LAB ACTIVITY 3I

Learning Outcomes

  By the end of this lab, students should be able to :

• • Write Java programs using Event Handling

  • Write Java programs using Event Handling with GUI Components

Hardware/ Software : Personal Computer, Java Development Kit version X.x.x., NetBeans IDE 12.0

LAB ACTIVITY 3I

Activity Outcome: Student know how to create event handling program for MouseMotionListener.

CREATE New Project name as Painter

i. Type the following code:

package painter;

import java.awt.*;

import javax.swing.*;

public class Painter extends JFrame{

    private int pointCount = 0;

    private Point points[] = new Point[1000];

    public Painter(){

        super("A simple paint program");

        getContentPane().add(new JLabel("Drag the mouse to draw"),

        BorderLayout.SOUTH);

        setSize(300, 150);

        setVisible(true);                                

    }

    public static void main(String args[]){

        Painter application = new Painter();

        application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 

    } 

}

ii. Declaration of the event handler class

a) Add package java.awt.event.*;  

      b) addMouseMotionListener

 addMouseMotionListener(

        new MouseMotionAdapter()

        {

                public void mouseDragged(MouseEvent event)

                {

                                if (pointCount < points.length)

                                {

                                        points[pointCount] = event.getPoint();

                                        ++pointCount;

                                        repaint();

                                }

                }

        }  );

example image:

iii. Create effect public class using by mouse 

public void paint(Graphics g){

        super.paint(g);

        for(int i=0; i< points.length && points[i] != null; i++)

        g.fillOval(points[i].x, points[i].y, 4, 4);

    }

example image:

FULL CODE & EXAMPLE GUI OUTPUT :

package painter;

import java.awt.*;

import javax.swing.*;

import java.awt.event.*;

public class Painter extends JFrame{

    private int pointCount = 0;

    private Point points[] = new Point[1000];

    public Painter(){

        super("A simple paint program");

        getContentPane().add(new JLabel("Drag the mouse to draw"),

        BorderLayout.SOUTH);

addMouseMotionListener(

        new MouseMotionAdapter()

        {

                public void mouseDragged(MouseEvent event)

                {

                                if (pointCount < points.length)

                                {

                                        points[pointCount] = event.getPoint();

                                        ++pointCount;

                                        repaint();

                                }

                }

        }  );   

        setSize(300, 150);

        setVisible(true);                                

    }

    public void paint(Graphics g){

        super.paint(g);

        for(int i=0; i< points.length && points[i] != null; i++)

        g.fillOval(points[i].x, points[i].y, 4, 4);

    }

    public static void main(String args[]){

        Painter application = new Painter();

        application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 

    } 

}

OUTPUT :   (Move and Click mouse on Frame to show graphic line)