JavaFX GridPane layout calendar

import java.util.Calendar;
import java.util.GregorianCalendar;

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;
import javafx.scene.paint.Color;
import javafx.scene.text.Text;
import javafx.stage.Stage;

class GraphicalCalendar extends BorderPane {
   private Calendar currentMonth;

   public GraphicalCalendar() {
      currentMonth = new GregorianCalendar();
      currentMonth.set(Calendar.DAY_OF_MONTH, 1);

      drawCalendar();/*from ww  w. j  ava2s  . c  o  m*/
   }

   private void drawCalendar() {
      drawHeader();
      drawBody();
      drawFooter();
   }

   private void drawHeader() {
      String monthString = getMonthName(currentMonth.get(Calendar.MONTH));
      String yearString = String.valueOf(currentMonth.get(Calendar.YEAR));
      Text tHeader = new Text(monthString + ", " + yearString);

      setTop(tHeader);
      setAlignment(tHeader, Pos.CENTER);
      setMargin(tHeader, new Insets(15));
   }

   private void drawBody() {
      GridPane gpBody = new GridPane();
      gpBody.setHgap(10);
      gpBody.setVgap(10);
      gpBody.setAlignment(Pos.CENTER);
      gpBody.setMinHeight(300);

      // Draw days of the week
      for (int day = 1; day <= 7; day++) {
         Text tDayName = new Text(getDayName(day));
         gpBody.add(tDayName, day - 1, 0);
      }

      // Draw days in month
      int currentDay = currentMonth.get(Calendar.DAY_OF_MONTH);
      int daysInMonth = currentMonth.getActualMaximum(Calendar.DAY_OF_MONTH);
      int dayOfWeek = currentMonth.get(Calendar.DAY_OF_WEEK);
      int row = 1;
      for (int i = currentDay; i <= daysInMonth; i++) {
         if (dayOfWeek == 8) {
            dayOfWeek = 1;
            row++;
         }
         Text tDate = new Text(String.valueOf(currentDay));
         gpBody.add(tDate, dayOfWeek - 1, row);
         currentDay++;
         dayOfWeek++;
      }

      // Draw previous month days
      dayOfWeek = currentMonth.get(Calendar.DAY_OF_WEEK);
      if (currentDay != 1) {
         Calendar prevMonth = getPreviousMonth(currentMonth);
         int daysInPrevMonth = prevMonth.getActualMaximum(Calendar.DAY_OF_MONTH);
         for (int i = dayOfWeek - 2; i >= 0; i--) {
            Text tDate = new Text(String.valueOf(daysInPrevMonth));
            tDate.setFill(Color.GRAY);
            gpBody.add(tDate, i, 1);
            daysInPrevMonth--;
         }
      }

      // Draw next month days
      currentMonth.set(Calendar.DAY_OF_MONTH, currentMonth.getActualMaximum(Calendar.DAY_OF_MONTH));
      dayOfWeek = currentMonth.get(Calendar.DAY_OF_WEEK);
      if (dayOfWeek != 7) {
         int day = 1;
         for (int i = dayOfWeek; i < 7; i++) {
            Text tDate = new Text(String.valueOf(day));
            tDate.setFill(Color.GRAY);
            gpBody.add(tDate, i, row);
            day++;
         }
      }

      setCenter(gpBody);
      setMargin(gpBody, new Insets(30));
   }

   private void drawFooter() {
      Button btPrev = new Button("Prev");
      Button btNext = new Button("Next");

      btPrev.setOnAction(e -> previous());
      btNext.setOnAction(e -> next());

      HBox hbFooter = new HBox(10);
      hbFooter.getChildren().addAll(btPrev, btNext);
      hbFooter.setAlignment(Pos.CENTER);

      setBottom(hbFooter);
      setMargin(hbFooter, new Insets(15));
   }

   private void previous() {
      getChildren().clear();
      currentMonth = getPreviousMonth(currentMonth);
      drawCalendar();
   }

   private void next() {
      getChildren().clear();
      currentMonth = getNextMonth(currentMonth);
      drawCalendar();
   }

   private GregorianCalendar getPreviousMonth(Calendar cal) {
      int cMonth = cal.get(Calendar.MONTH);
      int pMonth = cMonth == 0 ? 11 : cMonth - 1;
      int pYear = cMonth == 0 ? cal.get(Calendar.YEAR) - 1 : cal.get(Calendar.YEAR);
      return new GregorianCalendar(pYear, pMonth, 1);
   }

   private GregorianCalendar getNextMonth(Calendar cal) {
      int cMonth = cal.get(Calendar.MONTH);
      int pMonth = cMonth == 11 ? 0 : cMonth + 1;
      int pYear = cMonth == 11 ? cal.get(Calendar.YEAR) + 1 : cal.get(Calendar.YEAR);
      return new GregorianCalendar(pYear, pMonth, 1);
   }

   private String getDayName(int n) {
      StringBuilder sb = new StringBuilder();
      switch (n) {
      case 1:
         sb.append("Sunday");
         break;
      case 2:
         sb.append("Monday");
         break;
      case 3:
         sb.append("Tuesday");
         break;
      case 4:
         sb.append("Wednesday");
         break;
      case 5:
         sb.append("Thursday");
         break;
      case 6:
         sb.append("Friday");
         break;
      case 7:
         sb.append("Saturday");
      }
      return sb.toString();
   }

   private String getMonthName(int n) {
      String[] monthNames = { "January", "February", "March", "April", "May", "June", "July", "August", "September",
            "October", "November", "December" };
      return monthNames[n];
   }
}

public class Main extends Application {
   @Override
   public void start(Stage primaryStage) {
      GraphicalCalendar gc = new GraphicalCalendar();

      Scene scene = new Scene(gc);
      primaryStage.setTitle("java2s.com");
      primaryStage.setScene(scene);
      primaryStage.show();
   }

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