import javax.swing.*;
import java.awt.*;
import java.util.*;

public class CalendarTest extends JPanel {
    public CalendarTest() {
        setPreferredSize(new Dimension(250, 100));
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Calendar now = Calendar.getInstance();
        int day  = now.get(Calendar.DAY_OF_WEEK);
        int hour = now.get(Calendar.HOUR_OF_DAY);
        int min  = now.get(Calendar.MINUTE);
        if (day == Calendar.SUNDAY) {
            g.setColor(Color.RED);
            g.drawString("今日は日曜日です。", 30, 25);
        }
        if (hour < 12) {
            g.drawString("おはようございます。", 30, 75);
        } else if (hour < 18) {
            g.drawString("こんにちは。", 30, 75);
        } else {
            g.drawString("こんばんは。", 30, 75);
        }
        g.drawString("ただいま " + hour + "時 "
                      + min + "分です。", 30, 50);
        // g.drawString(String.format(
        //    "ただいま %d時 %d分です。", hour, min),
        //              30, 50);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            JFrame frame = new JFrame("");
            frame.add(new CalendarTest());
            frame.pack();
            frame.setVisible(true);
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        });
    }
}