public void actionPerformed(ActionEvent evt) {

if (evt.getSource()==users_b){
callServlet("Users");
}else if(evt.getSource()==item_b) {
callServlet("Item");
}

}
private void callServlet(String command) {

try {
URL phoneServlet = new URL(getDocumentBase(), "servlet/MyServlet");
ServletMessage msg = new ServletMessage(phoneServlet);
Properties args = new Properties();

if (command != null && command.length() > 0) {
args.put("name", command);
}
InputStream result = msg.sendMessage(args, ServletMessage.POST);
ObjectInputStream in = new ObjectInputStream(result);
list.removeAll();
if(command.equals("Users")){
UsersEntity users[]=(UsersEntity [])in.readObject();
display(users);
}else if(command.equals("Item")){
ItemEntity item[]=(ItemEntity [])in.readObject();
display(item);
}
} catch (IOException exc) {
showStatus("Cannot read Data: 1" + exc.toString());
}catch(Exception ee){
showStatus("Cannot read Data: 2" + ee.toString());
}

}

public void display(Object o[]){

if(o instanceof UsersEntity[]){
UsersEntity users[]=(UsersEntity[])o;
for (int i=0;i<users.length ;i++ )
{
list.add(users[i].user_id+" "+users[i].getUser_name()+" "+users[i].getUser_address());
}
}else if (o instanceof ItemEntity[]){
ItemEntity item[]=(ItemEntity[])o;
for (int i=0;i<item.length ;i++ )
{
list.add(item[i].getItem_name()+" "+item[i].getItem_price());
}
}

}

import java.util.*;
import java.net.*;
import java.io.*;

public class ServletMessage {

public static int GET = 0;
public static int POST = 1;
private URL servlet;

public ServletMessage(URL servlet) {

this.servlet = servlet;
System.out.println(servlet.toString());

}
public InputStream sendMessage(Properties args) throws IOException {

return sendMessage(args, POST);

}
public InputStream sendMessage(Properties args, int method)
throws IOException {

if (method == GET) {
URL url = new URL(servlet.toExternalForm() + "?" +
toEncodedString(args));
return url.openStream();

} else {
URLConnection conn = servlet.openConnection();
conn.setDoOutput(true);
conn.setUseCaches(false);

// POST the request data (html form encoded)
PrintStream out = new PrintStream(conn.getOutputStream());
if (args != null && args.size() > 0) {
System.out.println("POST "+toEncodedString(args));
out.print(toEncodedString(args));
}
out.close(); // ESSENTIAL for this to work!

// Read the POST response data
return conn.getInputStream();
}

}
public String toEncodedString(Properties args) {

StringBuffer sb = new StringBuffer();
if (args != null) {
String sep = "";
Enumeration names = args.propertyNames();
while (names.hasMoreElements()) {
String name = (String)names.nextElement();
System.out.println(name);
sb.append(sep + URLEncoder.encode(name) + "=" +
URLEncoder.encode(args.getProperty(name)));
System.out.println(sep + URLEncoder.encode(name) + "=" +
URLEncoder.encode(args.getProperty(name)));
sep = "&";
}
}
System.out.println(sb.toString());
return sb.toString();

}

}