java画图的有关问题

import java.awt.*;import java.awt.event.*;public class MoveBaseComponents extends Canvas {    static private int x; // 中间变量之横坐标    static private int y; // 中间变量之纵坐标    static private int mouseX; // 鼠标按键横坐标    static private int mouseY; // 鼠标按键纵坐标    static private Point point; // 组件位置    static private Color background = Color.red; // 组件背景颜色    MoveBaseComponents() {        addMouseListener(new Move());        addMouseMotionListener(new Move());        point = new Point(100, 100);        // position();        setBackground(background);        setBounds(50, 50, 50, 50);    }    // 组件定位    public void position() {        setLocation(point);        // repaint();    }    class Move extends MouseAdapter {        public void mousePressed(MouseEvent e) {            mouseX = e.getX();            mouseY = e.getY();        }        public void mouseReleased(MouseEvent e) {            mouseX = 0;            mouseY = 0;        }        public void mouseDragged(MouseEvent e) {            Component com = (Component) e.getSource();            x = com.getX() + e.getX() - mouseX;            y = com.getY() + e.getY() - mouseY;            // 需要做边界限定            point.setLocation(x, y);            position();            // 重合区域变色            Rectangle rectSource = com.getBounds();            Rectangle rectDesc = null;            for (Object obj : Basic.vector) {                if (e.getSource() == obj) {                    continue; // 消除点击后本控件着色                }                rectDesc = ((Component) obj).getBounds();                if (rectSource.intersects(rectDesc)) {                    Rectangle good = rectSource.intersection(rectDesc);//重合区域                    // 新建重合部分                    Graphics pen = com.getGraphics();                    pen.setColor(Color.green);                    pen.fillRect(good.x - rectSource.x, good.y - rectSource.y, good.width, good.height);//                    System.out.println((good.x - rectSource.x) + "," + (good.y - rectSource.y) + "," + good.width + "," + good.height);//                    System.out.println(com);//                    System.out.println(pen);                }            }        }    }    public void mouseMoved(MouseEvent e) {        // System.out.println("move = " + e.getSource());    }}

import java.applet.Applet;import java.awt.Component;public class MyApplet extends Applet {    @Override    public Component add(Component comp) {        Basic.add(comp);        super.add(comp);        return comp;    }    @Override    public void remove(Component comp) {        Basic.remove(comp);        super.remove(comp);    }}

import java.util.Vector;public class Basic {    public static Vector vector = new Vector();    public static void add(Object obj) {        vector.add(obj);    }    public static void remove(Object obj) {        vector.remove(obj);    }}

public class main extends MyApplet {    MoveBaseComponents[] aa = {new MoveBaseComponents(), new MoveBaseComponents(),new MoveBaseComponents(),new MoveBaseComponents()};    public void init() {        for(int i=0 ; i<aa.length ; i++){            add(aa[i]);        }    }}