Post on 21-Feb-2016
description
transcript
Chapter 5: Programming with C#
1
Microsoft®
Visual C# 2008
Overview
Using ArraysUsing CollectionsUsing Exception Handling Using Interfaces (optional)Using Delegates and Events (optional)
2
Lesson: Using Arrays
3
What Is an Array?
How to Create an Array
How to Initialize and Access Array Members
How to Iterate Through an Array Using the foreach
Statement
How to Use Arrays as Method Parameters
How to Index an Object
What Is an Array?
A data structure that contains a number of variables called elements of
the array
All of the array elements must be of the same type
Arrays are zero indexed
Arrays are objects
Arrays can be:
o Single-dimensional, an array with the rank of one
o Multidimensional, an array with a rank greater than one
o Jagged, an array whose elements are arrays
Array methods
How to Create an Array
Declare the array by adding a set of square brackets to end of the variable
type of the individual elements
Instantiate to create
o int[ ] numbers = new int[5];
To create an array of type Object
o object [ ] animals = new object [100];
Int[] MyIntegerArray;
type[] array-name;
Syntax
Example
How to Initialize and Access Array Members
string[] animal = {"Mouse", "Cat", "Lion"};
animal[1]= "Elephant";
string someAnimal = animal[2];
int[] numbers = {10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0};
numbers[4] = 5;
Initializing an array
Accessing array members
How to Iterate Through an Array Using the foreach Statement
int[] numbers = {4, 5, 6, 1, 2, 3, -2, -1, 0};
foreach (int i in numbers) {
Console.WriteLine(i);
}
Using foreach statement repeats the embedded statement(s) for each
element in the array
foreach ( type identifier in expression ) statement-block
Syntax
Examples
How to Use Arrays as Method Parameters
8
Pass an array to a method
Use the params keyword to pass a variable number of arguments to a
method
public int Sum(params int[] list) {int total = 0;foreach ( int i in list ) {
total += i;}return total;
}...// pe is the object providing Sum()...int value = pe.Sum( 1, 3, 5, 7, 9, 11 );
How to Index an Object
9
Use this keyword, and get and set accessors
public class Zoo {private Animal[] theAnimals;public Animal this[int i] {
get {return theAnimals[i];
}set {
theAnimals[i] = value;}
}}
10
Practice: Using a foreach Statement with an Array
In this practice, you will create an array, populate it, and use the foreach statement to print out the values in the array
Hands-on Practice
11
Practice (optional): Using an Indexer
In this practice, you will write an indexer for the Zoo class
Hands-on Practice
Lesson: Using Collections
12
What Are Lists, Queues, Stacks, and Hash Tables?
How to Use the ArrayList Class
How to Use Queues and Stacks
How to Use Hash Tables
What Are Lists, Queues, Stacks, and Hash Tables?
13
Lists, queues, stacks, and hash tables are common ways to manage data
in an application
List: A collection that allows you access by index
Example: An array is a list; an ArrayList is a list
Queue: First-in, first-out collection of objects
Example: Waiting in line at a ticket office
Stack: Last-in-first-out collection of objects
Example: A pile of plates
Hash table: Represents a collection of associated keys and
values
organized around the hash code of the key
Example: A dictionary
How to Use the ArrayList Class
14
ArrayList does not have a fixed size; it grows as needed
Use Add(object) to add an object to the end of the ArrayList
Use [] to access elements in the ArrayList
Use TrimToSize() to reduce the size to fit the number of elements in the ArrayList
Use Clear to remove all the elements
Can set the capacity explicitly
How to Use Queues and Stacks
15
Queues: first-in, first-out
o Enqueue places objects in the queue
o Dequeue removes objects from the queue
Stacks: last-in, first-out
o Push places objects on the stack
o Pop removes objects from the stack
o Count gets the number of objects contained in a stack or queue
How to Use Hash Tables
16
Book techBook = new Book("Inside C#", 0735612889);
// ...
