在Android中的android facebook集成中获取异常

Question

我已经为facebook集成制作了一个演示Android应用程序，我已经按照以下教程一步一步地进行，Facebook connect tutorial我成功获得了access_token，但之后我在应用程序中得到了一个nullpointer异常

我的代码

private static String APP_ID = "1464688850452016"; // Replace with your App
    // ID

    // Instance of Facebook Class
    private Facebook facebook = new Facebook(APP_ID);
    private AsyncFacebookRunner mAsyncRunner;
    String FILENAME = "AndroidSSO_data";
    private SharedPreferences mPrefs;



    Button btn_fb;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(R.layout.activity_login);
        mAsyncRunner = new AsyncFacebookRunner(facebook);



        init();

        btn_login.setOnClickListener(this);

    }

    @SuppressWarnings("deprecation")
    void init() {
        facebook = new Facebook(APP_ID);
        new AsyncFacebookRunner(facebook);

        btn_fb = (Button) findViewById(R.id.btn_fb);
        btn_fb.setOnClickListener(this);

    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
                case R.id.btn_fb:
            Log.d("Image Button", "button Clicked");
            loginToFacebook();
            break;
        }
    }


    // Login From Facebook...!!!
    // Checking facebook session..!!!
    public void loginToFacebook() {
        facebook.authorize(this, new String[] { "email", "publish_stream" },
                new DialogListener() {

                    @Override
                    public void onCancel() {
                        // Function to handle cancel event
                    }

                    @Override
                    public void onComplete(Bundle values) {
                        // Function to handle complete event
                        // Edit Preferences and update facebook acess_token
                        SharedPreferences.Editor editor = mPrefs.edit();
                        editor.putString("access_token",
                                facebook.getAccessToken());
                        editor.putLong("access_expires",
                                facebook.getAccessExpires());
                        editor.commit();

                        // Making Login button invisible

                    }

                    @Override
                    public void onError(DialogError error) {
                        // Function to handle error

                    }

                    @Override
                    public void onFacebookError(FacebookError fberror) {
                        // Function to handle Facebook errors

                    }

                });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        // TODO Auto-generated method stub
        super.onActivityResult(requestCode, resultCode, data);
        facebook.authorizeCallback(requestCode, resultCode, data);
    }

}

Logcat跟踪

08-29 11:57:01.292: E/AndroidRuntime(10924): FATAL EXCEPTION: main
08-29 11:57:01.292: E/AndroidRuntime(10924): Process: com.eps.fortalented, PID: 10924
08-29 11:57:01.292: E/AndroidRuntime(10924): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=32665, result=-1, data=Intent { (has extras) }} to activity {com.eps.fortalented/com.eps.fortalented.ui.LoginActivity}: java.lang.NullPointerException
08-29 11:57:01.292: E/AndroidRuntime(10924):    at android.app.ActivityThread.deliverResults(ActivityThread.java:3700)
08-29 11:57:01.292: E/AndroidRuntime(10924):    at android.app.ActivityThread.handleSendResult(ActivityThread.java:3743)
08-29 11:57:01.292: E/AndroidRuntime(10924):    at android.app.ActivityThread.access$1400(ActivityThread.java:172)
08-29 11:57:01.292: E/AndroidRuntime(10924):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1356)
08-29 11:57:01.292: E/AndroidRuntime(10924):    at android.os.Handler.dispatchMessage(Handler.java:102)
08-29 11:57:01.292: E/AndroidRuntime(10924):    at android.os.Looper.loop(Looper.java:146)
08-29 11:57:01.292: E/AndroidRuntime(10924):    at android.app.ActivityThread.main(ActivityThread.java:5653)
08-29 11:57:01.292: E/AndroidRuntime(10924):    at java.lang.reflect.Method.invokeNative(Native Method)
08-29 11:57:01.292: E/AndroidRuntime(10924):    at java.lang.reflect.Method.invoke(Method.java:515)
08-29 11:57:01.292: E/AndroidRuntime(10924):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
08-29 11:57:01.292: E/AndroidRuntime(10924):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
08-29 11:57:01.292: E/AndroidRuntime(10924):    at dalvik.system.NativeStart.main(Native Method)
08-29 11:57:01.292: E/AndroidRuntime(10924): Caused by: java.lang.NullPointerException
08-29 11:57:01.292: E/AndroidRuntime(10924):    at com.eps.fortalented.ui.LoginActivity$4.onComplete(LoginActivity.java:435)
08-29 11:57:01.292: E/AndroidRuntime(10924):    at com.facebook.android.Facebook.authorizeCallback(Facebook.java:399)
08-29 11:57:01.292: E/AndroidRuntime(10924):    at com.eps.fortalented.ui.LoginActivity.onActivityResult(LoginActivity.java:465)
08-29 11:57:01.292: E/AndroidRuntime(10924):    at android.app.Activity.dispatchActivityResult(Activity.java:5734)
08-29 11:57:01.292: E/AndroidRuntime(10924):    at android.app.ActivityThread.deliverResults(ActivityThread.java:3696)