Csharp/CSharp Tutorial/Class/Object Reference
Содержание
- 1 Assign values to the House object"s fields using object renerence
- 2 Change the object referenced by the myHouse object reference to the object referenced by yourHouse
- 3 Class comparison
- 4 Creating a House object and assigning its memory location to myHouse
- 5 Declare a House object reference named myHouse
- 6 Declare another House object reference and create another House object
- 7 Declare class fields and methods
- 8 Display the field values using object reference
- 9 Pass reference type variable without "out" and "ref"
- 10 Reference an object by interface and class
- 11 Reference a static member function without using the class name
- 12 Reference equals
- 13 Reference one object by multiple interfaces
- 14 Reference type equals: complex number
- 15 Use interface as reference
Assign values to the House object"s fields using object renerence
<source lang="csharp">class House {
public string make;
public string model;
public string color;
public int yearBuilt;
public void Start()
{
System.Console.WriteLine(model + " started");
}
public void Stop()
{
System.Console.WriteLine(model + " stopped");
}
} class MainClass {
public static void Main()
{
House myHouse;
myHouse = new House();
myHouse.make = "ABC";
myHouse.model = "Apartment";
myHouse.color = "black";
myHouse.yearBuilt = 1995;
}
}</source>
Change the object referenced by the myHouse object reference to the object referenced by yourHouse
<source lang="csharp">class House {
public string make;
public string model;
public string color;
public int yearBuilt;
public void Start()
{
System.Console.WriteLine(model + " started");
}
public void Stop()
{
System.Console.WriteLine(model + " stopped");
}
} class MainClass {
public static void Main()
{
House myHouse;
myHouse = new House();
myHouse.Start();
myHouse.Stop();
House yourHouse = new House();
yourHouse.make = "AAA";
yourHouse.model = "VVV";
yourHouse.color = "red";
yourHouse.yearBuilt = 2000;
System.Console.WriteLine("yourHouse is a " + yourHouse.model);
System.Console.WriteLine("Assigning yourHouse to myHouse");
myHouse = yourHouse;
System.Console.WriteLine("myHouse details:");
System.Console.WriteLine("myHouse.make = " + myHouse.make);
System.Console.WriteLine("myHouse.model = " + myHouse.model);
System.Console.WriteLine("myHouse.color = " + myHouse.color);
System.Console.WriteLine("myHouse.yearBuilt = " + myHouse.yearBuilt);
}
}</source>
started stopped yourHouse is a VVV Assigning yourHouse to myHouse myHouse details: myHouse.make = AAA myHouse.model = VVV myHouse.color = red myHouse.yearBuilt = 2000
Class comparison
<source lang="csharp">using System;
class ComparingRelations
{
static void Main(string[] args)
{
int a = 12;
int b = 12;
Console.WriteLine( a == b );
Console.WriteLine( (object)a == (object)b );
string c = "hello";
string d = "hello";
Console.WriteLine( (object) c==(object) d );
ClassCompare x = new ClassCompare();
ClassCompare y;
x.val = 1;
y = x;
Console.WriteLine( x == y );
x.val = 2;
Console.WriteLine( y.val.ToString() );
}
}
class ClassCompare
{
public int val = 0;
}</source>
Creating a House object and assigning its memory location to myHouse
<source lang="csharp">public class House {
public string make;
public string model;
public string color;
public int yearBuilt;
public void Start()
{
System.Console.WriteLine(model + " started");
}
public void Stop()
{
System.Console.WriteLine(model + " stopped");
}
} class MainClass {
public static void Main()
{
House myHouse;
myHouse = new House();
}
}</source>
Declare a House object reference named myHouse
<source lang="csharp">public class House {
public string make;
public string model;
public string color;
public int yearBuilt;
public void Start()
{
System.Console.WriteLine(model + " started");
}
public void Stop()
{
System.Console.WriteLine(model + " stopped");
}
} class MainClass {
public static void Main()
{
House myHouse;
System.Console.WriteLine("Creating a House object and assigning its memory location to myHouse");
myHouse = new House();
}
}</source>
Creating a House object and assigning its memory location to myHouse
Declare another House object reference and create another House object
<source lang="csharp">class House {
public string make;
public string model;
public string color;
public int yearBuilt;
public void Start()
{
System.Console.WriteLine(model + " started");
}
public void Stop()
{
System.Console.WriteLine(model + " stopped");
}
} class MainClass {
public static void Main()
{
House myHouse;
myHouse = new House();
myHouse.Start();
myHouse.Stop();
House yourHouse = new House();
yourHouse.make = "AQW";
yourHouse.model = "SSS";
yourHouse.color = "red";
yourHouse.yearBuilt = 2000;
System.Console.WriteLine("yourHouse is a " + yourHouse.model);
}
}</source>
started stopped yourHouse is a SSS
Declare class fields and methods
- The new operator dynamically allocates memory for an object and returns a reference to it.
- This reference is, more or less, the address in memory of the object allocated by new.
- This reference is then stored in a variable.
