Comp science - Object Oriented

(int)(x+0.5)

Rounds the value of a double to the nearest whole number

Primitive Type

Primitive types are the basic, simple data types that are inherent to Java (int, double, char, and boolean)

Abstract Class

A class, usually at the top of a Class Hierarchy, that cannot be instantiated, because not all of its methods are defined.

Abstract method

Methods added to the abstract classes, that is not defined. the word (abstract) must come before the method’s return type.

Access Specifier

Determines who has access to using the method when writing classes and objects.

Accessor Method

A method that enables user to obtain information about an object’s instance and static variables. Usually refered as getter method

Algorithm

An algorithm is a set of steps or rules to follow to solve a particular problem.

Assigning to a variable

Updating the variable values. The variable is already declared. Setter methods do this

Attributes of on object

Object characteristics. Also called Instance variables

Behavior

The actions that can be completed by an abject or a class. Also called Class Methods/ Instance methods.

Boolean

A Java type that can either be true or false. It is also a Primitive.

Break

Breaks out of a while loop and executes statements that immediately follow while loop

Calling Method

objectName.method() → Calling a method

Char

is a java type that represents a single character

Casting

Turning something of one type into anther type

Class

Classes are template through which objects are created. It is the formal blueprint for creating objects. Every program starts with a class

Class Hierarchy

Class hierarchy refers to the arrangement of classes and how they relate to each other.

Client

When someone creates a class (like String, or Randomizer), and you are using the functionality of that Class in your program, your program is a client of the class. You are using the class as a client.

Compile Time Error

An error in the actual Jaava code. The code will not compile into an excutable program.

Concatenation

The process of adding two string valuables together.

Contractor

Special method of a class that constracts a new object. Sets the initial values.

Declare Variable

Defining variable for the first time

Define Method

Defining a method means to teach the computer a new command and explain what it should do when receiving that command.

Double

Jave type that represents

Encapsulation

The process of hiding the implementation details of a class from the user

Exception

Thrown by java when a runtime error is encountered.

For Loop

Repeats code a fixed number of times

Getter method

An instance method that allows the client to **get** the value of an instance variable on an object.

\

If Statements

if (boolean expression) { //execute statements if condition is true }

Immutable

Unable to be changed or manipulated. String are immutable.

Infinite loop

Occurs when the expression in a while loop never evaluates to false. The program continues to run infinitely.

Inheritance

When a subclass extends a superclass, the subclass inherits all of the static methods, static variables, and public instance methods of the superclass. This is called inheritance.

Initialize a Variable

Initializing a variable is giving it an initial value, or a starting value.

Instance

\
\
Create an instance of a class object.

\

Instance Methods

An instance method is a method that defines the behavior of an object. It defines an action that the object can perform.

Instance Variable

Used to store the state, or data of the object instances.

Int

`int` is a Java type that represents an integer (a whole number)

Local Variable

A variable that is defined in a method or constructor. It only exist in the context of the method that it belongs to.

Loop-and-a-half

A loop, most often set with `while(true)`, that has a `break` statement in the loop body.

Method

Procedures that allow us to control and define the behavior of an object.

Method Overloading

Classes can have multiple methods with the same name, as long as the parameters to those methods are different. Doing this is called "overloading" a method.

Method Overriding

If a subclass defines a new method body for a method defined in the superclass, then the subclass has **overridden** the method of the superclass.

Mutator Method

A method that enables user to change the value of an object’s instance and static variables.

OR

Methods used to change or manipulate instance variable or object data. Also referred to as setter methods.

\

New

Necessary keyword for instantiating a new class object.

Object

An object is a variable of a data type that is user defined. Every object has a state and a behavior.

Object Oriented Programming

\
\
Programming model that focuses on **objects** and the data and actions associated with the objects.

\

Parameter

A variable passed into a method from outside the method.

Polymorphism

An object can take on different forms depending on its implementation. Java can call the correct method even when an object is disguised as a more generic reference type

Primitive Types

Primitive types are the basic, simple data types that are inherent to Java (int, double, char, and boolean)

Private

Restricts access to data and methods to the declaring class.

Public

Allows access to data and methods from classes outside the declaring class.

Return

Keyword used in methods to return a value back to the initial program that called the method.

Return Type

The `return` statement exits a method and returns a value.

Return Value

The value returned from a method

Runtime Error

An error that happens while the program is running. Even if the code is written with the proper syntax, there are things that can go wrong while the program is running.

Scope

Defines which part of the program a variable can be accessed from.

Sentinel

\
A constant that has the specific purpose of being the value that breaks out of a loop.

\

Setter method

An instance method that allows the client to **set** the value of an instance variable on an object.

Shadowing

If two variables within the same scope have the same name, the variable with the more specific scope will be called.

State

The state of an object is all of the object's associated data. It is the *state* that the object is in. The data that is associated with an object or class.

Static method

A method called on the Class, rather than on a specific object of the Class.

Static Variable

A variable or attribute of a class that is shared between **all** instance of a class. Each instance **does not** get their own copy.

String

String is a Java type that represents a string of characters (text)

Subclass

A child class that inherits attributes and behaviors from a superclass (parent).

Super

The `super` keyword lets us reference the superclass when writing code inside of a subclass.

Superclass

\
\
A parent class that contains common attributes and behaviors used by subclasses (children).

\

this

The `this` keyword is a reference to the current object (the current instance).

toString

A specific accessor method that returns a String value with information about an object’s instance values. This overrides the object’s inherit toString method when an object is printed using System.out.print or System.out.println

Variable

A symbol or container that holds a value.