// this is the basics of gui stuff
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.*;

public class J05GameDisplay extends Component implements ActionListener
{
  private ArrayList<Point> points;
  
  // this is called a constructor (look up the term)
  public J05GameDisplay()
  {
    points = new ArrayList<Point>();
    points.add(new Point(5,5));
    points.add(new Point(20,20));
  }

  public static void main(String[] args)
  {
    J05GameDisplay j05 = new J05GameDisplay();
    JButton myButton = new JButton("Press Me");
    myButton.addActionListener(j05);
    JFrame jf = new JFrame();
    jf.getContentPane().setLayout(new FlowLayout());
    jf.getContentPane().add(j05);
    jf.getContentPane().add(myButton);
    jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    
    jf.pack();
    jf.setVisible(true);
  }	
  
  public void actionPerformed(ActionEvent e) 
  {
    points.add(new Point((int)(Math.random()*400),(int)(Math.random()*400)));
    repaint();
  }

  public Dimension getPreferredSize() 
  {
    return new Dimension(400,400);
  }

  public void paint(Graphics g)
  {
    g.setColor(Color.BLACK);
    g.fillRect(0,0,400,400);
    
    for(int i=0;i<points.size()-1;i++)
    {
      g.setColor(new Color((float)Math.random(),(float)Math.random(),(float)Math.random()));
      g.drawLine(points.get(i).x,points.get(i).y,points.get(i+1).x,points.get(i+1).y);
    }

    g.setColor(Color.RED);
    // note the two types of loop
    for(Point p : points)
    {
      g.drawLine(p.x,p.y,p.x,p.y);
    }
  }
}