无法验证登录

我正在编写一个程序来验证无法正常登录。不会发生任何错误，但不会为不正确的登录生成吐司文本。我认为条件状态出问题了。如果登录错误，它将响应日志中显示的“ null”。

但是我找不到问题所在，有人可以帮忙吗？

        HttpClient client = new DefaultHttpClient();

        try {
            ArrayList<NameValuePair> parameters = new ArrayList<NameValuePair>();
            parameters.add(new BasicNameValuePair("login", loginText));
            parameters.add(new BasicNameValuePair("password", pwText));

            String url = controller.bniRootUrl+
                    controller.folderUser+
                    controller.fileLogin+
                    "?";

            url += URLEncodedUtils.format(parameters, "utf-8");

            HttpGet get = new HttpGet(url);
            HttpResponse response = client.execute(get);

            loginResponse = EntityUtils.toString(response.getEntity());

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        Log.d(TAG, "response: "+loginResponse);
        if (loginResponse == null || loginResponse == "null" || loginResponse.isEmpty()){
            Toast.makeText(Login.this, "invalid login", Toast.LENGTH_SHORT).show();
        }