Facebook Sdk Has Not Been Initialized FacebookSdk.sdkInitialize()

Hey I know this was asked before, but none of the solutions seem to help. I'm using first time Facebook SDK in my application.

What I've tried:

I had tried most of the things found on Internet but did not get anything regarding this.

Here is my MainActivity.java:

 public class MainActivity extends Activity {

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

Here is My Activitymain.xml:

 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:facebook="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

 <com.facebook.login.widget.LoginButton
    android:id="@+id/connectWithFbButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerInParent="true"
    android:layout_gravity="center_horizontal"
    android:text="  connect_with_facebook" /> 
</LinearLayout>

see my Logcat:

 05-13 16:30:39.332: E/AndroidRuntime(10264): Caused by: The SDK has not been initialized, make sure to call FacebookSdk.sdkInitialize() first.

You have to use FacebookSdk.sdkInitialize(getApplicationContext()); before setContentView(R.layout.activity_main); as documentation states out. In case you need a complete facebook login example, check this one here.