How can I fix this compilation error in my program?
<pre><code>import javax.servlet.ServletException;
import javax.servlet.HttpServlet;
import javax.servlet.HttpServletRequest;
import javax.servlet.HttpServletResponse;
public class UrlRewrite extends HttpServlet
{
public void doGet(HttpServletRequest request,HttpServletResponse response)
throws ServletException,java.io.IOException
{
response.setContentType("text/html");
java.io.printwriter out=response.getWriter();
String contextPath=request.getContentPath();
String encodeURL=response.encodeURL(contextPath + "/run3");
out.println("&lt;html&gt;");
out.println("&lt;head&gt;");
out.println("&lt;title&gt;URL Rewrite&lt;/title&gt;");
out.println("&lt;/head&gt;");
out.println("&lt;body&gt;");
out.println("&lt;h1&gt;This page will use URL Rewriting if necessary&lt;/h2&gt;");
out.println("Go to the default jsp page&lt;a href=\"" + encodeURL + "\"&gt;here&lt;/a&gt;.");
out.println("&lt;/body&gt;");
out.println("&lt;/html&gt;");
}
public void doPost(HttpServletRequest request,HttpServletResponse response)
throws ServletException,java.io.IOException
{
doGet(request,response);
}
}
</code></pre>

<p>in program i have 9 errors like:</p>

<pre><code>1. UrlRewrite.java:2:connot find symbol
  symbol:class HttpServlet
  location: package javax.servlet
  import javax.servlet.HttpServlet;
                      ^
2. UrlRewrite.java:3:connot find symbol
  symbol:class HttpServletRequest
  location: package javax.servlet
  import javax.servlet.HttpServletRequest;
                      ^
3. UrlRewrite.java:4:connot find symbol
  symbol:class HttpServletResponse
  location: package javax.servlet
  import javax.servlet.HttpServletResponse;
                      ^
4. UrlRewrite.java:5:connot find symbol
  symbol:class HttpServlet
  public class UrlRewrite extends HttpServlet
                                  ^
5. UrlRewrite.java:7:connot find symbol
  symbol:class HttpServletRequest
  location:class UrlRewrite  
  public void doGet(HttpServletRequest request,HttpServletResponse response)
                    ^
6. UrlRewrite.java:7:connot find symbol
  symbol:class HttpServletResponse
  location:class UrlRewrite  
  public void doGet(HttpServletRequest request,HttpServletResponse response)
                    ^
7. UrlRewrite.java:24:connot find symbol
  symbol:class HttpServletReponse
  location:class UrlRewrite  
  public void doGet(HttpServletRequest request,HttpServletResponse response)
                    ^
8. UrlRewrite.java:24:connot find symbol
  symbol:class HttpServletRequest
  location:class UrlRewrite  
  public void doGet(HttpServletRequest request,HttpServletResponse response)
                    ^
9. UrlRewrite.java:11:connot find symbol
  symbol:class printWriterHttpServletRequest
  location:package java.io
  java.io.printwriter out=response.getWriter();  
         ^
</code></pre>
