java - JTextArea を使用したカレンダー

Question

JTextArea を使用して Java で予定カレンダーを作成しようとしています。任意の日を左クリックすると、予定を書き込むための独自の編集可能な JTextArea が表示されます。毎日の部分を気にせずに、新しいテキストエリアをポップアップさせるのに助けが必要です。docs.oracle の内容を読みましたが、これまでの試行で不明なソース エラーが発生しました。

import java.awt.*;
import java.awt.event.*;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.awt.BorderLayout;
import javax.swing.*;

@SuppressWarnings("serial")
public class GUICal extends JFrame{
int month = java.util.Calendar.getInstance().get(java.util.Calendar.MONTH);
int year = java.util.Calendar.getInstance().get(java.util.Calendar.YEAR);;
JLabel l = new JLabel("", JLabel.CENTER);
String day = "";
JDialog d;
JButton[] button = new JButton[49];
static GUICal _gui;
public GUICal() {

    JFrame jpf = new JFrame();
    jpf.setDefaultCloseOperation(EXIT_ON_CLOSE);
    d = new JDialog();
    d.setModal(true);
    String[] header = { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" };
    JPanel p1 = new JPanel(new GridLayout(7, 7));
    p1.setPreferredSize(new Dimension(430, 120));

    for (int x = 0; x < button.length; x++) {
        final int selection = x;
        button[x] = new JButton();
        button[x].setFocusPainted(false);
        button[x].setBackground(Color.green);
        if (x > 6) {
            button[x].addMouseListener(new MouseListener() {
                public void mouseClicked(MouseEvent ae) {
                    day = button[selection].getActionCommand();
                    switch(ae.getModifiers()) {
                    case InputEvent.BUTTON1_MASK: {//left-clicker

                        break;
                      }
                    case InputEvent.BUTTON3_MASK: {//right-clicker

                      break;
                      }
                    }   
                }
                public void mouseEntered(MouseEvent arg0) {}
                public void mouseExited(MouseEvent arg0) {}
                public void mousePressed(MouseEvent arg0) {}
                public void mouseReleased(MouseEvent arg0) {}
            });

        }

        if (x < 7) {
            button[x].setText(header[x]);
            button[x].setForeground(Color.red);
        }
        p1.add(button[x]);

    }

    JPanel p2 = new JPanel(new GridLayout(1, 3));
    JButton previous = new JButton("<< Prior");
    previous.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent ae) {
            month--;
            displayDate();
        }
    });
    p2.add(previous);
    p2.add(l);
    JButton next = new JButton("Next >>");
    next.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent ae) {
            month++;
            displayDate();
        }
    });
    p2.add(next);
    d.add(p1, BorderLayout.CENTER);
    d.add(p2, BorderLayout.SOUTH);
    d.pack();
    d.setLocationRelativeTo(jpf);
    displayDate();
    d.setVisible(true);
}

public void displayDate() {
    for (int x = 7; x < button.length; x++)
        button[x].setText("");
    java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat(
            "MMMM yyyy");
    java.util.Calendar cal = java.util.Calendar.getInstance();
    cal.set(year, month, 1);
    int dayOfWeek = cal.get(java.util.Calendar.DAY_OF_WEEK);
    int daysInMonth = cal.getActualMaximum(java.util.Calendar.DAY_OF_MONTH);
    for (int x = 6 + dayOfWeek, day = 1; day <= daysInMonth; x++, day++) {
        button[x].setText("" + day);

        d.setTitle(sdf.format(cal.getTime()));
        for (int y = 7; y < button.length; y++) {
            String str = button[x].getText();
            int m = Integer.parseInt(str);
            SimpleDateFormat fm = new SimpleDateFormat("MMMM yyyy");
            String dfm = fm.format(new Date());
            SimpleDateFormat format = new SimpleDateFormat("dd");
            String date = format.format(new Date());

            int n = Integer.parseInt(date);
            if ((m < n) && (dfm.equals(l.getText())))
                button[x].setEnabled(false);

        }
    }
}
public String setPickedDate() {
    if (day.equals(""))
        return day;
    java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat(
            "  dd/MM/yyyy   hh:mm:ss");
    java.util.Calendar cal = java.util.Calendar.getInstance();
    cal.set(year, month, Integer.parseInt(day));
    return sdf.format(cal.getTime());
}

public static void main(String[] args) {
_gui = new GUICal();
}

}