设置Facebook登录 - 无法将回调解析为变量

Question

我正在学习本教程：https://developers.facebook.com/docs/android/login-with-facebook/#step1

以下是我的欢迎活动（主要活动）的代码：

package com.test.test;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.util.Log;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;


import com.facebook.*;
import com.facebook.android.Facebook;
import com.facebook.model.*;
import com.facebook.widget.FacebookDialog;
import com.facebook.Session;
import com.facebook.Request;
import com.facebook.SessionState;

public class Welcome extends FragmentActivity implements View.OnClickListener {
    private UiLifecycleHelper uiHelper;
private MainFragment mainFragment;
Button start_game;

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);



    Session.getActiveSession().onActivityResult(this, requestCode, resultCode, data);
    uiHelper.onActivityResult(requestCode, resultCode, data, new FacebookDialog.Callback() {
        @Override
        public void onError(FacebookDialog.PendingCall pendingCall, Exception error, Bundle data) {
            Log.e("Activity", String.format("Error: %s", error.toString()));
        }

        @Override
        public void onComplete(FacebookDialog.PendingCall pendingCall, Bundle data) {
            Log.i("Activity", "Success!");
        }
    });
}



@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    uiHelper.onSaveInstanceState(outState);
}



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
     if (savedInstanceState == null) {
            // Add the fragment on initial activity setup
            mainFragment = new MainFragment();
            getSupportFragmentManager()
            .beginTransaction()
            .add(android.R.id.content, mainFragment)
            .commit();
        } else {
            // Or set the fragment from restored state info
            mainFragment = (MainFragment) getSupportFragmentManager()
            .findFragmentById(android.R.id.content);
        }


    //fb
    uiHelper = new UiLifecycleHelper(this, callback);
    uiHelper.onCreate(savedInstanceState);




    setContentView(R.layout.welcome);
    start_game = (Button) findViewById(R.id.start_game);
    start_game.setOnClickListener(this);

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

        // callback when session changes state
        @Override
        public void call(Session session, SessionState state, Exception exception) {
            if (session.isOpened()) {
                //login succesful
                //like

            }
        }
      });

}

@Override
public void onClick(View arg0) {
    // TODO Auto-generated method stub
    switch (arg0.getId()) {
    case R.id.start_game:
        Intent openMain = new Intent("com.test.MainActivity");
        startActivity(openMain);
    case R.id.like_fb:

    }
}

这是我的MainFragment.java类的代码：

package de.test.test;

import java.util.Arrays;

import com.facebook.Session;
import com.facebook.SessionState;
import com.facebook.UiLifecycleHelper;
import com.facebook.widget.LoginButton;

import android.app.Activity;
import android.content.Intent;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class MainFragment extends Fragment {
    private static final String TAG = "MainFragment";
    private UiLifecycleHelper uiHelper;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    uiHelper = new UiLifecycleHelper(getActivity(), callback);
    uiHelper.onCreate(savedInstanceState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    View view = inflater.inflate(R.layout.welcome, container, false);
    LoginButton authButton = (LoginButton) view.findViewById(R.id.like_fb);
    authButton.setFragment(this);
    authButton.setReadPermissions(Arrays.asList("user_likes"));
    return view;
}

private void onSessionStateChange(Session session, SessionState state,
        Exception exception) {
    if (state.isOpened()) {
        Log.i(TAG, "Logged in...");
    } else if (state.isClosed()) {
        Log.i(TAG, "Logged out...");
    }
}

private Session.StatusCallback callback = new Session.StatusCallback() {
    @Override
    public void call(Session session, SessionState state,
            Exception exception) {
        onSessionStateChange(session, state, exception);
    }
};

@Override
public void onResume() {
    super.onResume();
    // For scenarios where the main activity is launched and user
    // session is not null, the session state change notification
    // may not be triggered. Trigger it if it's open/closed.
    Session session = Session.getActiveSession();
    if (session != null &&
           (session.isOpened() || session.isClosed()) ) {
        onSessionStateChange(session, session.getState(), null);
    }

    uiHelper.onResume();
}

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

@Override
public void onPause() {
    super.onPause();
    uiHelper.onPause();
}

@Override
public void onDestroy() {
    super.onDestroy();
    uiHelper.onDestroy();
}

@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    uiHelper.onSaveInstanceState(outState);
}

我不确定这是否正确。在这两个课程中，我都有这个＆＃34; uiHelper＆＃34;。此外，我在此行的欢迎活动中收到错误：

uiHelper = new UiLifecycleHelper(this, callback);

说＆＃34;回调无法解析为变量＆＃34;

谢谢！