Object Oriented Programming MODULE 3-4 and 5

CLASS INSTANTIATION

“Creating an object”, Calling a class’s constructor creates an instance or object

FIELDS

MEMBER VARIABLES IN A CLASS

LOCAL VARIABLE

VARIABLES IN A METHOD OR BLOCK OF CODE

PARAMETERS

VARIABLES IN METHOD DECLARATIONS

Field Declaration composed of Three Components

1. ZERO OR MORE MODIFIERS, SUCH AS PUBLIC OR PRIVATE.

2. THE FIELD'S TYPE.

3. THE FIELD'S NAME.

ONE OF THE KEYS TO WORKING WITH OBJECTS

KNOWING HOW TO IDENTIFY THEM WHEN YOU LOOK AT SYSTEM-ANALYSIS DOCUMENTS OR DESIGN DOCUMENTS.

OBJECT IN JAVA

THE PHYSICAL AS WELL AS A LOGICAL ENTITY.

CLASS IN JAVA

A LOGICAL ENTITY ONLY.

Characteristics of object

1. State

2. Behavior

3. Indentity

State

Represent Data of an object.

Behavior

Represents behavior of objects such as deposits, withdraw, etc.

Identity

used internally bu the JVM to identify each object uniquely.

MEMBERS OF CLASS

1. Fields

2. Properties

3. Methods

4. Constructors

Fields

Holds values and must be accessed directly, Each must have a type

Properties

Provides a way to read, write, change a value held by field.

Methods

Code Block containing set of statements that will be executed (Instruction), May not return value of given type.

Constructors

Special method sets the initial values for properties in class.

TWO TYPES OF CLASS MEMBERS WHICH ARE MORE FREQUENTLY USED

1. Data Members (Variables)

2. Function Members (Methods)