Write an Activity in Android App

+ requirement : give me sources and resources for the activity which is described below. + attachment : [class]FileManager + [activity] Library + Todo + create Floating Action Button on empty activity + activity : extends AppCompatActivity + purpose : add new file about book. + onClick 1. user select txt file for a book 2. user type title and author for the book on popup(alert window) 3. user click OK on the popup 4. save the book as txt file in our format + user input : txt file for a book, title, author + detail + save file about book + format in txt file + seperator between attributes : \n (line seperator) + attributes : title, author, content + content : the text in the file which user selected + default value + title : "" + author : "" + content : "" + directory where we save file : use [class]FileManager - getStorageDir_books(Context context) + file name + first book : [login to view URL] + seconde book : [login to view URL] + ... + reference + [login to view URL] + External storage, Private files