OOP test 2

Object-Oriented Programming (OOP)

A style of programming focused on the use of classes and class hierarchies

Polymorphism

(not on this exam)

Inheritance

Reuse and extension of fields and method implementations from another class

Encapsulation

Bundling data and code into a restricted container

Abstraction

Specifying a general interface while hiding implementation details (sometimes listed as a 4th fundamental concept of OOP, though I believe it's common to most paradigms)

Primitive type

A data type that can typically be handled directly by the underlying hardware

Enumerated type

A data type that includes a fixed set of constant values called enumerators

Class

A template encapsulating data and code that manipulates it

Interface

A reference type containing only method signatures, default methods, static methods, constants, and nested types

Instance

An encapsulated bundle of data and code (e.g., an instance of a program is a process; an instance of a class is an object)

Object

An instance of a class containing a set of encapsulated data and associated methods

Variable

A block of memory associated with a symbolic name that contains a primitive data value or the address of an object instance

Operator

A short string representing a mathematical, logical, or machine control action

Field

A class member variable (also called an "attribute" or "class variable")

Constructor

A special class member that creates and initializes an object from the class

Destructor

A special class member that cleans up when an object is deleted (not supported by Java)

Method

A function that manipulates data in a class (also called a "class function")

Getter

A method that returns the value of a private variable

Setter

A method that changes the value of a private variable

Multiple Inheritance

A subclass inheriting class members from two or more superclasses

Superclass

The class from which members are inherited

Subclass

The class inheriting members

Abstract Class

A class that cannot be instantiated

Abstract Method

A method declared with no implementation

Override

A subclass replacing its superclass’ implementation of a method

Declaration

A statement that introduces a name with an associated type into a scope

Definition

A declaration that also fully specifies the entity declared

Shadowing

A variable declared in a narrower scope than that of a variable of the same name declared in a broader scope

Namespace

A named scope

Package

A grouping of related types providing access protection and namespace management

Algorithm

A procedure for solving a specific problem, expressed as an ordered set of actions

Exception

An object created to represent an error or other unusual occurrence and then propagated via special mechanisms until caught by special handling code

Assertion

An expression that, if false, indicates a program error (in Java, via the assert keyword)

Invariant

Code for which specified assertions are guaranteed to be true (often, a class in which fields cannot change after instantiation)

Data Validation

Ensuring that a program operates on clean, correct and useful data

Validation Rules

Algorithmically enforceable constraints on the correctness, meaningfulness, and security of input data

Version Control

The task of keeping a system consisting of many versions well organized

Branch

A second distinct development path within the same organization and often within the same version control system

Fork

A second distinct and independent development path undertaken (often by a different organization) to create a unique product

Baseline

A reference point in a version control system, usually indicating completion and approval of a product release and sometimes used to support a fork

Unified Modeling Language (UML)

The standard visual modeling language used to describe, specify, design, and document the structure and behavior of object-oriented systems

Class Hierarchy

Defines the inheritance relationships between a set of classes

Class Library

A collection of classes designed to be used together efficiently

Relationship - Inheritance (generalization)

Solid line with a hollow triangle arrowhead pointing to the superclass. Maps to “extends” in Java.

implements UML

Dashed line with a hollow triangle arrowhead pointing to the interface. type of inheritance.

Relationship - Directed association

Association (solid line) with an arrow to show navigability (one class knows about the other).

Relationship - Multiplicity examples

1 exactly one; 0..1 optional; * many; 1..* one or more.

Relationship - Composition

Filled/black diamond at the whole end (e.g., Book ◆— Page). Parts have lifecycle bound to the whole.

Relationship - Dependency

dashed line, solid arrow. (java.util.ArrayList)

Relationship - Association class

A class (e.g., Checkout) attached to an association line that holds attributes/operations of the link.

External Type Dependency (java.util.__ usually)

Dashed line closed arrow to depednancy

When to use each relationship

Use inheritance for “is-a”; aggregation/composition for “has-a” whole–part; association for general links; dependency for occasional use/parameter types.

Relationship - Association

Plain solid line between classes showing a semantic connection; can have role names and multiplicities (e.g., 1..*).

Relationship - Aggregation

hollow diamond at bigger part. Parts can outlive the whole.