Part Of The Object's State Main Method example essay topic

Computer Science Terms: Composite structure: the size of a typical software system implies that it must be broken down into manageable pieces of this Composition: the process of building a system using simpler parts or components Abstraction: the process of ignoring details irrelevant to the problem at hand and emphasizing essential ones. To abstract is to disregard certain differentiating details Data: the info the program deals with Functionality: what the program does with the data, the responsibility of the object to do Object: the most abstract description of a basic component of an object oriented system Values: a fundamental piece of info that can be manipulated by the program Types: a set of related values along with the operations that can be preformed with them Object: fundamental abstractions from which systems are built Classes: a set of objects having the same features and properties State of an object: the set of data maintained by an object at any given time Reference values: a value that denotes an object Data descriptions: properties of the object (name, date, etc) Associated value: a property an object has at any given time Variable: a portion of memory reserved to hold a single value Instance variables: a variable that is a permanent part of an object: memory space for the variable is allocated when the object is created Immutable: an object that's state cannot be changed Mutable: and object that's state can be changed An object is characterized by the features it offers 1. Query: a request for data 2. Command: a request to change state Float & Double: sets of real rational numbers (i.e. 170000 or 1.4 e 12) Char: set of values representing Unicode characters Boolean: true or false values Int value: contains a single integer String: and immutable object that contains a sequence of characters Identifier: a sequence of characters that can be used as a name in a Java program Literal: a sequence of characters that denotes a particular value in a Java program Comments: explanatory remarks that are included in a program for the benefit of a human reader and are ignored by the compiler Chapter 2: Features of an object: queries and commands A client queries and commands a server Specification (interface): definition of an object's features, as seen by its clients Implementation: provides the internals that actually make up the features Packages: groups of classes Public class: indicates that the objects of that class will be accessible throughout the system Public void: a command is a query that changes the state of the object but do not provide the client with a value Method: a language construct that defines and implements a query or command Constructor: a language construct used to create and initialize an object Static diagrams: diagrams showing classes Stub: dummy method or constructor New: used to invoke a constructor and create an object Interaction diagram: means of illustrating the order in which objects interact Statement: provides the action that the processor is to carry out Expression: a language construct that describes how to compute a particular value. Evaluation of this produces a value Reset: invoked command to change the count to zero increment Count: to increment the count by 1 Assignment: (variableName = expression - a statement that instructs the processor to computer a value and store it in a variable Parameters: elements of information that must be provided Method variable: a variable that is created when a method is invoked and de-allocated when the processor finished executing the method Numeric promotion: the conversion of and int to a double Operator precedence: / % + - Left associative: two expressions with equal precedence are evaluated from L to R Compilation unit: a file containing the definition of one or more classes of a package Import statement: placed at the beginning of a compilation unit (file), after a package statement, and apply to all classes defined in the compilation unit Assignment expression: consists of a variable (left hand side), assignment operator ( = ) and expression (right hand side) Increment expressions: il++ ++il Decrement expressions: il- - - -il Bitwise operators: allow the bit patterns of integral values to be manipulated Chapter 3: To design a class, determine an object's responsibilities and classify them as knowing responsibilities or doing responsibilities. Knowing responsibilities: knowing the properties of the entity the object is modeling, knowing about other objects with which it needs to cooperate Doing responsibilities: computing particular values, performing actions that modify its state, creating and initializing other objects, and controlling and coordinating the activities of other objects Local variable: a method variable created as part of a method execution, used to hold intermediate results needed during the computation.

LOCAL VARIABLE: . Defined inside a method. Exists only while the method is being executed. Must be initialized before being used; otherwise, a compiler error occurs.

Can be accessed only from the method. Is only meaningful during execution of the method. Contains some intermediate value needed only during execution of the method; its value is not part of the object's state INSTANCE VARIABLE: . Defined outside any method. Exists as long as the object exists. Initialized in a constructor.

Can be accessed from any method in the class. Has a meaningful value at any time during the life of the object, whether the object is actively doing something or not. Represents a property of the object; its value is part of the object's state Main method: the top-level method that initiates execution of a system Chapter 4: Post condition: a condition the implementer guarantees will hold when a method or constructor completes execution Invariant: a condition that always holds true Class invariant: an invariant regarding properties of class instances; that is, a condition that will always be true for all instances of a class If (condition) Statement And the if-then-else has the form If (condition) Statement 1 Else Statement 2 Chapter 5: Programming by contract:'s programming style in which the invocation of a method is viewed as a contract between client and server, with each having explicitly stated responsibilities When an object responds to a query, it does not change state. Commands result in a change of state. Chapter 6: Black box testing = functional testing Test design generally begins with an analysis of.

The functional specifications of the system. The ways in which the system will be used Test case is defined by: . A statement of case objectives. The data set for the case. The expected results Functional testing: testing to determine that the system as a whole meets the customer's specifications.

The system is treated as a "black box" whose behavior can be observed, but whose internal structure is unknown. white box testing = unit testing Unit testing: incremental testing of classes as they are implemented in order to ensure that they function properly. Testing can be "white box testing" where the tests are developed based on the unit's implementation, or "gray box testing" where tests are developed based solely on a method's specification.