AP Computer Science A: Object-Oriented Programming Guided Notes

Abstraction

Simplifying something and reducing its complexity by focusing on its main idea.

Procedural Abstraction

When programmers reuse methods/functions/procedures without knowing every single detail on how they work.

Data Abstraction

Simplifying how data is represented in a program.

Class Methods

Methods associated with classes, not instances.

Instance Methods

Created from a class's instance; requires creating an object, referencing its name with dot notation, and calling the method.

Scope

How accessible something is within a program.

Procedural Programming

Programming centered around procedures, breaking programs down into methods.

Object-Oriented Programming

Programs designed to model real-world or virtual things that can communicate and interact with each other. A class serves as a blueprint defining an object's attributes and behaviors.

Attributes

Like a noun; attributes define the "what" of something, holding the data for an object.

Behaviors

Like a verb; behaviors depict the "how" and describe the actions that an object carries out.

Relationship of Attributes to an Object

A "has a" relationship, indicating attributes reveal the properties of an object or its features.

Purpose of the Reserved Word "new"

Creates a new object of the respective class using its constructor.

Default Constructor

A constructor that does not have any parameters.

UML (Unified Modeling Language)

A standard for visually representing a program's design and documentation through diagrams.

Class Diagram

Depicts a class's key properties and its relationships with other classes.

Instance Variables

Another term for attributes; variables referenced by specific objects that hold data and belong to the object.

Object's State

The current value of an object's instance variables.

Overloading

Using the same name for different methods/constructors as long as their parameter lists are different.

Encapsulation

Keeping data private.

Accessor Method

A method that can access private instance variables but cannot change them; also known as a getter.

Mutator Method

A method capable of changing a private instance variable's value; also known as a setter or modifier.

Client Class

A class that uses other classes (e.g., PlanetTester is a client class for Planet).

Implementation Class

A class that defines objects (e.g., Planet is an implementation class).

Key to Object-Oriented Programming

The ability to construct multiple objects.

Method for Comparing Objects

equals() method.

Passing Reference Types as Arguments

Passing a reference type tells a method the address of an object; changes to the original object also affect the reference type.

Java Behavior with Primitive Data Types

Java makes a copy of a value to initialize the parameter; changes to the original value do not affect the parameter.

Scope of a Variable

The accessibility of a variable within a piece of code.

this Keyword

A special variable that references the current object; useful for distinguishing between two variables with the same name.

Static Methods

Can be executed without the prior existence of an object.

Non-Static Methods

Can only be called if an object exists.

Purpose of the Final Keyword

Ensures that a variable remains constant and cannot be changed.