Processing: Creative Coding and Computational Art

println();
}
}
This method may look complex at first glance, but it is really just a bunch of if statements
sending output to the text window. One thing that is new in the method is the use of the
keyword null in some of the if statements. For example
if (this.tortillaFlavor!=null){
The conditional expression != means “is not equal to.” So the if statement is then true
when this.tortillaFlavor is not equal to null. This type of logic can seem tricky when
you first start using it. Just try to remember that if statements are checking if the condition
between the parentheses is true, not for a universal truth. So, if I say ira = tall (I’m
not really), then the conditional if (ira==tall) would evaluate to true, as would if
(ira!=short). To explain why I used the null keyword in the first place, I need to go back
to the discussion about declaring variables/properties.
Notice that in the class, when I declare a property using the String data type, that String
has an initial cap. (Remember that Java and Processing are case sensitive, so the capital S
matters.) Also, throughout the book, when variables of a primitive type have been
declared—such as int or float—all lowercase letters were used. The capital S in String
should inform you that the String data type is a class. Variables or properties declared of
type String, or of any class for that matter, are not primitive types like int, float, or
boolean that actually evaluate to specific values, but instead are object reference variables
that evaluate to the memory address where the objects are stored. Now you don’t need to
worry about memory addresses. But what you do need to know is that the default value of
an object reference, once it has been declared and before it has been defined, is null.
In the printRecipe() method, I needed to find a way to keep the program from crashing
when it couldn’t a find a value it expected. By writing the if statements the way I did, I
ensured that if the property was initialized, and therefore wasn’t equal to null, the block
of code would run. However, if it was still equal to null, then the relevant print statement
would be skipped, keeping the program from crashing. This is actually a pretty common
thing to do in coding, and you will see more of it later on in the book.
Throughout the method, I also used the concatenation operator, +, to join the string literals
in quotes with the properties. Remember, literals are just actual words or numbers that
you write—for example, “art” (a string literal) or 10 (a number literal, which is referred to
as a constant). A literal’s meaning or value is explicitly what is written. To join a literal with
a property or variable, you need to use the concatenation operator, as follows:
this.beanType + " beans and white wine."
Also notice within the method that most of the if statements are nested within an outer
if statement, which determines if there is a tortilla. If there isn’t a tortilla, then the program
skips the remaining statements and outputs the following:
"Uh, you'll need to give me some ingredients if you actually want me
to produce a recipe."
OBJECT-ORIENTED PROGRAMMING
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