Processing: Creative Coding and Computational Art

The entire SportsGear interface in Processing would be:
interface SportsGear{
String getBrandName();
float getUnitCost();
void setUnitCost(float unitCost);
void printWarranty();
}
It’s pretty simple to create interfaces. However, using them is a bit trickier, and using them
polymorphically is trickier still. We’ll take it one step at a time. Here’s a Bicycle class that
extends a Vehicle class and implements the SportsGear interface (this code is not meant
to be run):
class Bicycle extends Vehicle implements SportsGear{
//instance variables
String brandName;
float unitCost;
// constructor
Bicycle(String brandName, float unitCost){
this.brandName = brandName;
this.unitCost = unitCost;
}
/* We're required to implement all methods
from the SportsGear interface*/
String getBrandName(){
return brandName;
}
float getUnitCost(){
return unitCost;
}
void setUnitCost(float unitCost){
this.unitCost = unitCost;
}
void printWarranty(){
println("Bicycle: full replacement value for 1 year");
}
}
OBJECT-ORIENTED PROGRAMMING
To keep things simple in the example, I didn’t bother adding any properties or methods to
the Vehicle class, or extra properties/methods to the Bicycle class. Instead, the Bicycle
class gets all of its members just by implementing the SportsGear interface. Whenever a
class implements an interface—through the use of the implements keyword—the class
must implement all the methods in the interface, which means that it needs to include all
the method definitions contained within the interface, as well as fill in the method blocks.
This is enforced by the compiler, which will generate an error if it’s not done.
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