Java Applet Basics & Event Handling

 

JAVA

Java Applet Basics & Event Handling

 

Fill in the blanks

 

1.A reference to an applet is embedded in a Web page using a special HTML tag

2.Applet can’t communicate with a server other than the one that had originally stored the applet.[T/F]. True.

3.Write a package for applet import java.awt.*;

4.Write a method to print string in applet drawString()

5. Applets cannot make network connection exception to the server host from which it originated.[True/False]. True

6.The paint() method is called each time your applet’s output must be redrawn.

7.Write a method to draw a line  drawLine()

8.To draw rectangle what method is used drawRect()

9.Write a method for polygon drawPolygon()

10. Write a method for filling oval fillOval()

11. Write a method for  To printing a text in red color  setColor(Color.red)

12. ActionEvent is used for when a button is pressed.

13.KeyEvent is used to generate  when input is received from the keyboard.

14.MouseEvent is used to generate when the mouse is dragged ,moved,clicked,pressed or released.

15.Adapter class is to simplify the creation of event  handler in certain situations.

 

Answer the Following Questions

                                                                (4 marks)

1.   Write a program to print Rectangle using Applet

import java.awt.*;

import java.applet.*;

/*

<applet code="Rectangles" width=300 height=200>

</applet>

*/

public class Rectangles extends Applet{

public void paint(Graphics g){

g.drawRect(10,10,60,50);

g.fillRect(100,10,60,50);

g.drawRoundRect(190,10,60,50,15,15);

g.fillRoundRect(70,90,140,100,30,40);

}

}

2.   Write a program to print Polygon using Applet

import java.awt.*;

import java.applet.*;

/*

<applet code="HourGlass" width=230 height=210>

</applet>

*/

public class HourGlass extends Applet{

public void paint(Graphics g){

int xpoints[]={30,200,30,200,30};

int ypoints[]={30,30,200,200,30};

g.drawPolygon(xpoints,ypoints,5);

}

}

3.   Write a program to print Oval using Applet

File name: Ellipses.java

import java.awt.*;

import java.applet.*;

/*

<applet code="Ellipses" width=300 height=200>

</applet>

*/

public class Ellipses extends Applet{

public void paint(Graphics g){

g.drawOval(10,10,50,50);

g.fillOval(100,10,75,50);

g.drawOval(190,10,90,30);

g.fillOval(70,90,140,100);

}

}

4.   Write a program to print Lamp using Applet

File name: Lamp.java

import java.awt.*;

/*

<applet code="Lamp" width=300 height=200>

</applet>

*/

public class Lamp extends java.applet.Applet{

public void paint(Graphics g){

g.fillRect(0,250,290,290);

g.drawLine(125,250,125,160);

g.drawLine(175,250,175,160);

g.drawArc(85,157,130,50,-65,312);

g.drawArc(85,87,130,50,62,58);

g.drawLine(85,177,119,89);

g.drawLine(215,177,181,89);

g.fillArc(78,120,40,40,63,-174);

g.fillOval(120,96,40,40);

g.fillArc(173,100,40,40,110,180);

}

}

 

5.   Write a program to print text using color

Output :

Hello World

Hello World

Hello World

File name: ColorAppletDemo.java

import java.awt.*;

import java.awt.Font;

import java.applet.*;

/*

<applet code=ColorAppletDemo width=300 height=300>

</applet>

*/

public class ColorAppletDemo extends Applet{

public void paint(Graphics g){

Font f=new Font("TimesRoman",Font.BOLD,20);

Font f1=new Font("Courier",Font.ITALIC,20);

Font f2=new Font("Helevitica",Font.PLAIN,20);

g.setColor(Color.red);

g.setFont(f);

g.drawString("Hello World",30,30);

g.setColor(Color.blue);

g.setFont(f1);

g.drawString("Hello World ",30,70);

g.setColor(Color.pink);

g.setFont(f2);

g.drawString("Hello World ",30,110);

}

}

 

6.Write a program for KeyEvent Handler

import java.awt.*;

import java.awt.event.*;

import java.applet.*;

/*

<applet code="SimpleKey" width=300 height=100>

</applet>

*/

public class SimpleKey extends Applet implements KeyListener{

String msg="";

int X=10,Y=20;

public void init(){

addKeyListener(this);

requestFocus();

}

public void keyPressed(KeyEvent ke){

showStatus("Key Down");

}

public void keyReleased(KeyEvent ke){

showStatus("Key Up");

}

public void keyTyped(KeyEvent ke){

msg+=ke.getKeyChar();

repaint();

}

public void paint(Graphics g){

g.drawString(msg,X,Y);

}

}

 

Answer the Following Questions

                                                                (10 marks)

       1.Write a program for Mouse Event Handling

import java.awt.*;

import java.awt.event.*;

import java.applet.*;

