C# Programming: Object-Oriented Features and Component-Based Development, Slides of Advanced Computer Programming

Download C# Programming: Object-Oriented Features and Component-Based Development and more Slides Advanced Computer Programming in PDF only on Docsity! C# Programming: From Problem Analysis to Program Design 1 Advanced Object-Oriented Programming Features C# Programming: From Problem Analysis to Program Design 3rd Edition 11 Docsity.com C# Programming: From Problem Analysis to Program Design 2 Chapter Objectives • Learn the major features of object-oriented languages • Design and develop multitier applications using component-based development methods • Use inheritance to extend the functionality of user- defined classes • Create abstract classes that include abstract methods Docsity.com C# Programming: From Problem Analysis to Program Design 5 Object-Oriented Language Features • Abstraction – Abstract or identify the objects involved in the problem • Encapsulation – Packaging data and behaviors into a single unit • Inheritance – Reuse of code through extending program units • Polymorphism – Multiple implementations of the same behaviors Docsity.com C# Programming: From Problem Analysis to Program Design 6 Component-Based Development Figure 11-1 Component-based development Docsity.com C# Programming: From Problem Analysis to Program Design 7 Component-Based Development (continued) • Multitier applications – Data access tier for accessing data from text files and databases – Graphical user interface tier for user interaction • Windows • Web • Components implemented through classes in C# • Class library files with a dynamic link library (DLL) extension Docsity.com C# Programming: From Problem Analysis to Program Design 10 Inheriting from Other .NET FCL Classes • Add functionality to programs with minimal programming • Extend System.Windows.Forms.Form class to build GUIs (Button, Label, TextBox, ListBox) Base class Derived class Figure 11-3 Derived class Docsity.com C# Programming: From Problem Analysis to Program Design 11 Creating Base Classes for Inheritance • Can define your own classes from which other classes can inherit • Base class is called the super or parent class • Data members are defined with a private access modifier • Constructors are defined with public access modifiers • Properties offer public access to data fields Docsity.com C# Programming: From Problem Analysis to Program Design 12 Overriding Methods • Replace the method defined at a higher level • Keyword override included in derived class – Base method includes virtual, abstract, or override keyword • Overriding differs from overloading a method – Overridden methods have exactly the same signature – Overloaded methods each have a different signature Figure 11-4 ToString( ) signature Docsity.com C# Programming: From Problem Analysis to Program Design 15 Using Members of the Base Class • Scope – Methods defined in subclass take precedence when named the same name as member of a parent class • Can call an overridden method of the base class – Use keyword base before the method name return base.GetSleepAmt( ) // Calls GetSleepAmt( ) in // parent class Docsity.com C# Programming: From Problem Analysis to Program Design 16 Relationship between the Person and Student Classes Figure 11-5 Inheritance class diagram Docsity.com C# Programming: From Problem Analysis to Program Design 17 Making Stand-Alone Components • Compile class and create an assembly – Assemblies are units configured and deployed in .NET • Classes can be compiled and stored as a dynamic link library (DLL) instead of into the EXE file type • Adds a reference to the DLL – That referenced file with the .dll extension becomes part of the application’s private assembly Docsity.com C# Programming: From Problem Analysis to Program Design 20 Add Reference to Base Class Figure 11-8 Adding a reference to a DLL One of the first things to do is Add a Reference to the Parent DLL Docsity.com C# Programming: From Problem Analysis to Program Design 21 Add Reference to Base Class (continued) Figure 11-9 Add Reference dialog box Use Browse button to locate DLL Docsity.com C# Programming: From Problem Analysis to Program Design 22 Add Reference to Base Class (continued) Figure 11-10 Locating the Person.dll component Docsity.com C# Programming: From Problem Analysis to Program Design 25 Creating a Client Application to Use the DLL • DLL components can be reused with many different applications • Two steps – Add a reference to the DLL components – Include a using statement with the namespace • Then declare an object of the component type(s) • Use members of the derived, base, or referenced classes Docsity.com C# Programming: From Problem Analysis to Program Design 26 Creating a Client Application to Use the DLL (continued) Figure 11-12 DLLs referenced in the PresentationGUI class Docsity.com C# Programming: From Problem Analysis to Program Design 27 Creating a Client Application to Use the DLL (continued) Figure 11-13 PresentationGUI output referencing two DLLs Docsity.com