UnAuthorize XAuth in Android

[maidinhthaison]

I have used the OAuth 1.0a and result is very successful when I get successful the access token, and then I am developing an application on Android use XAuth ,with experience in OAuth 1.0a I have done the XAuth but always get 401 UnAuthorize status code.I cannot understand I thik eevrything is correct.Please explain me.I am very grateful.Thank you very much.
Here is my code:

boolean flag=false;
try{
String oauth_nonce=getOAuthNonce();
String oauth_timestamp=getTimestamp();
String signatureBaseString =
“POST”

• “&”
• URLEncoder.encode(“https://api.twitter.com/oauth/access_token”)
• “&”
• URLEncoder.encode(“oauth_consumer_key=Cp3jukLlGarRUyk4DReoHg”)
• URLEncoder.encode("&" + “oauth_nonce=” + oauth_nonce)
• URLEncoder.encode("&" + “oauth_signature_method=” + “HMAC-SHA1”)
• URLEncoder.encode("&" + “oauth_timestamp=” + oauth_timestamp)
• URLEncoder.encode("&" + “oauth_version=” + “1.0”)
• URLEncoder.encode("&" + “x_auth_username=” + URLEncoder.encode(“XXXX”))
• URLEncoder.encode("&" + “x_auth_password=” + URLEncoder.encode(“XXXXX”))
• URLEncoder.encode("&" + “x_auth_mode=” + URLEncoder.encode(“client_auth”));
  String oauth_signature=getSignatureToken(signatureBaseString, “HmacSHA1”,
  “cB2kzOq64ZOO0dmqH3HhcRdMsC2xPr3a99FJOIC4j8”+"&");
  String headerValue = “OAuth " +
  “oauth_nonce=””+oauth_nonce+""," +
  “oauth_signature_method=”"+“HMAC-SHA1”+""," +
  “oauth_timestamp=”"+oauth_timestamp+""," +
  “oauth_consumer_key=”"+“Cp3jukLlGarRUyk4DReoHg”+""," +
  “oauth_signature=”"+URLEncoder.encode(oauth_signature,“UTF-8”)+""," +
  “oauth_version=”"+“1.0”+""";
  HttpPost httppost = new HttpPost(“https://api.twitter.com/oauth/access_token”
  +"?x_auth_username="+URLEncoder.encode(“XXXX”)
  +"&x_auth_password="+URLEncoder.encode(“XXXX”)
  +"&x_auth_mode="+URLEncoder.encode(“client_auth”)

);

httppost.setHeader(“Host”,“api.twitter.com”);
httppost.setHeader(“Content-Type”,“application/x-www-form-urlencoded”);
httppost.setHeader(“Authorization”,headerValue);

// Execute HTTP Post Request
HttpClient httpclient = new DefaultHttpClient();
HttpResponse response = httpclient.execute(httppost);
StatusLine statusLine = response.getStatusLine();
if (statusLine.getStatusCode() == HttpStatus.SC_OK) {
HttpEntity entity = response.getEntity();
if (entity != null) {
jString=EntityUtils.toString(entity);
flag=true;
}
}else{
flag=false;
}
Log.e(“statusLine”, statusLine.getReasonPhrase());
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
Log.e(“e”, e.getMessage());
} catch (IOException e1) {
// TODO Auto-generated catch block
Log.e(“e1”, e1.getMessage());
}
return flag;