Android应用程序不会显示登录页面找不到用户

Question

我正在设计一个Android应用程序，但问题是它没有显示用户找不到登录页面，或者没有显示密码是否错误我使用此代码。

    String ip = sharedpreferences.getString("ip", "");
        HttpPost httppost = new       HttpPost("http://"+ip+":8080/HibernateWebApp/register");
        List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(1);
        nameValuePairs.add(new BasicNameValuePair("signInOrUp", "1"));
        nameValuePairs.add(new BasicNameValuePair("userName", user
                .getText().toString()));
        nameValuePairs.add(new BasicNameValuePair("password1", pass
                .getText().toString()));

        try {
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

            try {
                HttpResponse response = httpclient.execute(httppost);
                String jsonString = inputStreamToString(
                        response.getEntity().getContent()).toString();
                if (jsonString.equalsIgnoreCase("f")) {
                    Intent i = new Intent(getBaseContext(),
                            ScanActivity.class);
                    startActivity(i);
                    LoginActivity.this.finish();
                } else {
                    Toast.makeText(LoginActivity.this,
                            "User not Found", Toast.LENGTH_LONG)
                            .show();
                }

这是错误密码的一部分

    if (jsonString.equalsIgnoreCase("f")) {
                    Intent i = new Intent(getBaseContext(),
                            ScanActivity.class);
                    startActivity(i);
                    LoginActivity.this.finish();
                } else {
                    Toast.makeText(LoginActivity.this,
                            "User not Found", Toast.LENGTH_LONG)
                            .show();
                }