Object oriented programming vocab

(int)(x + 0.5)

Rounds the value of a double to the nearest whole number.

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

A method, written in an Abstract Class, that is not defined. The word abstract must come right before the method's return type. It is up to the subclass to fill in the definition for the abstract method.

Accessor Method

A method that enables the user to obtain information about an object’s instance and static variables. Also referred to as getter methods

Getter Method

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

Assigning to a variable (setter methods)

Assigning to a variable is updating the variable's value

attributes of an object (instance variables)

An object’s characteristics.

Behavior (methods)

The actions that can be completed by an object or class.The behavior of an object is what the object is able to do. It is the actions that can be performed by the object.

Boolean

boolean is a Java type that can either be true or false. It is primitive. 

break

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

Calling a method

Calling a method actually gives the command, so the computer will run the code for that method. objectName.method()

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Casting

Casting is turning something of one type into another type 

Compile Time Error (syntax error)

An error in the actual Java code. The code will not **compile** into an executable program, because there are errors in the text of the code.

Client

When someone else 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.

Class Hierarchy

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

Class

A class is a template, or a blueprint, from which Java objects are created. All Java programs start with a class.

char

char is a Java type that represents a single character (a single letter). It is a primitive 

Define a method

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

Declare a Variable

Declaring a variable is defining it for the first time.

Constructor

A constructor is a special method of a Class that constructs a new object (a new instance) of the Class and sets the initial values for the instance variables.

Concatenation

The process of adding two String values together. This creates a new String object. Primitives can be concatenated with String objects.

double

double is a Java type that represents a real number with decimal values. It is primitive. 

Encapsulation

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

Exception

An exception is thrown by Java when a **runtime error** is encountered. The exception provides information about what kind of error occurred.

For Loop

A for loop lets us repeat code a fixed number of times.

Immutable

Unable to be changed or manipulated. String are immutable.

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.

Instance Variable

A variable defined in a Class, for which each object of the class has its own copy

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 exists in the context of the method that it belongs to

Instance Method

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

Instance

Instance is what you call a specific object constructed from a class. Instance and object generally refer to the same thing. An object is a specific instance of a class

new

Necessary keyword for instantiating a new class object.

Loop-and-a-half

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

Method

A method is a way to teach the computer a new command

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. Methods can have multiple signatures. Java will use the correct signature based on the actual parameters used in a program.

Method overloading

Methods can have multiple signatures. Java will use the correct signature based on the actual parameters used in a program. 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.

Mutator Methods

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

Object Oriented Programming

The use of object and class types in programming.

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

Object

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

Private

Restricts access to data and methods to the declaring class.

Primitive Type

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

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. Polymorphism is the capability of a method to do different things depending on which object it is acting upon.

Parameters

Pieces of information you can give to functions when you define them. When the function is called the arguments are the data you pass into the function's parameters. Parameter is the variable in the declaration of the function. Argument is the actual value of this variable that gets passed to the function.

Return value

The value returned from a method.

Return type

A method's return type is the type of value returned from that method.

return

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

public

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

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.

Static method

A method called on the Class, rather than on a specific object of the Class.Static methods are the methods in Java that can be called without creating an object of class. Static methods are called using the dot operator along with the class name unless they are defined in the enclosing class.

Shadowing

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

State(instance variable)

The data that is associated with an object or class