Algorithms that do things without precise specifications of how or even what they are doing.
A class that contains one or more abstract methods, and therefore can never be instantiated. Abstract classes are defined so that other classes can extend them and make them concrete by implementing the abstract methods.
A method that has no implementation.
Abstract Window Toolkit (AWT)
A collection of Java-supplied GUI components. These components provide that subset of functionality which is common to all native platforms.
A method which allows other classes to read (but not change) the values of the attributes. Accessor methods are also known as "getter methods." Accessor methods are public methods that merely return the value of the attribute.
See also getter method.
Access protection allows programmers to restrict access to members of the class.
Application Programming Interface. The API specifies the method used by a programmer when writing an application to access the behavior and state of classes and objects.
A program written in Java to run within a Java-enabled Web browser.
Unlike an applet, a Java application does not require a Web browser to function. Applications are often referred to as "stand-alone."
A data item specified in a method call. An argument can be a literal value, a variable, or an expression.
A collection of data items, all of the same type, in which the position of each item is uniquely designated by
a discrete type.
American Standard Code for Information Interchange. A standard assignment of 7-bit numeric codes to
The attributes of the class are the values that define the state of the class. Attributes are also referred to
as fields or variables.
A reusable software component. Beans can be combined to create an application.
Refers to an expression or variable that can have only a true or false value. Java provides the boolean type and the literal values true and false.
A CASE tool creates design specifications for programmers and software designers. CASE stands for
"Computer Assisted Software Engineering." A good CASE tool not only draws diagrams; it also can convert those diagrams to compilable source code in any of variety of languages.
children or child
A term occasionally substituted for subclass.
In Java, a type that defines the implementation of a particular kind of object. A class definition defines
instance and class variables and methods, as well as specifying the interfaces the class implements and the immediate superclass of
Any object or class outside the pattern; generally one that only knows about the public interface the pattern
and its classes present, rather than about its private implementation.
In a program, the explanatory text that is ignored by the compiler. In Java programs, comments are delimited
using // or /*...*/.
A program to translate source code into code to be executed by a computer. The Java compiler translates Java
source code into Java bytecode.
Creating objects with other objects as members. Composition should be used when a "has-a"
A pseudo-method that creates an object.
Describes how data is arranged in the structure.
This pattern is one where a given object provides an interface to a set of operations. However, the actual work
for those operations is performed by one or more other objects.
Refers to a class or method that is no longer important, and will probably cease to exist in the future.
Early binding assumes that everything is known at compile time. It is always obvious which method will be
invoked in which class at which point in the flow of a program. Early binding is slightly faster than late binding and is used
exclusively by procedural languages like C and FORTRAN.
The localization of knowledge within a module. Because objects encapsulate data and implementation, the user of
an object can view the object as a black box that provides services. Instance variables and methods can be added, deleted, or
changed, but as long as the services provided by the object remain the same, code that uses the object can continue to use it
without being rewritten. See also instance variable, instance method.
An event during program execution that prevents the program from continuing normally; generally, an
Another term for "is a subclass of."
Something other than the object itself keeps track of the state of the object.
The fields of the class are the values that define the state of the class. Fields are also referred to as
attributes or variables.
Providing friendly access to the fields of a class exposes the normally private implementation of a class to
certain closely related classes that must access the class's fields frequently. Friendly members of a class are identified in a
class diagram by underlining them.
A method that allows other classes to read (but not change) the values of the attributes. Getter methods are
also known as accessor methods. Getter methods are public methods that merely return the value to the attribute.
Graphical User Interface. Refers to the techniques involved in using graphics, along with a keyboard and a
mouse, to provide an easy-to-use interface.
A classification of relationships in which each item except the top one is a specialized form of the item above
it. Each item can have one or more items below it in the hierarchy.
The implementation of a pattern is a set of code that uses the pattern. It shows the details and tricks that
are needed to make it work.
Implementation inheritance allows a superclass and a subclass to share identical code for the same method. This
sort of inheritance encourages code reuse.
The concept of classes automatically containing the variables and methods defined in their supertypes. See also
An object of a particular class.
The public members of a class.
