Thursday, May 8, 2008

Object oriented programming (OOP) explained with an example

Create a class that keeps track of a bank account balance. Then write a program to use this class.


Steps involved:


· Run the class builder utility (SE24).

· Create a class called ZACCOUNTxx, where xx is the last two digits of your logon ID.

· Declare a PRIVATE attribute BALANCE of type DMBTR to store the account balance.



Create the following PUBLIC methods:

o SET_BALANCE (Sets the balance to a new value)

§ IMPORTING NEW_BALANCE TYPE DMBTR


o DEPOSIT (Adds a deposit amount to the balance and returns the new balance)

§ IMPORTING AMOUNT TYPE DMBTR

§ RETURNING NEW_BALANCE TYPE DMBTR


o WITHDRAW (Subtracts a deposit amount from the balance and returns the new balance.)

§ IMPORTING AMOUNT TYPE DMBTR

§ RETURNING NEW_BALANCE TYPE DMBTR

§ EXCEPTIONS INSUFFICIENT_FUNDS


· Activate all elements of your class.


· Write a program called Z_USE_ACCOUNT_xx, where xx is the last two digits of your logon ID.


This program should do the following:


o Instantiate an instance of the Account class.

o Set the account balance to some initial value.

o Make several deposits and withdrawals, printing the new balance each time. Do not allow the balance to become less than zero. (Use the exception to detect this.)

· Test and debug your program.


"Extra Credit": If you have extra time, try any of the following:


· Replace the SET_BALANCE method with a constructor. Pass the opening balance when you instantiate the account object.

· Create a static attribute and methods to set and get the name of the bank that holds the accounts.

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