MouseTracker.java

// Fig. 12.28-29: MouseTracker
// Mouse event handling.
import java.awt.Color;
import java.awt.BorderLayout;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

class MouseTrackerFrame extends JFrame
{
   private final JPanel mousePanel; // panel in which mouse events occur
   private final JLabel statusBar; // displays event information

   // MouseTrackerFrame constructor sets up GUI and 
   // registers mouse event handlers
   public MouseTrackerFrame()
   {
      super("Demonstrating Mouse Events");

      mousePanel = new JPanel(); 
      mousePanel.setBackground(Color.WHITE); 
      add(mousePanel, BorderLayout.CENTER); // add panel to JFrame

      statusBar = new JLabel("Mouse outside JPanel"); 
      add(statusBar, BorderLayout.SOUTH); // add label to JFrame

      // create and register listener for mouse and mouse motion events
      MouseHandler handler = new MouseHandler(); 
      mousePanel.addMouseListener(handler); 
      mousePanel.addMouseMotionListener(handler); 
   } 

   private class MouseHandler implements MouseListener, 
      MouseMotionListener 
   {
      // MouseListener event handlers
      // handle event when mouse released immediately after press
      @Override
      public void mouseClicked(MouseEvent event)
      {
         statusBar.setText(String.format("Clicked at [%d, %d]", 
            event.getX(), event.getY()));
      } 

      // handle event when mouse pressed
      @Override
      public void mousePressed(MouseEvent event)
      {
         statusBar.setText(String.format("Pressed at [%d, %d]", 
            event.getX(), event.getY()));
      }

      // handle event when mouse released 
      @Override
      public void mouseReleased(MouseEvent event)
      {
         statusBar.setText(String.format("Released at [%d, %d]", 
            event.getX(), event.getY()));
      }

      // handle event when mouse enters area
      @Override
      public void mouseEntered(MouseEvent event)
      {
         statusBar.setText(String.format("Mouse entered at [%d, %d]", 
            event.getX(), event.getY()));
         mousePanel.setBackground(Color.GREEN);
      }

      // handle event when mouse exits area
      @Override
      public void mouseExited(MouseEvent event)
      {
         statusBar.setText("Mouse outside JPanel");
         mousePanel.setBackground(Color.WHITE);
      }

      // MouseMotionListener event handlers
      // handle event when user drags mouse with button pressed
      @Override
      public void mouseDragged(MouseEvent event)
      {
         statusBar.setText(String.format("Dragged at [%d, %d]", 
            event.getX(), event.getY()));
      } 

      // handle event when user moves mouse
      @Override
      public void mouseMoved(MouseEvent event)
      {
         statusBar.setText(String.format("Moved at [%d, %d]", 
            event.getX(), event.getY()));
      } 
   } // end inner class MouseHandler
} // end class MouseTrackerFrame

public class MouseTracker 
{
   public static void main(String[] args)
   { 
      MouseTrackerFrame mouseTrackerFrame = new MouseTrackerFrame(); 
      mouseTrackerFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      mouseTrackerFrame.setSize(300, 100); 
      mouseTrackerFrame.setVisible(true); 
   } 
} // end class MouseTracker