Hi i m learning java n
i have written the following program but it does not compile

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class Simple implements Filter
{
    public void doFilter(ServletRequest request, ServletResponse
response,    FilterChain chain)
   throws IOException, ServletException
 {

 }

 public void destroy()
 {

 }

 public void init(FilterConfig filterConfig)
 {

 }

}

when i come i get following errors
simple.java:4: class Simple is public, should be declared in a file
named Simple.java
public class Simple implements Filter
      ^
simple.java:2: package javax.servlet does not exist
import javax.servlet.*;
^
simple.java:3: package javax.servlet.http does not exist
import javax.servlet.http.*;
^
simple.java:4: cannot find symbol
symbol: class Filter
public class Simple implements Filter
                              ^
simple.java:6: cannot find symbol
symbol  : class ServletRequest
location: class Simple
    public void doFilter(ServletRequest request, ServletResponse
response,
                         ^
simple.java:6: cannot find symbol
symbol  : class ServletResponse
location: class Simple
    public void doFilter(ServletRequest request, ServletResponse
response,
                                                 ^
simple.java:7: cannot find symbol
symbol  : class FilterChain
location: class Simple
   FilterChain chain)
   ^
simple.java:8: cannot find symbol
symbol  : class ServletException
location: class Simple
   throws IOException, ServletException
                       ^
simple.java:18: cannot find symbol
symbol  : class FilterConfig
location: class Simple
 public void init(FilterConfig filterConfig)