Facebook Integration Error - NullPointerException

Question

im trying to integrate Facebook SDK with my application, but i can't fix the NullPointer Exception.

Im following the tutorial: http://www.portalandroid.org/comunidade/viewtopic.php?f=7&t=185&view=previous

My Code:

    package com.example.jeneves;

import java.util.Arrays;

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

import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.TextView;

/**
 * A placeholder fragment containing a simple view.
 */

public  class Login extends Fragment {
Button btnEnviar;
EditText edtPost;
TextView txtName;


ImageView imgAvatar;
    private static final String TAG = "Login";
    private UiLifecycleHelper uiHelper;
    private Session session;


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_login, container, false);

        imgAvatar  = (ImageView) view.findViewById(R.id.imgAvatar);
        txtName = (TextView) view.findViewById(R.id.textUserName);
        edtPost = (EditText) view.findViewById(R.id.postMsg);
        btnEnviar = (Button) view.findViewById(R.id.btnEnviar);

        LoginButton authButton = (LoginButton) view.findViewById(R.id.login_button);
        authButton.setFragment(this);
        authButton.setReadPermissions(Arrays.asList("user_likes", "user_status"));

        return view;
    }

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


    private Session.StatusCallback callback = new Session.StatusCallback() {
        @Override
        public void call(Session session, SessionState state, Exception exception)  {
           if (state.isOpened()) {
              Log.i(TAG, "Logged in...");
           } else if (state.isClosed()) {
              Log.i(TAG, "Logged out...");
           }
        }
     };

     @Override
     public void onResume() {
        super.onResume();
        if (session.isOpened()) {
           Log.i(TAG, "Logged in...");
        } else if (session.isClosed()) {
           Log.i(TAG, "Logged out...");
        }
        uiHelper.onResume();
     }

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

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


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

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


}

My Log Cat Error:

    04-17 18:07:58.854: D/AndroidRuntime(14047): Shutting down VM
04-17 18:07:58.854: W/dalvikvm(14047): threadid=1: thread exiting with uncaught exception (group=0x41f87ba8)
04-17 18:07:58.864: E/AndroidRuntime(14047): FATAL EXCEPTION: main
04-17 18:07:58.864: E/AndroidRuntime(14047): Process: com.example.jeneves, PID: 14047
04-17 18:07:58.864: E/AndroidRuntime(14047): java.lang.RuntimeException: Unable to resume activity {com.example.jeneves/com.example.jeneves.MainActivity}: java.lang.NullPointerException
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2788)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2817)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2250)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.app.ActivityThread.access$800(ActivityThread.java:135)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.os.Handler.dispatchMessage(Handler.java:102)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.os.Looper.loop(Looper.java:136)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.app.ActivityThread.main(ActivityThread.java:5017)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at java.lang.reflect.Method.invokeNative(Native Method)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at java.lang.reflect.Method.invoke(Method.java:515)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at dalvik.system.NativeStart.main(Native Method)
04-17 18:07:58.864: E/AndroidRuntime(14047): Caused by: java.lang.NullPointerException
04-17 18:07:58.864: E/AndroidRuntime(14047):    at com.example.jeneves.Login.onResume(Login.java:73)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.support.v4.app.Fragment.performResume(Fragment.java:1543)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:963)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1086)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.support.v4.app.FragmentManagerImpl.dispatchResume(FragmentManager.java:1894)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.support.v4.app.FragmentActivity.onResumeFragments(FragmentActivity.java:466)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.support.v4.app.FragmentActivity.onPostResume(FragmentActivity.java:455)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.support.v7.app.ActionBarActivity.onPostResume(ActionBarActivity.java:115)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.app.Activity.performResume(Activity.java:5323)
04-17 18:07:58.864: E/AndroidRuntime(14047):    at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2778)
04-17 18:07:58.864: E/AndroidRuntime(14047):    ... 12 more

Answer 1

session is not initialized. You should initialize it before onResume().

Answer 2

Seems like the session var in onResume() is the culprit.

Answer 3

Try this:

public void onSaveInstanceState(Bundle savedInstanceState) {

    if (savedInstanceState != null) 
    {
      super.onSaveInstanceState(savedInstanceState);
    }
    uiHelper.onSaveInstanceState(savedInstanceState);
 }