Android facebook applicationId cannot be null

I've been following the following tutorial to integrate my app with Facebook. Facebook tutorial

I've followed everything on the tutorial, but I've been getting applicationId cannot be null in two cases, and it's really frustrating.

My FacebookActivity onCreate has the following, which is exactly the same as the tutorial:

public void onCreate(Bundle savedInstanceState) 
{ 
    super.onCreate(savedInstanceState);
    uiHelper = new UiLifecycleHelper(this, callback);
    uiHelper.onCreate(savedInstanceState);
    setContentView(R.layout.main_fb);

    FragmentManager fm = getSupportFragmentManager();
    fragments[SPLASH] = fm.findFragmentById(R.id.splashFragment);
    fragments[SELECTION] = fm.findFragmentById(R.id.selectionFragment);

    FragmentTransaction transaction = fm.beginTransaction();
    for(int i = 0; i < fragments.length; i++) 
    {
        transaction.hide(fragments[i]);
    }
    transaction.commit();
}

However when I try to display the activity I get applicationId cannot be null, and the line LogCat points me to is: uiHelper.onCreate(savedInstanceState);

So then I tried commenting out that line, and the activity is displayed. However now when I click on the LoginButton, I get the same error but this time is points me to the applicationId field in the LoginButton class from facebook.

I already have the Id in my string values and my manifest like this:

<meta-data android:name="com.facebook.sdk.ApplicationId" android:value="@string/APP_ID"/>

I tried getting the Id using code, but nothing changed.

What exactly is causing all this?

TL;DR: you have to write your application's ID in your strings.xml and then reference (i.e. @strings/fb_app_id), because if you put it directly (as value) into AndroidManifest.xml it won't work.

you must define your applicationId in the AndroidManifest.xml like this:

<meta-data android:name="com.facebook.sdk.ApplicationId" android:value="@string/app_id"/>

under <application android:label="@string/app_name".... tag

where app_id is a string within your strings.xml.

sample:

 <application android:label="@string/app_name"
                 android:icon="@drawable/icon"
                 android:theme="@android:style/Theme.NoTitleBar"
            >
        <activity android:name=".HelloFacebookSampleActivity"
                  android:label="@string/app_name"
                  android:windowSoftInputMode="adjustResize">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        <activity android:name="com.facebook.LoginActivity"
                  android:theme="@android:style/Theme.Translucent.NoTitleBar"
                  android:label="@string/app_name" />
        <meta-data android:name="com.facebook.sdk.ApplicationId" android:value="@string/app_id"/>
    </application>

** please note <meta-data android:name="com.facebook.sdk.ApplicationId" android:value="@string/app_id"/> is within <application> tag

-- and in strings.xml

<string name="app_id">1389xxxxxxxx</string>

Since today the answer is not quite correct. If someone didn't use this: AppEventsLogger.activateApp(this);

Since last update you must do it or your app will crashed. And you also should pass Application here not Context

https://developers.facebook.com/docs/android/getting-started

// Add this to the header of your file:
import com.facebook.FacebookSdk;

public class MyApplication extends Application {
    // Updated your class body:
    @Override
    public void onCreate() {
        super.onCreate();
        // Initialize the SDK before executing any other operations,
        FacebookSdk.sdkInitialize(getApplicationContext());
        AppEventsLogger.activateApp(this);
    }
}

The problem is that the id is being converted to integer: https://code.google.com/p/android/issues/detail?id=78839

In my case the facebook_app_id was being set from the build.gradle file per flavor.

The solution was to wrap the id with ":

flavor.resValue "string", "facebook_app_id", "\"1111111111111\""

or if you would rather avoid escaping:

flavor.resValue "string", "facebook_app_id", '"1111111111111"'