<< Chapter < Page Chapter >> Page >

The same thing happens if we do override the draw method but leave the body empty. Therefore, the physical creation of the display window isbeing accomplished in the framework by code outside the draw method. The draw method simply controls the contents of the display window.

Code in the Cars class

Instance variables of type Car

The code in the Cars class (see Listing 2 ) begins by declaring two instance variables of the class named Car . By default, these two instance variables are initialized to null, meaning that they don'tcontain references to objects.

The inherited size method

The setup method begins by calling the method named size , which is inherited from the PApplet class. The documentation for the size method reads partially as follows:

"Defines the dimension of the display window in units of pixels. The size() function must be the first line in setup() . If size() is not used, the default size of the window is 100x100 pixels. The system variables width and height are set by the parameters passed to this function.

Do not use variables as the parameters to size() function, because it will cause problems when exporting your sketch. Whenvariables are used, the dimensions of your sketch cannot be determined during export. Instead, employ numeric values in the size() statement, and then use the built-in width and height variables inside your program when the dimensions of the display window are needed.

The size() function can only be used once inside a sketch, and cannot be used for resizing."

The display window

In case you were wondering about the type of object shown in Image 1 , here is some information from the PApplet documentation.

"This class extends Applet instead of JApplet because 1) historically, we supported Java 1.1, which does not include Swing (without an additional,sizable, download), and 2) Swing is a bloated piece of crap. A Processing applet is a heavyweight AWT component, and can be used the same as any other AWTcomponent, with or without Swing.

Similarly, Processing runs in a Frame and not a JFrame. However, there's nothing to prevent you from embedding a PApplet into a JFrame, it's just thatthe base version uses a regular AWT frame because there's simply no need for Swing in that context. If people want to use Swing, they can embed themselves asthey wish."

Stated differently, the display window that you see in Image 1 is a standard java.awt.Frame object.

Instantiate Car objects

After setting the size of the display window, the setup method in Listing 2 instantiates two objects of the Car class and saves the object's references in the instance variables named myCar1 and myCar2 .

We haven't discussed the constructor for the Car class yet, but we can see in Listing 2 that the constructor for one Car object is passed a color value of pure red and the constructor for the other Car object is passed a color value of pure blue.

Let's talk about color

If you are an experienced Java programmer, what I am about to tell you is going to seem really strange.

Primitive types

As an experienced Java programmer, you know that the Java language defines the following eight primitive types:

Questions & Answers

what is mutation
Janga Reply
what is a cell
Sifune Reply
how is urine form
Sifune
what is antagonism?
mahase Reply
classification of plants, gymnosperm features.
Linsy Reply
what is the features of gymnosperm
Linsy
how many types of solid did we have
Samuel Reply
what is an ionic bond
Samuel
What is Atoms
Daprince Reply
what is fallopian tube
Merolyn
what is bladder
Merolyn
what's bulbourethral gland
Eduek Reply
urine is formed in the nephron of the renal medulla in the kidney. It starts from filtration, then selective reabsorption and finally secretion
onuoha Reply
State the evolution relation and relevance between endoplasmic reticulum and cytoskeleton as it relates to cell.
Jeremiah
what is heart
Konadu Reply
how is urine formed in human
Konadu
how is urine formed in human
Rahma
what is the diference between a cavity and a canal
Pelagie Reply
what is the causative agent of malaria
Diamond
malaria is caused by an insect called mosquito.
Naomi
Malaria is cause by female anopheles mosquito
Isaac
Malaria is caused by plasmodium Female anopheles mosquitoe is d carrier
Olalekan
a canal is more needed in a root but a cavity is a bad effect
Commander
what are pathogens
Don Reply
In biology, a pathogen (Greek: πάθος pathos "suffering", "passion" and -γενής -genēs "producer of") in the oldest and broadest sense, is anything that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ. The term pathogen came into use in the 1880s.[1][2
Zainab
A virus
Commander
Definition of respiration
Muhsin Reply
respiration is the process in which we breath in oxygen and breath out carbon dioxide
Achor
how are lungs work
Commander
where does digestion begins
Achiri Reply
in the mouth
EZEKIEL
what are the functions of follicle stimulating harmones?
Rashima Reply
stimulates the follicle to release the mature ovum into the oviduct
Davonte
what are the functions of Endocrine and pituitary gland
Chinaza
endocrine secrete hormone and regulate body process
Achor
while pituitary gland is an example of endocrine system and it's found in the Brain
Achor
what's biology?
Egbodo Reply
Biology is the study of living organisms, divided into many specialized field that cover their morphology, physiology,anatomy, behaviour,origin and distribution.
Lisah
biology is the study of life.
Alfreda
Biology is the study of how living organisms live and survive in a specific environment
Sifune
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, The processing programming environment. OpenStax CNX. Feb 26, 2013 Download for free at http://cnx.org/content/col11492/1.5
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'The processing programming environment' conversation and receive update notifications?

Ask