Object-Oriented Programming (OOP)

Objects

• In software, objects are collections of data that include states and behaviors.
  • States: Changable attributes of the object. Stored in fields (variables in many languages).
  • Behaviors: Functions/methods that perform based on the object’s state.
  • Data encapsulation: Principle of OOP where an object’s state is only expressed/interacted with via behaviors.
• Advantages of OOP include:

  • Reusability of code

  • Portability of code to other code bases

  • Obscurity of internal data (as interactions happen on outer functional bases)

  • Can be replaced with other objects as needed

Classes

• In programming, a class is a category of objects– an individual object may be an instance of a given class.

• Classes are not independent applications, but are declared and called.

• Declarations include:

  • Modifiers for access

  • A capitalized name

  • A single parent class (if applicable), with syntax extends Parent

  • Interface(s), with syntax implements firstInterface, subsequentInterface

  • Code block for the body of the class within curly braces {}

Number Systems

• Binary : “Base-two” numeral system. Conventionally represented with characters “0” and “1”. Used in computing as most basic analogue to on/off or unpowered/powered state.

• Decimal : “Base-ten” numeral system. Characters usually used are “0”, “1” through “9”. Extremely common for most types of measurement in the contemporary world.

• Hexadecimal : “Base-sixteen” numeral system (contemporary characters used are : “0”, “1” through “9”, and “A” through “F”).

  • Computing uses are common due to easier conversion from binary than to decimal notation.