Data Represent in the form User-defined Object (Bean)

public class Student {
private String studentNo;
private String studentName;
private float studentFee;

public float getStudentFee() {
return studentFee;
}
public void setStudentFee(float studentFee) {
this.studentFee = studentFee;
}
public String getStudentNo() {
return studentNo;
}
public void setStudentNo(String studentNo) {
this.studentNo = studentNo;
}
public String getStudentName() {
return studentName;
}
public void setStudentName(String studentName) {
this.studentName = studentName;
}

}

Servlets- Inserting a Employee Details by using the PreparedStatement()

/*Before Executing dis program you should create Employee Table in the database And "emp.html" with eno,ename,salary field......*/

package com.edu.servlets;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.sql.*;
public class EmployeeServlet extends HttpServlet{
Connection con;
PreparedStatement ps;
public void init(ServletConfig config) throws ServletException{
String driver=config.getInitParameter("driver");
String cs=config.getInitParameter("url");
String usr=config.getInitParameter("user");
String pwd=config.getInitParameter("pwd");
 try
  {
  Class.forName(driver);
  con=DriverManager.getConnection(cs,usr,pwd);
  ps=con.prepareStatement("Insert into employee values(?,?,?)");
  }
 catch(ClassNotFoundException e){
 e.printStackTrace();
 }
 catch(SQLException e)
 {
 e.printStackTrace();
 }
}//init()
public void destroy(){
try
  {
   if(ps!=null)
     ps.close();
   if(con!=null)
     con.close();
  }
catch(SQLException e)
  {
  e.printStackTrace();
  }
  }
public void doPost(HttpServletRequest request,HttpServletResponse response)
throws ServletException,IOException{
 String a=request.getParameter("empno");
 String name=request.getParameter("name");
 String c=request.getParameter("salary");
 int eno=Integer.parseInt(a);
 float salary=Float.parseFloat(c);
 try{
 ps.setInt(1,eno);
 ps.setString(2,name);
 ps.setFloat(3,salary);
 ps.executeUpdate();
 }catch(SQLException e)
 {
  e.printStackTrace();
 }
 response.sendRedirect("emp.html");
 }//doPost()
}//EmployyeeServlet class

HelloWorld Application By Using Servlets.......

package com.edu.servlets;
import javax.servlet.*;
import java.io.*;
public class HelloWorldServlet extends Servlet
throws ServletException,IOException{
public HelloWorldServlet(){
System.out.println("Construstor");
}

public  init(ServletConfig config){
System.out.println("init() initialised");
}
public destroy(){
System.out.println("destroy() initialised");
}
public service(ServletRequest request,ServletResponse response){
//request.getParameter("t");
//response.getParameter(
System.out.println("Hello World");
}
ServletConfig(getServletConfig config)
{
return "some thing";
}
ServletInfo(getServletInfo info)
{
return null;
}
}

Multithreading by using sleep() method .Numbers are printing line by line after 5 seconds

public class Threads{
  public static void main(String[] args){
    Thread th = new Thread();    System.out.println("Numbers are printing line by line after 5 seconds : ");
    try{      for(int i = 1;i <= 10;i++)
      {
        System.out.println(i);
        th.sleep(5000);
      }    }    catch(InterruptedException e){
      System.out.println("Thread interrupted!");      e.printStackTrace();
    }
  }
}