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29 Cards in this Set

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Class
A programming unit that captures abstraction. We talk about the state or attributes (nouns that describe) of an object (the abstraction) and its behavior, the services or tasks it can perform (think of verbs), encapsulated in its methods.
Class Heading
The line of code that names the class and defines its relationship, if any, or another class or to interfaces.
Instance
An object of a specified class type. More than one object may be instantiated (created) at any given time.
Instance Variable
A variable that must be referenced through an instance of the class. These variables define the attributes of a particular instance and are private.
Field
Another name for instance variable.
Constant
A value that cannot be changed during program execution. The purpose of constants is to make programs more readable and to make it easier for the programmer to change a value that is used repeatedly through out the program for example, a tax rate, specified with the keyword final.
Class Variable
A variable that is shared by all instances of a class. The keyword static is used to define a class variable. It may be referenced using the class name, but, more importantly, if changed by one instance of the class, its value is changed for all instances.
Method
A task that an instance of a class can perform.
Method Signature
The method heading. This defines the method as public, private, or protected; specifies its return type; lists the method name; and specifies its parameters. The name is not important to the definition of signature but, if the method is well named, it well you what the method does.
Method Overloading
The idea that two methods may have the same name as long as they have different signatures. (A consequence of this is that the system can distinguish which method is to be used based upon the parameter sequence.)
Visibility Modifier
Defines how a construct can be accessed; for our purpose, usually applied to a variable or a method.
Public
Visible to all users of the class.
Private
Invisible to users of the class; visible only within the class itself.
Protected
(not covered on the AP exam, except in the context of the case study): Visible only to the class and subclass of the class.
Constructor Method
A method whose task is to instantiate (create or build) an object, accomplished by initialing the instance variable. You can pick out a constructor easily because its name must be the same name as the class name and there is no return type. There may be more that one constructor (this is called overloading), distinguished by a difference in number or types of arguments in the parameter list.
Default
A value that will be used instead of a programmer-specified parameter, often for a constructor. A constructor that uses no parameters at all, instead substituting predefined values, is often called a default constructor.
Accessor Method
A method that returns the value stored in an instance variable. This is the way a client program or another class gains access to information about the state of an object.
Modifier or Mutator Method
A method that changes the state of an object. These methods are usually, but not always, void, meaning they do not return a value.
Helper Method
Private method used within a class. A helper method may avoid repetition of code or may aid in breaking down a complicated method into simpler tasks.
Parameter
Required information passed to a method so that it may accomplish its task.
Formal Parameters
The parameters listed in a method signature. For example, in the method signature:
public int sumUp(int first, int last)
the formal parameters are first and last.
None
Actual Parameters
The values supplied by the client in the parameter list of a method call. In the method call:
int sum = nums.sumUp(start, end)
the actual parameters are stare and end.
None
Explicit Parameters
Information passed in the parameter list:
int sum = nums.sumUp(start, end)
the explicit parameters are start and end.
None
Implicit Parameters
The object upon which a method id called:
int sum = nums.sumUp(start, end)
the implicit parameter is nums.
None
Local Variable
Variable declared within a method.
Client
User of a class; may be the main method or the method of another class
Main method
The method in an application where execution begins.
Implementation
Code that defines a construct.
This
A reserved word for the implicit parameter; used within a class when a referenced to the implicit parameter is needed.