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An earlier module titled Getting Started provided information on howto get started programming with Microsoft's XNA Game Studio.

The three main characteristics of an object-oriented program

Object-oriented programs exhibit three main characteristics:

  • Encapsulation
  • Inheritance
  • Polymorphism

In this and the next two modules, I will explain and illustrate those three characteristics plus some related topics.

Viewing tip

I recommend that you open another copy of this module in a separate browser window and use the following links to easily find and view the Figuresand Listings while you are reading about them.


  • Figure 1 . Output from the program named Props01.


  • Listing 1 . Beginning of the class named Props01.
  • Listing 2 . Beginning of the class named TargetClass.
  • Listing 3 . Call the object's public accessor methods.
  • Listing 4 . Definition of setColor and getColor methods in TargetClass.
  • Listing 5 . Set, get, and display a property value with a valid value.
  • Listing 6 . The set Accessor and get Accessor methods for the property named height.
  • Listing 7 . Call manipulator method and display results.
  • Listing 8 . A simple manipulator method named doubleHeight.
  • Listing 9 . Set and get the property named height with an invalid value.
  • Listing 10 . Pause until the user presses any key.
  • Listing 11 . The program named Props01.

General background information

In addition to the three explicit characteristics of encapsulation, inheritance, and polymorphism, an object-oriented program also has an implicitcharacteristic of abstraction .


Abstraction is the process by which we specify a new data type, often referred to as an abstract data type or ADT. This includes a specification ofthe type's data representation and its behavior. In particular,

  • What kind of data can be stored in an entity of the new type?
  • What are all the ways that the data can be manipulated?

How does abstraction relate to encapsulation?

Encapsulation is the process of gathering an ADT's data representation and behavior into one encapsulated entity. In other words, encapsulation convertsfrom the abstract to the concrete .

Some analogies

You might think of this as being similar to converting an idea for an invention into a set of blueprints from which it can be built, or converting aset of written specifications for a widget into a set of drawings that can be used by the machine shop to build the widget.

Automotive engineers encapsulated the specifications for the steering mechanism of my car into a set of manufacturing drawings. Then manufacturingpersonnel used those drawings to produce an object where they exposed the interface (steering wheel) and hid the implementation (levers, bolts, etc.).

In all likelihood, the steering mechanism contains a number of other more-specialized embedded objects, each of which has state and behavior and eachof which also has an interface and an implementation.

The interfaces for those embedded objects aren't exposed to me, but they are exposed to the other parts of the steering mechanism that use them.

Questions & Answers

can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
Commplementary angles
Idrissa Reply
im all ears I need to learn
right! what he said ⤴⤴⤴
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
Dearan Reply
kkk nice
Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
is it 3×y ?
Joan Reply
J, combine like terms 7x-4y
Bridget Reply
im not good at math so would this help me
Rachael Reply
I'm not good at math so would you help me
what is the problem that i will help you to self with?
how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Xna game studio. OpenStax CNX. Feb 28, 2014 Download for free at https://legacy.cnx.org/content/col11634/1.6
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