Swing Text

import java.awt.*;
import javax.swing.*;
import java.awt.Event.*;
import java.awt.geom.*;
import javax.swing.event.*;

public class TextTest {
    public static void main(String[] args){
        new TextFrame();
    }

}
class TextFrame extends JFrame {
    private ClockPanel clock;
    private JTextField hourField;
    private JTextField minuteField;
    public TextFrame(){
        
        clock = new ClockPanel();
        add(clock,BorderLayout.CENTER);
        
        JPanel input = new JPanel();
        add(input,BorderLayout.SOUTH);
        
        hourField = new JTextField("3",2);
        minuteField = new JTextField("0",2);
        ClockListener listener = new ClockListener(); 
        hourField.getDocument().addDocumentListener(listener);
        minuteField.getDocument().addDocumentListener(listener);
        
        input.add(new JLabel("Hour:"));
        input.add(hourField);
        input.add(new JLabel("Minute:"));
        input.add(minuteField);
        
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocation(300,300);
        setSize(400,450);
        setVisible(true);
        
        
    }
    private class ClockListener implements DocumentListener {
        public void insertUpdate(DocumentEvent e){
            setClock();
        }
        public void removeUpdate(DocumentEvent e) {
            setClock();
        }
        public void changedUpdate(DocumentEvent e){
            setClock();
        }
    }
    private void setClock(){
        int hour = 0;
        int min = 0;
        try {
        hour = Integer.parseInt(hourField.getText());
        min = Integer.parseInt(minuteField.getText());
        } catch (NumberFormatException e){ return;}
        clock.setTime(hour,min);
    }
}
class ClockPanel extends JPanel {
    private int hour;
    private int minute;
    public ClockPanel(){
        this.hour = 3;
        this.minute = 0;
    }
    public void paintComponent(Graphics g ) {
        double hourangle;
        double minuteangle;
        System.out.println("draw"+hour+":"+minute);
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g;
    
        
        Ellipse2D circle = new Ellipse2D.Double(0, 0, 380, 380);
        g2.draw(circle);
        //注意int计算,类型转换问题
        hourangle = (60.0*hour+minute)/(12*60)*2*(Math.PI);
        minuteangle = minute/60.0*2*(Math.PI);
        //System.out.println("angle"+hourangle+":"+minuteangle);
        Point2D hourpoint = new Point2D.Double(190+100*Math.sin(hourangle),190-100*Math.cos(hourangle));
        Point2D minutepoint = new Point2D.Double(190+180*Math.sin(minuteangle),190-180*Math.cos(minuteangle));
        Point2D center = new Point2D.Double(190,190);
        
        g2.draw(new Line2D.Double(center, hourpoint));
        g2.draw(new Line2D.Double(center, minutepoint));
    }
    public void setTime(int hour,int minute){
        this.hour = hour;
        this.minute = minute;
        repaint();
    }
}