Poligono cliccando sui vertici

import java.awt.event.*;
import java .awt.*;
import javax.swing.*;
public class Retta extends JPanel implements MouseListener {
private int x1;
private int y1;
private int x2;
private int y2;
private int conta=0;
private int i=0;
private int[] ascisse=new int[50];
private int[] ordinate=new int[50];
private int numero=5;
public Retta(){
addMouseListener(this);
}
@Override public void mouseClicked(MouseEvent e){

}
@Override public void mouseEntered(MouseEvent e){

}
@Override public void mouseExited(MouseEvent e){

}
@Override public void mousePressed(MouseEvent e){
ascisse[i]=e.getX();
ordinate[i]=e.getY();
i++;
if(i>numero-1){
i=0;
repaint();
}
}
@Override public void mouseReleased(MouseEvent e){
}
@Override public void paintComponent(Graphics g){
int j=0;
g.setColor(Color.red);
for(j=0;j g.drawLine(ascisse[j], ordinate[j], ascisse[j+1], ordinate[j+1]);
}
g.drawLine(ascisse[0], ordinate[0], ascisse[j], ordinate[j]);
}
}



import java.awt.*;
import javax.swing.*;
public class TestaRetta {
public static void main(String Args[]){
Retta r1=new Retta();
JFrame f1=new JFrame("Retta");
f1.setSize(500,500);
f1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f1.add(BorderLayout.CENTER,r1);
f1.setVisible(true);
}
}