Chapter 16 Exercise 29, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

16.29 (Display a calendar)
Write a program that displays the calendar for the current month.
You can use the Prior and Next buttons to show the calendar of
the previous or next month. Display the dates in the current
month in black and display the dates in the previous month and
next month in gray, as shown in Figure 16.48.

import java.util.GregorianCalendar;
public class MyCalendar extends GregorianCalendar {

    public MyCalendar(int year, int month, int dayOfMonth) {
        super(year, month, dayOfMonth);

    }

    /**return month name in English*/
    public String getMonthName() {
        return getMonthName(get(MONTH));
    }

    public static String getMonthName(int month) {
        String monthName = null;

        switch (month) {
            case 0: monthName = "January"; break;
            case 1: monthName = "February"; break;
            case 2: monthName = "March"; break;
            case 3: monthName = "April"; break;
            case 4: monthName = "May"; break;
            case 5: monthName = "June"; break;
            case 6: monthName = "July"; break;
            case 7: monthName = "August"; break;
            case 8: monthName = "September"; break;
            case 9: monthName = "October"; break;
            case 10: monthName = "November"; break;
            case 11: monthName = "December"; break;
            default:
        }

        return monthName;
    }

    public static String getDayOfWeekName(int day) {
        String dayOfWeekName = null;

        day = day % 7;

        switch (day) {
            case 0: dayOfWeekName = "Sunday"; break;
            case 1: dayOfWeekName = "Monday"; break;
            case 2: dayOfWeekName = "Tuesday"; break;
            case 3: dayOfWeekName = "Wednesday"; break;
            case 4: dayOfWeekName = "Thursday"; break;
            case 5: dayOfWeekName = "Friday"; break;
            case 6: dayOfWeekName = "Saturday"; break;
            default:
        }

        return dayOfWeekName;
    }

    /**Find the number of days in a month*/
    public int daysInMonth() {
        switch (get(MONTH)) {
            case 0:
            case 2:
            case 4:
            case 6:
            case 7:
            case 9:
            case 11:
                return 31;
            case 1:
                if (isLeapYear(get(YEAR))) return 29;
                else return 28;
            case 3:
            case 5:
            case 8:
            case 10:
                return 30;
            default: return 0;
        }
    }

    /**Find the number of days in a month*/
    public static int daysInMonth(int month, int year) {
        return new MyCalendar(year, month, 1).daysInMonth();
    }

    /** Get the start day of month/1/year */
    public int getStartDay() {

        int month = get(MONTH) + 1;
        int day = 1;
        int year = get(YEAR);

        if (month == 1) {
            month = 13;
            year--;
        } else if (month == 2) {
            month = 14;
            year--;
        }

        int k = year % 100;
        int j = year / 100;
        return ((day + 26 * (month + 1) / 10 + k + k / 4 + j / 4 + 5 * j) - 1) % 7;
    }


}

public class MyCalendarGUI extends MyCalendar {

    public MyCalendarGUI(int year, int month, int dayOfMonth) {
        super(year, month, dayOfMonth);
    }

    public void nextDay() {

        // if day is at the end of month, change month and reset day
        if (get(DATE) == daysInMonth()) {
            nextMonth();
        }else {
            set(DATE, get(DATE) + 1);
        }
    }

    public void nextMonth() {
        set(DATE, 1);
        set(MONTH, (get(MONTH) + 1) % 12);

        if (get(MONTH) == 0) {
            set(YEAR, get(YEAR) + 1);
        }
    }

    public void previousMonth(){
        set(DATE, 1);

        int month = get(MONTH) - 1;
        if (month < 0) {
            set(MONTH, 11);
            set(YEAR, get(YEAR) - 1);
        } else {
            set(MONTH, month);
        }

    }

    @Override
    public String toString() {
        return getMonthName() + " " + get(DATE) + ", " + get(YEAR);
    }
}

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.Label;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;
import javafx.scene.paint.Color;
import javafx.stage.Stage;

import java.util.Calendar;

public class Exercise_29 extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception {


        CalendarPane pane = new CalendarPane(9, 2014);

        BorderPane borderPane = new BorderPane(pane);

        Button btPrevious = new Button("Previous");
        btPrevious.setOnAction(e -> pane.previousMonth());

        Button btNext = new Button("Next");
        btNext.setOnAction(e -> pane.nextMonth());

        HBox bottomPane = new HBox(btPrevious, btNext);
        bottomPane.setSpacing(10);
        bottomPane.setPadding(new Insets(5));
        bottomPane.setAlignment(Pos.CENTER);

        borderPane.setBottom(bottomPane);

        Scene scene = new Scene(borderPane, pane.getPrefWidth(), 225);
        primaryStage.setScene(scene);
        primaryStage.setTitle("Calendar");
        primaryStage.show();
    }

    private class CalendarPane extends GridPane {

        MyCalendarGUI cal;
        Label lblMonthYear;

        Label[] lblDayOfWeek = new Label[7];

        private CalendarPane(int month, int year) {

            cal = new MyCalendarGUI(year, --month, 1);

            for (int i = 0; i < lblDayOfWeek.length; i++) {
                lblDayOfWeek[i] = new Label(MyCalendarGUI.getDayOfWeekName(i));
                add(lblDayOfWeek[i], i, 1);
            }

            // set gaps
            setHgap(10);
            setVgap(5);

            setPadding(new Insets(5));
            draw();
        }

        private void draw() {

            getChildren().clear();

            // Title
            lblMonthYear = new Label(cal.getMonthName() + ", " + cal.get(Calendar.YEAR));
            HBox monthYearPane = new HBox(lblMonthYear);
            monthYearPane.setAlignment(Pos.CENTER);
            add(monthYearPane, 0, 0, 7, 1);

            // Days of week name
            for (int i = 0; i < lblDayOfWeek.length; i++) {
                add(lblDayOfWeek[i], i, 1);
            }

            // start day
            int startDay = cal.getStartDay();

            int row = 2;

            // add days prior to current month
            if (startDay > 0) {

                int days = MyCalendar.daysInMonth(
                        cal.get(Calendar.MONTH) - 1, cal.get(Calendar.YEAR));
                days -= startDay -1;

                for (int i = 0; i < startDay; i++) {
                    Label lblDay = new Label(days++ + "");
                    lblDay.setTextFill(Color.grayRgb(10, 0.5));

                    HBox dayHbox = new HBox(lblDay);
                    dayHbox.setAlignment(Pos.CENTER_LEFT);
                    add(dayHbox, i % 7, row);
                }

            }

            // add current days of month
            for (int day = 1; day <= cal.daysInMonth(); day++) {

                Label lblDay = new Label(day + "");
                HBox dayHbox = new HBox(lblDay);
                dayHbox.setAlignment(Pos.CENTER_LEFT);


                add(dayHbox, startDay % 7, row);

                startDay++;
                if (startDay % 7 == 0) {
                    row++;
                }
            }

            // add next month's days
            int day = 1;
            while (startDay % 7 != 0) {
                Label lblDay = new Label(day++ + "");
                HBox dayHbox = new HBox(lblDay);
                dayHbox.setAlignment(Pos.CENTER_LEFT);
                add(dayHbox, startDay % 7, row);
                lblDay.setTextFill(Color.grayRgb(10, 0.5));

                startDay++;
            }

        }

        public void nextMonth() {
            cal.nextMonth();
            draw();
        }

        public void previousMonth() {
            cal.previousMonth();
            draw();
        }
    }
    public static void main(String[] args) {
        Application.launch(args);
    }
}