Tool Bar Title at center

Hello,

i am getting stuck into the toolbar title aliging. i want to make the toolbar title at center. I am using the master Details Page.
Every time i am getting the toolbar null.

var toolbar = FindViewById<Android.Support.V7.Widget.Toolbar>(Resource.Id.toolbar);

var actionBar = ((Android.App.Activity)Context).ActionBar;

private static MainActivity _this;

    public static View RootFindViewById<T>(int id) where T : View
    {
        return _this.FindViewById<T>(id);
    }

    public MainActivity()
    {
        _this = this;
    }

i have used all of the above methods and properties but still getting toolbar null.

Please suggest.