With respect to software, the term interoperability is used to describe the capability of different programs to
exchange data via a common set of business procedures, and to read and write the same file formats and use the same
An object-oriented programming language developed by Sun Microsystems.
A "write-once, run-anywhere" programming language.
A portable, platform-independent reusable component model.
Java Development Kit (JDK)
A software development environment for writing applets and application in Java.
Late binding allows design decisions to be deferred until runtime. Late binding is generally more flexible, and
is used exclusively by Smalltalk and Java.
The basic representation of any integer, floating point, or character value. For example, 3.0 is a
single-precision floating point literal, and "a" is a character literal.
A field or method of a class. Unless specified otherwise, a member is not static.
The operations of a class are stored as methods. A method, similar to a function in a procedural language like
C, represents an action an object takes, or an operation the class performs.
Method overloading permits two methods (or constructors) to have the same name as each other, provided they can
be distinguished by their argument lists.
Multiple inheritance allows a single subclass to extend more than one superclass.
Describes a program that is designed to have parts of its code execute concurrently.
Mutator methods allow nonsibling objects to change the state of an object. Typically, a mutator method is a
public method. Mutator methods return as void and generally take a single argument of the same type they are setting. Mutator
methods are also known as "setter methods." See also setter method.
A constructor that does not take arguments. They are sometimes referred to as "no-initializer
The principal building block of object-oriented programs. Each object is a programming unit consisting of data
Other objects are stored as pointers or references inside the object that provides the interface to clients.
Object composition is a powerful yet often overlooked tool in the OOP programmer's toolbox. Structural patterns show you how to
take advantage of it.
A software design method that models the characteristics of abstract or real objects using classes and
A programming methodology that uses distinct units of functionality, with each unit called an object.
The operations of a class define what an object does.
The operations compartment is the box at the bottom of the class diagram that contains method names.
Object Request Broker
An Object Request Broker (ORB) is the programming that acts as a mediator between a client request for a
service from a distributed object or component and the completion of that request.
The ORB is the middleware that establishes the client-server relationships between objects.
An overloaded method has the same name but a different argument list as another method in the same class.
Using one identifier to refer to multiple items in the same scope.
Replacing a method that would otherwise be inherited from a superclass with a new method defined in the
subclass is called overriding the method.
A term occasionally substituted for superclass.
By declaring that a member of a class is protected, you indicate that subclasses are allowed to access the
member, though other nondescendant classes are not. Protected members are preceded by a "#" in the class diagram.
Attributes with an accessor method but no mutator method can be gotten but not set. These are called read-only
The responsibilities of a class are defined as things the class knows, or the attributes of the class, plus the
things the class does, or the operations of the class.
Methods can return information to whoever called them. This information is commonly called the method's
return value, and like a method argument it has a type. Unlike a method argument, the return value does not have a name.
The vice versa direction-source code to diagrams-is commonly referred to as reverse engineering.
A characteristic of an identifier that determines where the identifier can be used. Most identifiers in Java
have either class or local scope. Instance and class variables and methods have class scope; they can be used outside the class and
its subclasses only by prefixing them with an instance of the class or (for class variables and methods) with the class name. All
other variables are declared within methods and have local scope; they can be used only within the enclosing block.
A server is a program that awaits and fulfills requests from client programs in the same or other computers.
Setter methods allow nonsibling objects to change the state of an object. Typically, a setter method is a
public method. Setter methods return as void and generally take a single argument of the same type they are setting. Setter methods
are also known as "mutator methods." See also mutator method.
Objects of the same class are called siblings. Siblings are allowed to access the private elements of other
The signature of a method is its list of argument types.
Another name for "class variable."
A member that is shared by all variables of that class and is stored in only one place. Static members are
identified by underlining them in a class diagram.
Another name for "class method."
A class that is derived from a particular class, perhaps with one or more classes in between.
A class from which a particular class is derived, perhaps with one or more classes in between.
The variables of the class are the values that define the state of the class. Variables are also referred to as "attributes" or "fields."
A method that does not return a value is considered void.
Attributes with a mutator method but no accessor method can be set but not gotten. These are called write-only