Adapter class used to implement event handlers. - Java Swing

Java examples for Swing:Mouse Event

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Description

Adapter class used to implement event handlers.

Demo Code

import java.awt.BorderLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import java.awt.Point;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import java.util.ArrayList;
import javax.swing.JPanel;

class PaintPanel extends JPanel 
{
   // list Point references
   private final ArrayList<Point> points = new ArrayList<>(); 

   // set up GUI and register mouse event handler
   public PaintPanel()
   {// w ww  . j a v  a2s. c  o  m
      // handle frame mouse motion event
      addMouseMotionListener(
         new MouseMotionAdapter() // anonymous inner class
         {  
            // store drag coordinates and repaint
            @Override
            public void mouseDragged(MouseEvent event)
            {
               points.add(event.getPoint());
               repaint(); // repaint JFrame
            } 
         } 
      ); 
   }

   // draw ovals in a 4-by-4 bounding box at specified locations on window
   @Override
   public void paintComponent(Graphics g)
   {
      super.paintComponent(g); // clears drawing area

      // draw all 
      for (Point point : points){
         g.fillOval(point.x, point.y, 4, 4);
      }
   } 
}

public class Main
{
   public static void main(String[] args)
   { 
      JFrame application = new JFrame("A simple paint program");

      PaintPanel paintPanel = new PaintPanel(); 
      application.add(paintPanel, BorderLayout.CENTER); 
      
      // create a label and place it in SOUTH of BorderLayout
      application.add(new JLabel("Drag the mouse to draw"), 
         BorderLayout.SOUTH);

      application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      application.setSize(400, 200); 
      application.setVisible(true); 
   } 
}

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