public MainWindowViewModel() { /* * create book collection and add three example books */ BookCollection MyBookCollection = new BookCollection(); MyBookCollection.Add(new Book()); MyBookCollection.ElementAt <Book>(0).Author = "Lars Raschke"; MyBookCollection.ElementAt <Book>(0).Title = "How to program last minute"; MyBookCollection.ElementAt <Book>(0).Edition = 1; MyBookCollection.ElementAt <Book>(0).PubYear = 2018; MyBookCollection.ElementAt <Book>(0).Available = true; MyBookCollection.Add(new Book()); MyBookCollection.ElementAt <Book>(1).Author = "Dieter Bohlen"; MyBookCollection.ElementAt <Book>(1).Title = "Weg zum Erfolg"; MyBookCollection.ElementAt <Book>(1).Edition = 3; MyBookCollection.ElementAt <Book>(1).PubYear = 1995; MyBookCollection.ElementAt <Book>(1).Available = false; MyBookCollection.Add(new Book()); MyBookCollection.ElementAt <Book>(2).Author = "Beate Uhse"; MyBookCollection.ElementAt <Book>(2).Title = "Gummibaum statt Gummifrauen"; MyBookCollection.ElementAt <Book>(2).Edition = 2; MyBookCollection.ElementAt <Book>(2).PubYear = 2010; MyBookCollection.ElementAt <Book>(2).Available = true; // create a wrapped book collection of the book collection MyWrappedBookCollection = new BookCollectionViewModel(MyBookCollection); // creating RelayCommands with the given methods openFileDialogCommand = new RelayCommand(OpenNewFileDialog); exitApplicationCommand = new RelayCommand(ExitCurrentApplication); addNewBookCommand = new RelayCommand(() => Messenger.Instance.Send <OpenNewBookWindowMessage>(new OpenNewBookWindowMessage())); }