Cross Ref > OOP Basics

The Object class is Java's single base class all classes ultimately inherit from.

public class Cyborg {

}

public class Cyborg extends Object {

}

In C#, the Object keyword is an alias for the base System.Object class and is the single base class all classes ultimately inherit from.

Syntax Example:   //Specify both namespace and class: public class Cyborg : System.Object { } //Use shortcut alias: public class Cyborg : Object { } //None, default is System.Object public class Cyborg { }

Unlike languages such as C++ and Object Pascal, every line of code written in Java must occur within a class.

//Declare class.

public class Cyborg {

  //Fields.

  private String cyborgName;

  private int age;

  //Constructor.

  public Person() {

  cyborgName = "unknown";

  age = 0;

  }

}

//Create object from class.

Cyborg p = new Cyborg();

p.getClass(); //From the Object base class.

In C#, you use the class keyword to specify a class and you signify its parent with a colon and the name of the parent class. When you instantiate an object from a class, you use the new keyword.

public class Cyborg : System.Object
{
  public virtual void IntroduceYourself()
  {
    MessageBox.Show("Hi, I do not have a name yet.");  
  }
}

Cyborg T1 = new Cyborg();
T1.IntroduceYourself();

//No need to clean up with managed classes.

//The garbage collector will take care of it.

 C# Class..Object (class...new)  

Simple syntax example of class inheritance.

public class Android {

}

public class T-600 extends Android {

}

 Java Inheritance (extends ParentClass)

In C#, you use the class keyword followed by the parent class after a colon. If you leave out the parent class, your class inherits from System.Object.

public class Android

{

}

public class T-600 : Android

{

}

 C# Inheritance (: ParentClass)

In Java, you can set the scope of a field member to public, protected, or private. Additional modifiers are static, abstract, final (assign only once), strictfp (strict floating point values) transient (do not save to persistent storage), and volatile (all threads see same value).

You can initialize member fields as in:

int age = 0;

In C# you can set the visibility of a member field to any visibility: private, protected, public, internal or protected internal.

You can intialize a member field with a default when declared. If you set the member field value in your constructor, it will override the default value.

Finally, you can use the static modifier (no instance required) and readonly modifier (similar to a constant).

public class Cyborg : System.Object
{

  private string serialNumber = "A100";

  public string cyborgName; 
  public int cyborgAge = 0;
  public static readonly int seriesID = 100;
}

 C# Member Field  

In C#, you indicate a method with parens, no parens indicates a member property. Use the void return type for methods that do not return a value.

public class Cyborg : System.Object
{
  public virtual void IntroduceYourself()
  {
    MessageBox.Show("Hi, I do not have a name yet.");  
  }
}

Cyborg T1 = new Cyborg();
T1.IntroduceYourself();

 C# Member Method

The method modifiers are abstract, extern, new, partial, sealed, virtual, and override. Specify C# member modifiers as follows:

abstract SomeMethod() {..}

The field modifiers are const, readonly, static, volatile. Specify field modifiers as follows:

readonly int MyAge;

In C#, parens indicate a method and the lack of parens indicate a property. You use special get and set methods to both get and set the values of properties.

C# 3.0 introduced auto-implemented properties for use when no additional logic is required.

pulic int VendorID {get; set;}

For a read-only property, leave out the set method.

The value keyword is used to refer to the member field. Properties can make use of any of the access modifiers (private, protected, etc). It is common to use a lowercase member names for member fields ("name" in our example) and uppercase properties to manage member fields ("Name" in our example).

public class Cyborg : System.Object
{
  private string cyborgName;

 
  public string CyborgName
  {
    get {return cyborgName;}
    set {cyborgName = value;}
  }
}

 C# Member Property (no (), get, set)  

In C#, you specify each class and each class member's visibility with an access modifier. The C# access modifiers are the traditional public, protected, and private plus the two additional .Net modifiers internal and protected internal.

Internal indicates members are accessible from types in the same assembly. Protected internal indicates members are accessible from types in the same assembly as well as descendant classes. OO purist might object to internal and protected internal and I suggest you choose private, protected, or public over them until you both fully understand them and have a need that is best suited by them.

public class Cyborg

{

private String FName;

}

 C# Access Modifiers