XML : Rendering problems while implementing Facebook

I am trying to implement facebook login into my app seeingn this link

I am seeing lots of Rendering problems and some Exception in my xml file.

This is my xml

fragment_main.xml

  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"      xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"      android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"      android:paddingRight="@dimen/activity_horizontal_margin"      android:orientation="vertical"      android:paddingTop="@dimen/activity_vertical_margin"      android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivityFragment">        <TextView          android:layout_width="fill_parent"          android:layout_height="wrap_content"          android:text="New Text"          android:id="@+id/textView"          android:layout_centerHorizontal="true"/>        <com.facebook.login.widget.LoginButton          android:id="@+id/login_button"          android:layout_width="fill_parent"          android:layout_height="wrap_content" />      </LinearLayout>    

The error is as below

  Rendering Problems The following classes could not be found:    The following classes could not be instantiated :   - android.support.v7.internal.app.WindowDecorActionBar (Fix Build Path, Create Class)     Tip: Try to build the project.  The following classes could not be instantiated:      The following classes could not be instantiated :   - com.facebook.login.widget.LoginButton (Open Class, Show Exception, Clear Cache)     Tip: Use View.isInEditMode() in your custom views to skip code or show sample data when shown in the IDE      Exception Details java.lang.NoClassDefFoundError: Could not initialize class com.facebook.login.widget.LoginButton   at java.lang.reflect.Constructor.newInstance(Constructor.java:422)   at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)   at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:835)   at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:70)   at android.view.LayoutInflater.rInflate(LayoutInflater.java:811)   at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)   at android.view.LayoutInflater.inflate(LayoutInflater.java:515)   at android.view.LayoutInflater.inflate(LayoutInflater.java:394)    

What is this Rendering problem???

Whenever i start any project i'll end up with this Rendering Problem

Please help me with this project, thanks in advance.