Java Applet, Java Applet Hello World Examples

Java - Applet Hello World

This example introduces you with the Applet in Java. You will learn how to develop applet code and run in the browser.

Applet is a program provided by java which is designed for execution within the web browser. Applets are mostly used for a small internet and intranet applications because of small size and it's compatibility among almost all web browsers. Applets are also very secure. For example, Applets can be used to serve animated graphics on the web.

This example creates a simple applet that displays Hello World message.


import java.applet.Applet;

 
import java.awt.*;

 
import java.awt.event.*;

 

public class HelloWorldApplet extends Applet{

 
  public static void main(String[] args){


    Frame frame = new Frame("Roseindia.net");

    frame.setSize(400,200);


    Applet app = new HelloWorldApplet();


    frame.add(app);


    frame.setVisible(true);


    frame.addWindowListener(new WindowAdapter(){

       public void windowClosing(WindowEvent e){


        System.exit(0);

       }

     });

   }

   public void paint(Graphics g){


    g.drawString("Hello World!",200,100);

   }

 }

Compiling Applets:

javac HelloWorldApplet.java

Running Applet from console:

java HelloWorldApplet

Running Applet from Web browser:

Running applet in browser is very easy job, create an html file with the following code:

<html>
<head>
<title>A Simple Applet program</title>
</head>
<body>
<APPLET CODE="HelloWorldApplet.class" WIDTH=700 HEIGHT=500>
</APPLET>
</body>
</html>

The Applet tag in html is used to embed an applet in the web page.

<APPLET CODE="HelloWorldApplet.class" WIDTH=700 HEIGHT=500>

CODE tag is used to specify the name of Java applet class name. To test your applet open the html file in web browser. You browser should display applet. You can also try this applet online by clicking on the following link.

Current Comments

4 comments so far (post your own) View All Comments Latest 10 Comments:

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Posted by Rekha on Friday, 02.22.08 @ 11:58am | #49393

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Mahesh Palghadmal
Web Developer

Posted by Mahesh Palghadmal on Thursday, 01.17.08 @ 11:17am | #45409

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import java.awt.*;
import java.awt.event.*;
import java.applet.*;

public class CalculatorApplet extends Applet implements ActionListener
{
private Button keysArray[];
private Panel keyPad;
private TextField lcdField;
private double result;
private boolean first;
private boolean foundKey;
static boolean clearText;
private int prevOperator;

public void init()
{
lcdField = new TextField(20);
keyPad = new Panel ();
keysArray = new Button[17];
result = 0.0;
prevOperator = 0;
first = true;
clearText = true;

setLayout(new BorderLayout());

lcdField.setEditable(false);

for (int i = 0; i <=9; i++)
keysArray[i] = new Button(String.valueOf(i));
keysArray[10] = new Button("/");
keysArray[11] = new Button("*");
keysArray[12] = new Button("-");
keysArray[13] = new Button("+");
keysArray[14] = new Button("=");
keysArray[15] = new Button(".");
keysArray[16] = new Button("CLR");

keyPad.setLayout(new GridLayout (4,4));

for (int i = 7; i <=10; i++)
keyPad.add(keysArray[i]);

for (int i = 4; i <6; i++)
keyPad.add(keysArray[i]);

keyPad.add(keysArray[11]);

for (int i = 1; i <= 3;i++)
keyPad.add(keysArray[i]);

keyPad.add(keysArray[12]);

keyPad.add(keysArray[0]);

for (int i = 15; i >=13; i--)
keyPad.add(keysArray[i]);

add(lcdField, BorderLayout.NORTH);
add(keyPad, BorderLayout.CENTER);
add(keysArray[16], BorderLayout.EAST);

for(int i = 0; i < keysArray.length; i++)
keysArray[i].addActionListener(this);
}

public void actionPerformed(ActionEvent e)
{
foundKey = false;

for (int i = 0; i < keysArray.length && !foundKey; i++)
if(e.getSource() == keysArray[i])
{
foundKey = true;
switch(i)
{
case 0: case 1: case 2: case 3: case 4:
case 5: case 6: case 7: case 8: case 9:
case 15:
if (clearText)
{
lcdField.setText("");
clearText = false;
}
lcdField.setText(lcdField.getText() +
keysArray[i].getLabel());
break;

case 10:
case 11:
case 12:
case 13:
case 14:
clearText = true;
if (first)
{
if(lcdField.getText().length()==0)
result = 0.0;
else
result = Double.valueOf(lcdField.getText()).doubleValue();

first = false;
prevOperator = i;
}
else
{
switch(prevOperator)
{
case 10:
result /= Double.valueOf(lcdField.getText()).
doubleValue();
break;
case 11:
result *= Double.valueOf(lcdField.getText()).
doubleValue();
break;
case 12:
result -= Double.valueOf(lcdField.getText()).
doubleValue();
break;
case 13:
result += Double.valueOf(lcdField.getText()).
doubleValue();
break;
}
lcdField.setText(Double.toString(result));
if (i==14)
first = true;
else
prevOperator = i;
}
break;

case 16:
clearText = true;
first = true;
lcdField.setText("");
result = 0.0;
prevOperator = 0;
break;
}
}
}
}

whenever i try to run this or other applets
this msg is shown:

Exception in thread "main" java.lang.NoSuchMethodError: main

although there is no error found at the time of compilation.

Posted by ashok on Monday, 10.29.07 @ 16:15pm | #35063

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it is very good site to get knowledge. im very thanksfull to owner of this site and all support for me

Posted by sampat bhawar on Thursday, 06.14.07 @ 15:18pm | #19199

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