这个程序为什么会报这两个警告!!!

第一个程序:
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.util.*;public class Paint extends Applet {
    Vector v=new Vector();
    /** Creates a new instance of Paint */
    public Paint() {
    }
    public void paint(Graphics g){
        int[] x,y;
        x=new int[v.size()];
        y=new int[v.size()];
        for(int i=0;i<v.size();i++){
            Point p=(Point)v.get(i);
            x[i]=p.x;
            y[i]=p.y;            
        }
        g.drawPolyline(x,y,v.size());
    }
    public void init(){
        
        addMouseMotionListener(
                new MouseMotionAdapter(){
                    public void mouseDragged(MouseEvent e){
                        Point p=e.getPoint();
                        v.add(p);
                        repaint();
                    }                    
        });
    }
    
    /**
     * @param args the command line arguments
     */
       public static void main(String[] args) {
        // TODO code application logic here
        Frame win=new Frame("Paint");
        Paint p=new Paint();
        win.add(p);
        p.init();
        win.setSize(600,360);
        win.setVisible(true);
        win.addWindowListener(
                new WindowAdapter(){
                    public void windowClosing(WindowEvent e){
                        System.exit(0);
                    }
        });
    }
    
}
编译的时候会发出两个警告,第一个是v.add(p)(调用未经检查),第二个是类Paint中没有serialVersionUid的定义。请问这两个警告如何解决？