Facebook Sdk session.isOpened（）总是返回false？

Question

我正在使用Facebook sdk，我正在关注this link

中的“使用Facebook登录创建一个新的Android项目”部分

我的活动代码在这里：

    import android.os.Bundle;
    import android.app.Activity;
    import android.content.Intent;
    import android.widget.TextView;
    import com.facebook.*;
    import com.facebook.model.*;

    public class MainActivity extends Activity {

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);

            // start Facebook Login
            Session.openActiveSession(this, true, new Session.StatusCallback() {

              // callback when session changes state
              @SuppressWarnings("deprecation")
            @Override
              public void call(Session session, SessionState state, Exception exception) {


  **if (session.isOpened()) {**


                  // make request to the /me API
                  Request.executeMeRequestAsync(session, new Request.GraphUserCallback() {

                    // callback after Graph API response with user object
                    @Override
                    public void onCompleted(GraphUser user, Response response) {
                      if (user != null) {
                        TextView welcome = (TextView) findViewById(R.id.welcome);
                        welcome.setText("Hello " + user.getName() + "!");
                      }
                    }
                  });
                }
              }
            });
          }

          @Override
          public void onActivityResult(int requestCode, int resultCode, Intent data) {
              super.onActivityResult(requestCode, resultCode, data);
              Session.getActiveSession().onActivityResult(this, requestCode, resultCode, data);
          }



    }

session.isOpened（）总是返回false.I调试也是sdk但它对我不起作用。任何人都可以帮帮我吗？