Hello, and thanks for your reply.

I wrote alternatively as following :

|  package com.sforce.soap.client;
| 
|  import java.io.*;
|  import javax.xml.rpc.ServiceException;
|  import com.sforce.soap.enterprise.LoginResult;
|  import com.sforce.soap.enterprise.SessionHeader;
|  import com.sforce.soap.enterprise.SforceServiceLocator;
|  import com.sforce.soap.enterprise.SoapBindingStub;
|  import com.sforce.soap.enterprise.fault.ExceptionCode;
|  import com.sforce.soap.enterprise.fault.LoginFault;
|  import com.sforce.soap.schemas._class.MyHello.*;
| 
|  public class MyHelloClient {
| 
|      private SoapBindingStub binding;
|      static BufferedReader rdr = new BufferedReader(new InputStreamReader(System.in));
|     
|      public static void main(String[] args) throws ServiceException {
|          MyHelloClient mhc = new MyHelloClient();
|          mhc.run();
|      }
|     
|      private boolean login() throws ServiceException {
| 
|          String userName = getUserInput("Enter username: ");
|          String password = getUserInput("Enter password: ");
| 
|          binding = (SoapBindingStub) new SforceServiceLocator().getSoap();
|          binding.setTimeout(60000);
|          LoginResult loginResult;
|          try {
|              System.out.println("LOGGING IN NOW....");
|              loginResult = binding.login(userName, password);
|          }
|          catch (LoginFault ex) {
|              ExceptionCode exCode = ex.getExceptionCode();
|              if (exCode == ExceptionCode.FUNCTIONALITY_NOT_ENABLED ||
|                  exCode == ExceptionCode.INVALID_CLIENT ||
|                  exCode == ExceptionCode.INVALID_LOGIN ||
|                  exCode == ExceptionCode.LOGIN_DURING_RESTRICTED_DOMAIN ||
|                  exCode == ExceptionCode.LOGIN_DURING_RESTRICTED_TIME ||
|                  exCode == ExceptionCode.ORG_LOCKED ||
|                  exCode == ExceptionCode.PASSWORD_LOCKOUT ||
|                  exCode == ExceptionCode.SERVER_UNAVAILABLE ||
|                  exCode == ExceptionCode.TRIAL_EXPIRED ||
|                  exCode == ExceptionCode.UNSUPPORTED_CLIENT) {
|                  System.out.println("Please be sure that you have a valid username and password.");
|              } else {
|                  System.out.println(ex.getExceptionCode());
|                  System.out.println("An unexpected error has occurred." + ex.getMessage());
|              }
|              return false;
|          } catch (Exception ex) {
|              System.out.println("An unexpected error has occurred: " + ex.getMessage());
|              ex.printStackTrace();
|              return false;
|          }
| 
|          if (loginResult.isPasswordExpired()) {
|              System.out.println("An error has occurred. Your password has expired.");
|              return false;
|          }
| 
|          binding._setProperty(SoapBindingStub.ENDPOINT_ADDRESS_PROPERTY, loginResult.getServerUrl());
|          SessionHeader sh = new SessionHeader();
|          sh.setSessionId(loginResult.getSessionId());
|          binding.setHeader(new SforceServiceLocator().getServiceName().getNamespaceURI(),"SessionHeader", sh);
| 
|         
|          MyHelloBindingStub myHello = (MyHelloBindingStub) new MyHelloServiceLocator().getMyHello();
|          myHello._setProperty(SoapBindingStub.ENDPOINT_ADDRESS_PROPERTY, loginResult.getServerUrl());
|          myHello.setHeader(new MyHelloServiceLocator().getServiceName().getNamespaceURI(),"SessionHeader", sh);       
|          try {
|              System.out.println("Welcome : " + myHello.getHello("FoooBaar"));
|          }
|          catch(Exception e){
|              e.printStackTrace();
|          }
|         
|          return true;
|      }
| 
|      private void run() throws ServiceException {
|          if (login()) {
|              getUserInput("SUCESSFUL LOGIN! Hit the enter key to continue.");
|              System.out.println("SUCCESSFULLY COMPLETED.");
|          }
|      }
|     
|      String getUserInput(String prompt) {
|          System.out.print(prompt);
|          try {
|              return rdr.readLine();
|          }
|          catch (IOException ex) {
|              return null;
|          }
|      }
|     
|     
|  }

But the result is :

|  AxisFault
|   faultCode: {http://schemas.xmlsoap.org/soap/envelope/}Client
|   faultSubcode:
|   faultString: No operation available for request {http://soap.sforce.com/schemas/class/MyHello}getHello
|   faultActor:
|   faultNode:
|   faultDetail:
|      {http://xml.apache.org/axis/}stackTrace:No operation available for request {http://soap.sforce.com/schemas/class/MyHello}getHello

I can't understand what's wrong with my code.
If you understand, please help me.

Thanks.