I have this program "RubberLines" that I need to make remember all the lines that users have put in. It has been suggested that I use an ArrayList to store where the points where located and have them draw out each time a new line is put in. I'm not sure how to  store the points of a line in an Array list.

import javax.swing.JPanel;
import java.awt.*;
import java.awt.event.*;

public class RubberLinesPanel extends JPanel
   private Point point1 = null, point2 = null;

   //  Constructor: Sets up this panel to listen for mouse events.
   public RubberLinesPanel()
      LineListener listener = new LineListener();
      addMouseListener (listener);
      addMouseMotionListener (listener);

      setBackground (;
      setPreferredSize (new Dimension(400, 400));

   //  Draws the current line from the intial mouse-pressed point to
   //  the current position of the mouse.
   public void paintComponent (Graphics page)
      super.paintComponent (page);

      page.setColor (Color.yellow);
      if (point1 != null && point2 != null)
         page.drawLine (point1.x, point1.y, point2.x, point2.y);

   //  Represents the listener for all mouse events.
   private class LineListener implements MouseListener,MouseMotionListener
      //  Captures the initial position at which the mouse button is
      //  pressed.
      public void mousePressed (MouseEvent event)
         point1 = event.getPoint();

      //  Gets the current position of the mouse as it is dragged and
      //  redraws the line to create the rubberband effect.
      public void mouseDragged (MouseEvent event)
         point2 = event.getPoint();

      //  Provide empty definitions for unused event methods.
      public void mouseClicked (MouseEvent event) {}
      public void mouseReleased (MouseEvent event) {}
      public void mouseEntered (MouseEvent event) {}
      public void mouseExited (MouseEvent event) {}
      public void mouseMoved (MouseEvent event) {}
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1. Store the two points individually, so for every line you would add two points to list.


2. Add each line has 2 element array of points

lines.add(new Point[] { point1, point2 });

3. Use the java.awt.geom.Line2D.float class

lines.add(new Line2D.Float(point1, point2));

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