public Hashtable bookList;
//
bookList.Add(0735612889, techBook);
//
Book b = (Book) bookList[0735612889];
// b’s title is "Inside C#”
A hash table is a data structure that associates a key with an object, for rapid retrieval
Key Object
17
Practice: Creating and Using Collections
In this practice, you will use the ArrayList class
Hands-on Practice
Lesson: Using Exception Handling
18
How to Use Exception Handling
How to Throw Exceptions
How to Use Exception Handling
19
Exception handling syntax
try {
// suspect code
}
catch {
// handle exceptions
}
finally {
// always do this
}
How to Throw Exceptions
20
Throw keyword
Exception handling strategies
Exception types
The predefined common language runtime exception classes
Example: ArithmeticException, FileNotFoundException
User-defined exceptions
21
Practice: Using Exception Handling
In this practice, you will use throw and catch an exception
Hands-on Practice
Lesson: Using Interfaces (optional)
22
What Is an Interface?
How to Use an Interface
How to Work with Objects That Implement Interfaces
How to Inherit Multiple Interfaces
Interfaces and the .NET Framework
What Is an Interface?
23
Is a reference type that defines a contract
Specifies the members that must be supplied by classes or
interfaces that implement the interface
Can contain methods, properties, indexers, events
Does not provide implementations for the members
Can inherit from zero or more interfaces
An interface:
How to Use an Interface
24
interface ICarnivore {
bool IsHungry { get; }
Animal Hunt();
void Eat(Animal victim);
}
An interface defines the same functionality and behavior to unrelated
classes
Declare an interface
Implement an interface
How to Work with Objects That Implement Interfaces
25
if ( anAnimal is ICarnivore ) {ICarnivore meatEater = (ICarnivore) anAnimal;Animal prey = meatEater.Hunt();meatEater.Eat( prey );
}
is
ICarnivore meatEater = anAnimal as ICarnivore;if ( meatEater != null ) {
Animal prey = meatEater.Hunt();meatEater.Eat( prey );
}
as
// is and as with an objectif ( prey is Antelope ) { ... }
How to Inherit Multiple Interfaces
26
Interfaces should describe a type of behavior
Examples:
o Lion is-a-kind-of Animal; Lion has Carnivore behavior
o Shark is-a-kind-of Animal; has Carnivore behavior
o Derive Lion and Shark from abstract class Animal
o Implement Carnivore behavior in an Interface
Class Chimpanzee : Animal, ICarnivore, IHerbivore { … }
Interfaces and the .NET Framework
27
Allows you to make your objects behave like .NET Framework objects
Example: Interfaces used by Collection classes
o ICollection, IComparer, IDictionary, IDictionary Enumerator,
o IEnumerable, IEnumerator, IHashCodeProvider, IList
public class Zoo : IEnumerable {
. . .
public IEnumerator GetEnumerator() {
return (IEnumerator)new ZooEnumerator(
this );
}
28
Practice: Using Interfaces
In this practice, you will implement the ICloneable interface
Hands-on Practice
Lesson: Using Delegates and Events
29
How to Create a Delegate
What Is an Event?
How to Write an Event Handler
How to Create a Delegate
30
Medical CenterScheduleApointment
CallsProcessNextPatient
DelegateAppointmentType
Zoo Keeper 1Schedule lion CheckClaws
Zoo Keeper 1Schedule lion CheckClaws
AntelopeCheckHooves
LionCheckClaws
What Is an Event?
31
Mouse and keyboard
MouseDown,MouseUp,MouseMove,MouseEnter,MouseLeave,MouseHover
KeyPress, KeyDown, KeyUp
Property
FontChangedSizeChangedCursorChanged
How to Write an Event Handler
32
Declare events using delegateso System.EventHandler is declared as a delegate
button1.Click += new System.EventHandler(button1_Click);
Event handler is called when the event occurso EventArgs parameter contains the event data
private void button1_Click(object sender, System.EventArgs e) {MessageBox.Show( e.ToString() );
}
33
Practice: Declaring and Calling a Delegate
In this practice, you will create and use a delegate
Hands-on Practice
Review
34
Using Arrays
Using Collections
Using Exception Handling
Using Interfaces
Using Delegates and Events
35
Lab 5:1: Using Arrays
Exercise 1: Sorting Numbers in an Array
36
Lab 5.2 (optional): Using Indexers and Interfaces
Exercise 1: Writing the Check Pick-up Application Exercise 2: Using Interfaces
37
Lab 5.3 (optional): Using Delegates and Events
Exercise 1: Working with Events and Delegates