问题详情

阅读以下说明和JAVA 2代码，填入(n)处。
[说明]
以下程序实现了利用鼠标任意移动圆形的位置，仔细阅读代码和相关注释，将程序补充完整。
[代码6-1]
import java.awt.*;
import java.awt.event.*;
public class CIUSAMPLE extends Frame. implements MouseMotionListener, MouseListener
{
static CIUSAMPLE frm=new CIUSAMPLE ();
int x=70,y=60,posX=70,posY=60,dx,dy;
public static void main (String args[])
{
frm.setTitle ("Dragging a circle");
frm.setSize (200,150);
(1)
ffm.addMouseMotionListener (frm);
frm.setVisible (true);
}
public void mousePressed (MouseEvent e)
{
(2)
dy=e.getY () -posY;
}
public void mouseDragged (MouseEvent e)
{
(3)
y=e.getY () -dy;
if(dx＞0&&dx＜50&&dy＞0&&dy＜50) //如果指针落在正方形区域内
{
Graphicsg=getGraphics ();
(4)
}
}
public void paint (Graphics g)
{
g.setColor (Color.pink); //设置绘图颜色为粉红
g.fillOval(x,y,50,50); //以基准点为图形在左上角绘出圆形
(5)
posY=y；
}
public void mouseMoved (MouseEvent e) {}
public void mouseReleased (MouseEvent e) {}
public void mouseEntered (MouseEvent e) {}
public void mouseExited (MouseEvent e) {}
public void mouseClicked (MouseEvent e) {}
}请帮忙给出正确答案和分析，谢谢！