<source lang="csharp">public class House
{
public string make;
public string model;
public string color;
public int yearBuilt;
public void Start()
{
System.Console.WriteLine(model + " started");
}
public void Stop()
{
System.Console.WriteLine(model + " stopped");
}
} class MainClass {
public static void Main()
{
House myHouse;
System.Console.WriteLine("Creating a House object and assigning its memory location to myHouse");
myHouse = new House();
}
}</source>
Creating a House object and assigning its memory location to myHouse
Display the field values using object reference
<source lang="csharp">class House {
public string make;
public string model;
public string color;
public int yearBuilt;
public void Start()
{
System.Console.WriteLine(model + " started");
}
public void Stop()
{
System.Console.WriteLine(model + " stopped");
}
} class MainClass {
public static void Main()
{
House myHouse;
myHouse = new House();
myHouse.make = "ABC";
myHouse.model = "Apartment";
myHouse.color = "black";
myHouse.yearBuilt = 1995;
System.Console.WriteLine("myHouse details:");
System.Console.WriteLine("myHouse.make = " + myHouse.make);
System.Console.WriteLine("myHouse.model = " + myHouse.model);
System.Console.WriteLine("myHouse.color = " + myHouse.color);
System.Console.WriteLine("myHouse.yearBuilt = " + myHouse.yearBuilt);
}
}</source>
myHouse details: myHouse.make = ABC myHouse.model = Apartment myHouse.color = black myHouse.yearBuilt = 1995
Pass reference type variable without "out" and "ref"
<source lang="csharp">using System; class MyClass {
public int Val = 20;
} class MainClass {
static void MyMethod(MyClass myObject, int intValue)
{
myObject.Val = myObject.Val + 5;
intValue = intValue + 5;
}
static void Main()
{
MyClass myObject = new MyClass();
int intValue = 10;
Console.WriteLine("Before -- myObject.Val: {0}, intValue: {1}", myObject.Val, intValue);
MyMethod(myObject, intValue);
Console.WriteLine("After -- myObject.Val: {0}, intValue: {1}", myObject.Val, intValue);
}
}</source>
Before -- myObject.Val: 20, intValue: 10 After -- myObject.Val: 25, intValue: 10
Reference an object by interface and class
- You can create an interface reference variable.
- Such a variable can refer to any object that implements its interface.
- When you call a method on an object through an interface reference, the method is the version of the method implemented by the object.
<source lang="csharp">public interface Player
{
void PlayMusic();
} public class Student : Player {
public void PlayMusic(){}
public void DoALittleDance(){}
} public class MainClass {
static void Main()
{
Student st = new Student();
Player musician = st;
musician.PlayMusic();
st.PlayMusic();
st.DoALittleDance();
}
}</source>
Reference a static member function without using the class name
<source lang="csharp">public class A {
public static void SomeFunction()
{
System.Console.WriteLine( "SomeFunction() called" );
}
static void Main()
{
A.SomeFunction();
SomeFunction();
}
}</source>
SomeFunction() called SomeFunction() called
Reference equals
<source lang="csharp">public class MyClass {
public MyClass( )
{
}
} public class MainClass {
static void Main()
{
MyClass referenceA = new MyClass( );
MyClass referenceB = new MyClass( );
System.Console.WriteLine( "Result of Equality is {0}", referenceA == referenceB );
}
}</source>
Result of Equality is False
Reference one object by multiple interfaces
<source lang="csharp">using System; interface Interface1 {
void PrintOut(string s);
} interface Interface2 {
void PrintOut(string s);
} class MyClass : Interface1, Interface2 {
public void PrintOut(string s)
{
Console.WriteLine(s);
}
} class MainClass {
static void Main()
{
MyClass mc = new MyClass();
Interface1 ifc1 = (Interface1)mc;
Interface2 ifc2 = (Interface2)mc;
mc.PrintOut("object.");
ifc1.PrintOut("interface 1.");
ifc2.PrintOut("interface 2.");
}
}</source>
object. interface 1. interface 2.
Reference type equals: complex number
<source lang="csharp">public class ComplexNumber {
public ComplexNumber( int real, int imaginary )
{
this.real = real;
this.imaginary = imaginary;
}
public override bool Equals( object obj )
{
ComplexNumber other = obj as ComplexNumber;
if( other == null )
{
return false;
}
return (this.real == other.real) && (this.imaginary == other.imaginary);
}
public override int GetHashCode()
{
return (int) real ^ (int) imaginary;
}
public static bool operator==( ComplexNumber me, ComplexNumber other )
{
return Equals( me, other );
}
public static bool operator!=( ComplexNumber me, ComplexNumber other )
{
return Equals( me, other );
}
private double real;
private double imaginary;
} public class MainClass {
static void Main()
{
ComplexNumber referenceA = new ComplexNumber( 1, 2 );
ComplexNumber referenceB = new ComplexNumber( 1, 2 );
System.Console.WriteLine( "Result of Equality is {0}",referenceA == referenceB );
System.Console.WriteLine( "Identity of references is {0}",(object) referenceA == (object) referenceB );
System.Console.WriteLine( "Identity of references is {0}",ReferenceEquals(referenceA, referenceB) );
}
}</source>
Result of Equality is True Identity of references is False Identity of references is False
Use interface as reference
<source lang="csharp">using System; interface Interface1 {
void PrintOut(string s);
} class MyClass : Interface1 {
public void PrintOut(string s)
{
Console.WriteLine("Calling through: {0}", s);
}
} class MainClass {
static void Main()
{
MyClass mc = new MyClass();
mc.PrintOut("object.");
Interface1 ifc = (Interface1)mc;
ifc.PrintOut("interface.");
}
}</source>
Calling through: object. Calling through: interface.
