Implement a program to generate and verify CAPTCHA image.

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

     class no
{

     public String generateCaptcha() {
      Random random = new Random();
      int length = 5;
      StringBuffer captchaStringBuffer = new StringBuffer();
      for (int i = 0; i < length; i++) {
       int captchaNumber = Math.abs(random.nextInt()) % 60;
       int charNumber = 0;
       if (captchaNumber < 26) {
        charNumber = 65 + captchaNumber;
       }
       else if (captchaNumber < 52){
        charNumber = 97 + (captchaNumber - 26);
       }
       else {
        charNumber = 48 + (captchaNumber - 52);
       }
       captchaStringBuffer.append((char)charNumber);
      }
     
      return captchaStringBuffer.toString();
     }  
    }
public class captcha2 extends Applet implements ActionListener
{
String str,s2,cmd,str2;
TextField t;
Button b,b2,b3;
Label l2,l,l3,l4;
public void init()
{
no noobj = new no();
str = noobj.generateCaptcha();
l=new Label(str);
add(l);
s2=str.toLowerCase();
l4=new Label(s2);
l3=new Label("Enter in small:");
add(l3);
t=new TextField(5);
add(t);
l2= new Label("              ");
add(l2);
b=new Button("Submit");
add(b);
b2=new Button("Refresh");
add(b2);
b.addActionListener(this);
b2.addActionListener(this);
}
public void actionPerformed(ActionEvent ae)
{
cmd=ae.getActionCommand();
if(cmd.equals("Submit"))
{
if(t.getText().equals(s2))
{
l2.setText("Success");
}
else
{
l2.setText("Failure");
}
}
else if(cmd.equals("Refresh"))
{
no noobj2 = new no();
     str2 = noobj2.generateCaptcha();
l.setText(str2);
t.setText("");
l2.setText("");
}

}}
/*<applet code="captcha2.class" height=300 width=700></applet>*/

****************OUTPUT*************************
[soet@localhost ~]$ javac captcha2.java
[soet@localhost ~]$ appletviewer captcha2.java