/*

<applet code="MouseEvents"width=300 height=100>

</applet>

*/

public class MouseEvents extends Applet

implements MouseListener,MouseMotionListener

{

String msg="";

int mouseX=0,mouseY=0;//coordinates of mouse

public void init()

{

addMouseListener(this);

addMouseMotionListener(this);

}

//Handle mouse clicked.

public void mouseClicked(MouseEvent me){

//save coordinates

mouseX=0;

mouseY=10;

msg="Mouse clicked.";

repaint();

}

//Handle mouse entered.

public void mouseEntered(MouseEvent me)

{

//save coordinates

mouseX=0;

mouseY=10;

msg="Mouse entered.";

repaint();

}

//Handle mouse exited.

public void mouseExited(MouseEvent me)

{

//save coordinates

mouseX=0;

mouseY=10;

msg="Mouse exited.";

repaint();

}

//Handle button pressed.

public void mousePressed(MouseEvent me)

{

//save coordinates

mouseX=me.getX();

mouseY=me.getY();

msg="Down";

repaint();

}

//Handle button released.

public void mouseReleased(MouseEvent me)

{

//save coordinates

mouseX=me.getX();

mouseY=me.getY();

msg="Up";

repaint();

}

//Handle mouse dragged.

public void mouseDragged(MouseEvent me)

{

//save coordinates

mouseX=me.getX();

mouseY=me.getY();

msg="*";

showStatus("Dragging mouse at"+mouseX+","+mouseY);

repaint();

}

//Handle mouse moved.

public void mouseMoved(MouseEvent me)

{

//show status

showStatus("Moving mouse at"+me.getX()+","+me.getY());

}

//Display msg in applet window at current X,Y location.

public void paint(Graphics g)

{

g.drawString(msg,mouseX,mouseY);

}

}

       2.Write a program for color changing event using  MouseAdapter class

import java.awt.*;

import java.awt.event.*;

import java.applet.*;

/*

<applet code="MouseEvents"width=300 height=100>

</applet>

*/

public class MouseEvents extends Applet

implements MouseListener,MouseMotionListener

{

String msg="";

int mouseX=0,mouseY=0;//coordinates of mouse

public void init()

{

addMouseListener(this);

addMouseMotionListener(this);

}

//Handle mouse clicked.

public void mouseClicked(MouseEvent me){

//save coordinates

mouseX=0;

mouseY=10;

msg="Mouse clicked.";

repaint();

}

//Handle mouse entered.

public void mouseEntered(MouseEvent me)

{

//save coordinates

mouseX=0;

mouseY=10;

msg="Mouse entered.";

repaint();

}

//Handle mouse exited.

public void mouseExited(MouseEvent me)

{

//save coordinates

mouseX=0;

mouseY=10;

msg="Mouse exited.";

repaint();

}

//Handle button pressed.

public void mousePressed(MouseEvent me)

{

//save coordinates

mouseX=me.getX();

mouseY=me.getY();

msg="Down";

repaint();

}

//Handle button released.

public void mouseReleased(MouseEvent me)

{

//save coordinates

mouseX=me.getX();

mouseY=me.getY();

msg="Up";

repaint();

}

//Handle mouse dragged.

public void mouseDragged(MouseEvent me)

{

//save coordinates

mouseX=me.getX();

mouseY=me.getY();

msg="*";

showStatus("Dragging mouse at"+mouseX+","+mouseY);

repaint();

}

//Handle mouse moved.

public void mouseMoved(MouseEvent me)

{

//show status

showStatus("Moving mouse at"+me.getX()+","+me.getY());

}

//Display msg in applet window at current X,Y location.

public void paint(Graphics g)

{

g.drawString(msg,mouseX,mouseY);

}

}

       3.Write a program to print Bar graph using Applet

File name: BarChart.java

import java.awt.*;

import java.applet.*;

public class BarChart extends Applet

{

int n=0;

String label[];

int value[];

public void init()

{

try

{

n=Integer.parseInt(getParameter("coloumn"));

label=new String[n];

value=new int[n];

label[0]=getParameter("label1");

label[1]=getParameter("label2");

label[2]=getParameter("label3");

label[3]=getParameter("label4");

value[0]=Integer.parseInt(getParameter("c1"));

value[1]=Integer.parseInt(getParameter("c2"));

value[2]=Integer.parseInt(getParameter("c3"));

value[3]=Integer.parseInt(getParameter("c4"));

}

catch(NumberFormatException e){}

}

public void paint(Graphics g)

{

for(int i=0;i<n;i++)

{

g.setColor(Color.red);

g.drawString(label[i],20,i*50+30);

g.fillRect(50,i*50+10,value[i],40);

}

}

}

/*<applet code="BarChart.class" width=300 Height=250>

<param name="coloumns" value="4">

<param name="c1" value="110">

<param name="c2" value="150">

<param name="c3" value="100">

<param name="c4" value="170">

<param name="label1" value="91">

<param name="label2" value="92">

<param name="label3" value="93">

<param name="label4" value="94">

</applet>

*/