Using Objects - Unit 2 (Video)

Vocabulary flashcards covering key terms from GridWorld and basic Java/object-oriented concepts from the notes.

GridWorld

A Java teaching environment with objects such as Actors, Bugs, Rocks, and Flowers on a grid to illustrate object‑oriented concepts.

CSP-GridWorld.jar

The Java Archive file required to run GridWorld programs.

Workspace

An IDE project organizer used for GridWorld projects.

Object

An entity with data (attributes) and operations (methods) that can manipulate that data.

Class

A blueprint for creating objects; defines data fields and methods.

Actor, Bug, Rock, Flower

GridWorld classes used to construct objects that inhabit the grid.

Parameter

Information a method needs in order to perform its task.

Argument

Actual data passed to a method when it is called.

Method

A sequence of instructions an object follows to perform a task.

Return Value

The information a method produces when it finishes.

Void

A return type indicating that no value is returned.

Constructor

A special method used to create a new object during instantiation.

Instantiation

Creating an object instance from a class using the new keyword.

Location

A grid coordinate class built with a row and a column (e.g., new Location(5, 7)).

Color constants

Color values from java.awt.Color (for example Color.GREEN) used to color objects.

Variable

A storage location in memory with a type, a name, and contents.

int

Primitive numeric type for integers.

double

Primitive numeric type for real numbers.

Declaration

Specifying a variable's type and name (for example, int age;).

Initialization

Assigning an initial value to a declared variable (for example, int age = 17;).

Assignment Operator

The equals sign used to assign a value to a variable ( = ).

Rules for Identifiers

Identifiers may contain letters, digits, underscore, and dollar signs; cannot start with a digit; no spaces; case-sensitive.

Java Naming Conventions (Classes)

Class names start with uppercase and use each word capitalized (PlanoWestWolf).

Java Naming Conventions (Variables/Methods)

Names start with a lowercase letter; subsequent words are capitalized (myDogSpot).

Java Naming Conventions (Constants)

Constants are all uppercase with underscores between words (NUMBER_ONE).

Strings

A sequence of characters; declared with String or new String(…).

String Concatenation

Joining strings with the + operator to form a new string.

String Length

The length() method returns the number of characters in a string.

Comments - Single-line

Single-line comments start with // and are ignored by the compiler.

Comments - Multi-line

Multi-line comments start with /* and end with * / and may span multiple lines.

Javadoc

Documentation comments that start with /** and may include @author, @param, @return tags.

Import Statements

Bring classes from other packages into scope; not needed for java.lang classes; examples include import info.gridworld.actor.Bug;.

Java API

The public interface for classes and methods in the Java library.

Object Reference

A variable that stores the memory address of an object; its type is the class name.

Calling a Method

Syntax: objectName.methodName(parameters); to invoke a method on an object.

Return Method vs Void Method

Return methods provide a value; void methods return no value.

Accessor vs Mutator

Accessor retrieves data without changing the object; mutator changes the object's data.

Overloaded Methods

Multiple methods with the same name but different parameter lists.

BugRunner

A GridWorld program that builds a world, adds objects, and runs the simulation.

world.add(location, actor)

Add an actor to a specific location in the grid; overloaded versions exist.

0-based Indexing

Grid row and column numbers start at 0; (0,0) is the upper-left corner.

Upper-left Corner (0,0)

The origin in a grid where row and column indexing begins at zero.