求一个JAVA小程序

//ClockAnimation.java
package p1;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class ClockAnimation extends JFrame
{
	private StillClock clock=new StillClock();
	public ClockAnimation()
	{
		add(clock);
		Timer timer=new Timer(1000,new TimerListener());
		timer.start();
	}
	private class TimerListener implements ActionListener
	{
		public void actionPerformed(ActionEvent e)
		{
			clock.setCurrentTime();
			clock.repaint();
		}
	}
	public static void main(String[] args) 
	{
		JFrame frame=new ClockAnimation();
		frame.setTitle("DisplayClock");
		frame.setSize(400,400);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setLocationRelativeTo(null);
		frame.setVisible(true);
	}
}

//StillClock.java
package p1;
import java.util.*;
import javax.swing.*;
import java.awt.*;
public class StillClock extends JPanel
{
	private int hour;
	private int minute;
	private int second;
	public StillClock()
	{
		setCurrentTime();
	}
	public StillClock(int hour,int minute,int second)
	{
		this.hour=hour;
		this.minute=minute;
		this.second=second;
	}
	public int getHour()
	{
		return hour;
	}
	public void setHour(int hour)
	{
		this.hour=hour;
		repaint();
	}
	public int getMinute()
	{
		return minute;
	}
	public void setMinute(int minute)
	{
		this.minute=minute;
		repaint();
	}
	public int getSecond()
	{
		return second;
	}
	public void setSecond(int second)
	{
		this.second=second;
		repaint();
	}
	protected void paintComponent(Graphics g)
	{
		super.paintComponent(g);
		int clockRadius=(int)(Math.min(getWidth(), getHeight())*0.3);
		int xCenter=getWidth()/2;
		int yCenter=getHeight()/2;
		g.setColor(Color.black);
		g.drawRect(20, 20, getWidth()-70,getHeight()-70);
		g.setColor(Color.BLACK);
		g.drawOval(xCenter-clockRadius, yCenter-clockRadius, 2*clockRadius,2*clockRadius);
		g.drawString("12", xCenter-5, yCenter-clockRadius+12);
		g.drawString("9", xCenter-clockRadius+3, yCenter+5);
		g.drawString("3", xCenter+clockRadius-10,yCenter+3);
		g.drawString("6", xCenter-3, yCenter+clockRadius-3);
		int sLength=(int)(clockRadius*0.8);
		int xSecond=(int)(xCenter+sLength*Math.sin(second*(2*Math.PI/60)));
		int ySecond=(int)(yCenter-sLength*Math.cos(second*(2*Math.PI/60)));
		g.setColor(Color.red);
		g.drawLine(xCenter, yCenter, xSecond, ySecond);
		int mLength=(int)(clockRadius*0.65);
		int xMinute=(int)(xCenter+mLength*Math.sin(minute*(2*Math.PI/60)));
		int yMinute=(int)(yCenter-mLength*Math.cos(minute*(2*Math.PI/60)));
		g.setColor(Color.blue);
		g.drawLine(xCenter, yCenter, xMinute, yMinute);
		int hLength=(int)(clockRadius*0.5);
		int xHour=(int)(xCenter+hLength*Math.sin((hour%12+minute/60.0)*(2*Math.PI/12)));
		int yHour=(int)(yCenter-hLength*Math.cos((hour%12+minute/60.0)*(2*Math.PI/12)));
		g.setColor(Color.green);
		g.drawLine(xCenter, yCenter, xHour, yHour);
		g.setColor(Color.black);
		g.drawRect(20, getHeight()-35, getWidth()-70,30);
		g.drawString("Hour", 60, getHeight()-15);
		g.setColor(Color.white);
		g.fillRect(90, getHeight()-25, 30,15);
		g.setColor(Color.black);
		g.drawString(""+hour, 95,getHeight()-15 );
		g.drawString("Minute", 135, getHeight()-15);
		g.setColor(Color.white);
		g.fillRect(180, getHeight()-25, 30,15);
		g.setColor(Color.black);
		g.drawString(""+minute, 190,getHeight()-15 );
		g.drawString("Second", 230, getHeight()-15);
		g.setColor(Color.white);
		g.fillRect(280, getHeight()-25, 30,15);
		g.setColor(Color.black);
		g.drawString(""+second, 290,getHeight()-15 );
		
	}
	public void setCurrentTime()
	{
		Calendar calendar=new GregorianCalendar();
		this.hour=calendar.get(Calendar.HOUR_OF_DAY);
		this.minute=calendar.get(Calendar.MINUTE);
		this.second=calendar.get(Calendar.SECOND);
	}
	public Dimension getPreferredSize()
	{
		return new Dimension(200,200);
	}
}//这是我前段时间写的一个时钟动态显示的程序！不懂的地方就直接追问吧！

图形界面，自己继续

第1个，可以这样
public class App_555 { class Person{ public String name; public Person (String name){ this.name=name; System.out.println("the Person of Java"); } } class Student extends Person{ int age; public Student(String name,int age){ super(name); this.age=age; } public void show(){ System.out.println("the Student of person"); } } public static void main(String[] args) { new App_555().test(); } public void test() { Person per=new Person(" m l z"); Student stu=new Student("m l z", 14); stu.show(); }}