Instance methods

Method We found that it's more appropriate to put these method inside the BankAccount class

An ideal class The BankAccount class is ideally suited to contain/store: Information about BankAccount ( instance variables) Operations on BankAccount variables ( method) Remember that program = data + algorithm

New notation to invoke a method

Terminology A class method Methods defined with the keyword static An instance method Methods defined without the keyword static

Shadowing a instance variable (1) When the method has: local/parameter variable = class/instance variable The class/instance variable can no longer accessible with the short hand notation in that scope

“This” (1) The Java compiler always assume that the type of the variable this is:

“This” (2) A variable name used inside a method: that matches the name of a local/parameter variable refers to the local/parameter variable Otherwise: it refers to a class variable or an instance variable

Shadowing a instance variable (2) Overcome the shadowing problem with instance variables: Use the full name to access the instance variable:

Object-oriented programming (OOP) An object is an entity with some state information and a set of well-defined operations It can be used to represent something in the real world It can be used to organize information used inside a computer program.

Implementing an object Represent the state information of the object accurately  with (instance) variables,  and Represent the operations on the object accurately  with (instance) methods

Copying an object (1) Both an object and an array are accessed through a reference variable

Copying an object (2)

Copying an object (3)

Copying an object (4)

Classes with private variables (1) Security/correctness considerations in computer programming

Classes with private variables (2) If there exist complex relationships between different  instance variables, we must maintain the relationship correctly Granting unrestricted access to the instance variables can result in incorrect changes and can give result in data inconsistency

Classes with private variables (3) public = there are no access restrictions to a variable or  method

Classes with private variables (4) private = access is restricted to the same class

Classes with private variables (5)