modify the program below so that listener classes are derived from the appropria

Question

 modify the program below so that listener classes are derived from the appropriate adapter classes for handling mouse events. also remove all unessecary code  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 (Color.black);       setPreferredSize (new Dimension(400, 200));    }     //-----------------------------------------------------------------    //  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();          repaint();       }        //--------------------------------------------------------------       //  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) {}    } } 

Explanation / Answer

public class RubberLinesPanel extends JPanel
{
private static final long serialVersionUID = 1L;
private Point point1 = null, point2 = null;
private ArrayList<Line2D.Double> lines;
// Constructor: Sets up this panel to listen for mouse events.
public RubberLinesPanel()
{
lines = new ArrayList<Line2D.Double>();
LineListener listener = new LineListener();
addMouseListener(listener);
addMouseMotionListener(listener);
setBackground(Color.black);
setPreferredSize(new Dimension(400, 200));
}
// 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);
if (point2 != null)
{
page.setColor(Color.GREEN);
page.drawLine(point1.x, point1.y, point2.x, point2.y);
}
page.setColor(Color.yellow);
for (int i = 0; i < lines.size(); i++)
{
if (lines.get(i) != null)
{
page.drawLine((int)lines.get(i).getX1(), (int)lines.get(i).getY1(),(int)lines.get(i).getX2(), (int)lines.get(i).getY2());
}
}
}
// 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();
repaint();
}
// Provide empty definitions for unused event methods.
public void mouseClicked(MouseEvent event)
{
}
public void mouseReleased(MouseEvent event)
{
Line2D.Double newLine = new Line2D.Double(point1, point2);
lines.add(newLine);
point2 = null;
repaint();
}
public void mouseEntered(MouseEvent event)
{
}
public void mouseExited(MouseEvent event)
{
}
public void mouseMoved(MouseEvent event)
{
}
}
// Creates and displays the application frame.
public static void main (String[] args)
{
JFrame frame = new JFrame ("Rubber Lines");
frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add (new RubberLinesPanel());
frame.pack();
frame.setVisible(true);
}
}

Related Questions

Navigate

• Browse (All)
• Browse M
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.