The local bank offers various types of accounts, some of which pay interest dividends and others that do not. For example, this bank offers
- savings accounts, which offer a flat, simple rate of interest;
- certificates of deposit (CDs) that pay interest on the balance above some minimum;
- checking accounts, some of which pay interest just like a savings account, but only if set up that way.
You will implement a bank simulation that will track various types of accounts and generate a report of the interest paid (or $0.00 if none) and the current balance of each account. All accounts must appear on the report. The report will consist of the following information for each account: owner name, interest paid, and current balance. At the end of the report, display the totals of the last two amounts across all balances.
With your team members, answer the following questions and submit to your instructor before you leave the problem solving session today:
- Think about the account types: Savings, CD, and Checking with or without interest. What attributes and operations are similar for all account types?
- What attributes and operations are different or unique for each account type? Draw a class diagram for each class.
- On your class diagrams, show the relationships between the classes. To keep things simple, we'll assume that the bank only needs to track the information generated in the report: the account owner's name, the interest paid, and the current balance.
- In the simulation you will implement, each account will only have its interest computed once, but conceivably these computations could be done over and over as time went by. How will you implement your classes' methods?
Now that you have had some experience designing your own classes, we want you to implement a solution using our design. This will involve implementing all three account types (a class for each), and the simulation program. Since we want to build the is_a relationship between the account types, we'll use a super class -- in this case an abstract class.
As you saw from the problem solving session, all account types have a lot in common. One commonality is that all accounts must report the amount of interest paid. We will designate that method to be abstract because we don't know how each account will calcualte the interest - we'll leave that to the implementing class to specify.
In addition to the BankAccount classes, you will also write a test
program, TestBankAccount.java that will test your implementation (see
below).
Take a moment to familiarize yourself with the program design by reviewing the javadocs. The project contains five different classes. You are to write all five classes, based on their javadoc specifications.
- BankAccount - An abstract class that represents an account.
- CheckingAccount,
SavingsAccount,
CDAccount - Concrete subclasses of
BankAccountthat each implement their own uniquecalcInterestbehavior. - The Test Program - The class which tests all classes and generates a sample interest report.
These classes and their relationships can be visualized in the following UML diagram. Notice that we are showing you the recommended state for each of the classes. You are free to represent the state of your classes however you choose, but do not duplicate state unnecessarily!
For this lab, we are providing only the javadocs. You will implement a solution for all the classes, including:
-
BankAccount.javathe abstract class. -
The three subclasses of BankAccount:
CDAcount.javaThe Certificate of Deposit class.CheckingAccount.javaThe Checking Account class.SavingsAcount.javaThe Savings Account class. -
You will also write a test class,
TestBankAccount.java. Your test class must create ONE data structure (you decide - an array, LinkedList, ArrayList, ...), fill it with 5-10 different accounts, and generate the interest report.Note that each class contains a
toString()method. You may find this method helpful in your testing, but you should use theprintStatement()method when generating your report.For tips on how to format your output, check this link: How To Format Data.
A sample run of the program is here (incorrect values). This is an example of the correct output.