book

Programming Visual Basic .NET, Second Edition

by Jesse Liberty

April 2003

Intermediate to advanced

560 pages

14h 4m

English

O'Reilly Media, Inc.

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About This Book
Part IPart IIPart III
Visual Basic and .NETStepchild No Longer

Examining Your First ProgramClasses and ObjectsNamespacesThe WriteLine( ) MethodComments
Using a Text EditorUsing Visual Studio .NETCreating the “Hello World” programCompiling and running “Hello World”
VB.NET Versus VB6
Working with Built-in TypesChoosing a Built-in TypeConverting Built-in Types
Default ValuesConstantsEnumerationsStrings
Unconditional Branching StatementsConditional Branching StatementsIf StatementsIf . . . Else StatementsNested If StatementsElseIfIIF: If and Only IFSelect Case Statements
Creating Loops with GotoThe Do LoopBreaking Out of a Do LoopThe For LoopControlling a For Loop Using Next
Mathematical OperatorsSimple arithmetic operators (+, -, *, /, \)Self-assignment operatorsThe modulus operator (Mod) to return remaindersThe exponentiation operator (^)String Concatenation Operators (&, +)Relational Operators
Short-Circuit EvaluationOperator Precedence
Creating Models
EncapsulationSpecialization and GeneralizationPolymorphism
Defining ClassesInstantiating ObjectsModules Are ClassesMemory Allocation: The Stack Versus the HeapCreating a Time ClassAccess Modifiers
The Get AccessorThe Set AccessorReadOnly and WriteOnly Properties
Passing Parameters by ValuePassing Parameters by ReferencePassing Reference Types by Value
Specialization and Generalization
Implementing InheritanceCalling Base Class ConstructorsShadowing Base MethodsControlling Access
Creating Polymorphic TypesCreating Polymorphic MethodsVersioning with Overridable and Overrides
Boxing Is ImplicitUnboxing Must Be Explicit
Defining a StructureNo InheritanceNo InitializationPublic Member Data?
Defining an Interface
Testing for Interface ImplementationTypeOf...Is
ArraysDeclaring ArraysThe Size of the ArrayThe ReDim KeywordUnderstanding Default ValuesAccessing Array ElementsThe For Each StatementInitializing Array ElementsThe ParamArray Keyword
Rectangular ArraysJagged Arrays
Default Properties and AssignmentIndexing on Other Values
Array ListsThe Collection ClassQueuesStacks
Creating StringsString LiteralsThe ToString( ) MethodStrings Are Immutable
Comparing StringsConcatenating StringsCopying StringsTesting for EqualityOther Useful String MethodsFinding SubstringsSplitting StringsThe StringBuilder Class
Using Match and MatchCollectionUsing Regex GroupsUsing CaptureCollection
Throwing and Catching ExceptionsThe Throw StatementThe Try and Catch StatementsHow the Call Stack WorksCreating Dedicated Catch StatementsThe Finally StatementException Class Methods and PropertiesCustom Exceptions
DelegatesUsing Delegates to Specify Methods at RuntimeShared DelegatesDelegates as Properties
Publishing and SubscribingEvents and Delegates
Creating a Simple Windows FormUsing NotepadUsing the Visual Studio .NET Designer
Creating the Basic UI FormPopulating the TreeView ControlsTreeNode objectsRecursing through the subdirectoriesGetting the files in the directoryBegin and EndUpdateHandling TreeView EventsClicking the source TreeViewClicking the target TreeViewHandling the Clear button eventImplementing the Copy Button EventGetting the selected filesSorting the list of selected filesHandling the Delete Button Event
Deployment ProjectsSetup ProjectDeployment LocationsCreating a shortcutEntries in My DocumentsShortcuts in the Start menuAdding Special FoldersOther View WindowsMaking changes to the RegistryRegistering file typesManaging the UI during SetupOther View choicesBuilding the Setup Project
Relational Databases and SQLTables, Records, and ColumnsNormalizationDeclarative Referential IntegritySQL
DataTables and DataColumnsDataRelationsRowsData AdapterDBCommand and DBConnectionThe DataAdapter Object
Populating a DataGridCustomizing the DataSetCombining Data Tables
Accessing the DataUpdating a RecordDeleting a RecordCreating New Records
Understanding Web FormsWeb Form EventsPostback versus non-postback eventsStateWeb Form Life Cycle
Setting Initial PropertiesConnecting to the Database
SOAP, WSDL, and DiscoveryServer-Side SupportClient-Side Support
Testing Your Web ServiceViewing the WSDL Contract
PE Files
Modules in the ManifestModule ManifestsOther Required Assemblies
Benefitting from Multi-Module AssembliesBuilding a Multi-Module AssemblyTesting the assemblyLoading the assembly
The End of DLL HellVersionsStrong NamesThe Global Assembly CacheBuilding a Shared AssemblyStep 1: Create a strong nameStep 2: Put the shared assembly in the GAC
AttributesIntrinsic AttributesAttribute targetsApplying attributesCustom AttributesDeclaring an attributeNaming an attributeConstructing an attributeUsing an attribute
Viewing MetaDataType DiscoveryReflecting on a TypeFinding all type membersFinding type methodsFinding particular type membersLate BindingReflection EmitDynamic invocation with InvokeMember( )Dynamic invocation with interfacesDynamic invocation with reflection emit
Application DomainsCreating and Using App DomainsMarshaling Across App Domain BoundariesUnderstanding marshaling with proxiesSpecifying the marshaling method
Context-Bound and Context-Agile ObjectsMarshaling Across Context Boundaries
Understanding Server Object TypesSpecifying a Server with an InterfaceBuilding a ServerBuilding the ClientUsing SingleCallUnderstanding RegisterWellKnownServiceTypeUnderstanding Endpoints
ThreadsStarting ThreadsJoining ThreadsSuspending ThreadsKilling Threads
Using InterlockedUsing the SyncLock StatementUsing Monitors
Race ConditionsDeadlock

Content preview from Programming Visual Basic .NET, Second Edition

Chapter 6. Inheritance and Polymorphism

Chapter 5 demonstrates how to create new types by declaring classes. The current chapter explores the relationship among objects in the real world and how to model these relationships in your code. This chapter focuses on specialization, which is implemented in VB.NET through inheritance. This chapter also explains how instances of more specialized classes can be treated as if they were instances of more general classes, a process known as polymorphism. This chapter ends with a consideration of not inheritable classes, which cannot be specialized, and a discussion of the root of all classes, the Object class, as well as a brief overview of nested classes.

Specialization and Generalization

Classes and their instances (objects) do not exist in a vacuum but rather in a network of interdependencies and relationships, just as we, as social animals, live in a world of relationships and categories. One of the most important relationships among objects in the real world is specialization , which can be described as an is-a relationship. When we say that a Dog is-a mammal, we mean that the dog is a specialized kind of mammal. It has all the characteristics of any mammal (it bears live young, nurses with milk, has hair, etc.), but it specializes these characteristics to the familiar characteristics of canine domesticus. A Cat is also a mammal. As such we expect it to share certain characteristics with the dog that are generalized in Mammal, but to differ ...