChanged(beforeMonth, date.isBefore(first));
            label.pseudoClassStateChanged(afterMonth, date.isAfter(last));

            GridPane.setHalignment(label, HPos.CENTER);
            
            int dayOfWeek = date.get(weekFields.dayOfWeek()) ;
            int daysSinceFirstDisplayed = (int) firstDisplayedDate.until(date, ChronoUnit.DAYS);
            int weeksSinceFirstDisplayed = daysSinceFirstDisplayed / 7 ;
            
            calendar.add(label, dayOfWeek - 1, weeksSinceFirstDisplayed + 1);
        }
    }
    
    public Node getView() {
        return view ;
    }

    public final ObjectProperty<YearMonth> monthProperty() {
        return this.month;
    }
    

    public final YearMonth getMonth() {
        return this.monthProperty().get();
    }
    

    public final void setMonth(final YearMonth month) {
        this.monthProperty().set(month);
    }

    public final ObjectProperty<Locale> localeProperty() {
        return this.locale;
    }
    

    public final java.util.Locale getLocale() {
        return this.localeProperty().get();
    }
    

    public final void setLocale(final java.util.Locale locale) {
        this.localeProperty().set(locale);
    }

}

CalendarViewTest.java

import java.util.Locale;

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ComboBox;
import javafx.scene.control.ListCell;
import javafx.scene.layout.BorderPane;
import javafx.stage.Stage;

public class CalendarViewTest extends Application {

	@Override
	public void start(Stage primaryStage) {
		CalendarView calendarView = new CalendarView() ;
		
		Button next = new Button(">");
		next.setOnAction(e -> calendarView.nextMonth());
		
		Button previous = new Button("<");
		previous.setOnAction(e -> calendarView.previousMonth());
		
		ComboBox<Locale> localeCombo = new ComboBox<>();
		localeCombo.getItems().addAll(Locale.getAvailableLocales());
		localeCombo.setValue(Locale.getDefault());
		
		localeCombo.setCellFactory(lv -> new LocaleCell());
		localeCombo.setButtonCell(new LocaleCell());
		
		calendarView.localeProperty().bind(localeCombo.valueProperty());
		
		BorderPane.setAlignment(localeCombo, Pos.CENTER);
		BorderPane.setMargin(localeCombo, new Insets(10));
		
		BorderPane root = new BorderPane(calendarView.getView(), localeCombo, next, null, previous);
		Scene scene = new Scene(root);
		primaryStage.setScene(scene);
		primaryStage.show();
	}
	
	public static class LocaleCell extends ListCell<Locale> {
	    @Override
	    public void updateItem(Locale locale, boolean empty) {
	        super.updateItem(locale, empty);
	        setText(locale == null ? null : locale.getDisplayName(locale));
	    }
	}

	public static void main(String[] args) {
		launch(args);
	}
}

Hi James,

Am hoping to try out your Java Calendar. There are 4 errors in Eclipse Markers as Java Problems.

Please communicate back.

Thank you.

Jon

works fine @ dataSQL