Code:

import java.rmi.RemoteException;
import javax.xml.rpc.Stub;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
import javax.microedition.midlet.MIDletStateChangeException;
import com.game.web.ServiceSoap_Stub;

public class HelloWorld3 extends MIDlet implements CommandListener {
    //private String webServiceURL = "http://localhost/javaGame/Service.asmx";
    private Command exitCommand; 
    
    private String userDataString = "";
    private Display display;
    private TextField userName,password;
    public Form form;
    private Command login,cancel;    
    
    public HelloWorld3() {
        exitCommand = new Command("Exit", Command.EXIT, 0);
        form = new Form("Sign in");
        userName = new TextField("LoginID:", "", 30, TextField.ANY);
        password = new TextField("Password:", "", 30, TextField.PASSWORD);
        cancel = new Command("Cancel", Command.CANCEL, 2);
        login = new Command("Login", Command.OK, 2);
    }

    public void startApp() {        
        display = Display.getDisplay(this);        
        form.append(userName);
        form.append(password);
        form.addCommand(cancel);
        form.addCommand(login);
        form.setCommandListener(this);
        display.setCurrent(form);
        
    }
    
  
    public void pauseApp() {
    }

    public void destroyApp(boolean unconditional) {
        notifyDestroyed();
    }

    public void commandAction(Command c, Displayable s) {
        String label = c.getLabel();
        if(label.equals("Cancel")) {
          destroyApp(true);
        } else if(label.equals("Login")) {
            ConnectionLogic cn = new ConnectionLogic(userName.getString(), password.getString());
            Thread th = new Thread(cn);
            th.start();
            if (cn.GetJmbg() == "")
            {
                tryAgain();               
            }
            else
            {
                showMsg();
            }
            
            
        }        
    }
   
      public void showMsg() {
        Alert success = new Alert("Your Login Process is completed!");        
        userName.setString("");
        password.setString("");
        display.setCurrent(success, form);    
      }

      public void tryAgain() {
        Alert error = new Alert("Please try again");
        error.setTimeout(900);        
        userName.setString("");
        password.setString("");
        display.setCurrent(error, form);
      }
}
class ConnectionLogic implements Runnable
{
    private String username;
    private String password;
    
    private String jmbg;
    
    public String GetJmbg()
    {
            return jmbg;
        
    }
    
    private String webServiceURL = "http://localhost/javaGame/Service.asmx";
    public ConnectionLogic()
    {        
    }
    public ConnectionLogic(String uname, String pass)
    {
        this.username = uname;
        this.password = pass;        
    }
    public void run() 
    {
        try{
            ServiceSoap_Stub service = new ServiceSoap_Stub();
            service._setProperty(Stub.ENDPOINT_ADDRESS_PROPERTY, webServiceURL);
            service._setProperty(Stub.SESSION_MAINTAIN_PROPERTY, Boolean.FALSE);
            jmbg = service.loginUser(username, password);        
            
            }
            catch (RemoteException e){
                
            }   
        
    }
    
}