CSCI 114 Programming Fundamentals II Lab 5 Inheritance complete solutions correct answers key

CSCI 114 Programming Fundamentals II Lab 5 Inheritance complete solutions correct answers key

Purpose

Purpose is to practice using regular inheritance.

The Checking superclass

First design, code and test a class called Checking. This will be your superclass.

Use exactly and only these instance variables:

private String accountID -an identifying account number e.g. “123”

private int balance -balance of the account in pennies, to avoid floating

point round-off errors e.g. 100 means $1.00

private int numDeposits -number of deposits made this month

private int numWithdrawals -number of withdrawals made this month

private double annualRate -annual interest rate e.g. 0.15 means 15% per

annum

private int serviceCharge -maintain the total monthly service charges incurred

here, in pennies

Checking will have the following methods. Be careful to implement the steps of each

method in exactly the order given below:

constructor

-has parameters for the account ID, starting balance (in dollars) and annual interest rate

-must initialize all instance variables

-use the following to convert the dollar starting balance parameter bal to cents, avoiding

round-off error:

balance = (int) Math.round(bal * 100.0);

appropriate get and set methods

-you have to decide during design what get and set methods are required

deposit()

-has a parameter for the deposit amount in dollars

-make the necessary conversion then add the amount to the balance

-increment the number of deposits

-add a deposit fee of 10 cents (in pennies) to the monthly service charge

© Anthony W. Smith, 2016

CSCI 114 Programming Fundamentals II

Lab 5 Inheritance

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-note that the deposit fee is NOT deducted from balance at the time of the deposit

transaction

-(use static final constants for all the fee amounts)

withdraw()

-has a parameter for the withdrawal amount in dollars

-make the necessary conversion then subtract the amount from the balance

-increment the number of withdrawals

-add a withdrawal fee (in pennies) to the monthly service charge:

-the first 2 withdrawals cost 25 cents each

-withdrawals after the first 2 cost 75 cents each

depositInterest()

-update the balance by calculating the monthly interest earned on the account, then add

this interest to the balance. In pseudocode:

monthly interest rate = annual interest rate / 12.0

monthly interest = balance * monthly interest rate

balance = balance + monthly interest

-(use Math.round() where necessary to prevent rounding errors)

printMonthEnd()

-run at the end of the month to first add interest, then deduct monthly service charges,

than summarize the account. In pseudocode (implement these actions in exactly this

order):

call the depositInterest() method

add a monthly fee of $1.00 to the monthly service charge

decrease the balance by the total monthly service charge

output the account ID, resulting balance, number of deposits and withdrawals and the

monthly service charge (use printf() to output monetary amounts in dollars, with 2

decimal places)

set the number of deposits and withdrawals and monthly service charge to zero

-an example of the printMonthEnd() output format:

Account ID 123

Balance is: $751.88

1 deposits, 3 withdrawals

Monthly service charge was: $2.35

© Anthony W. Smith, 2016

CSCI 114 Programming Fundamentals II

Lab 5 Inheritance

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toString()

-return a String that represents the Checking object, must be in standardized formatting

e.g.

Checking[accountID=123, balance=74800, numDeposits=1, numWithdrawals=3,

annualRate=0.1, serviceCharge=135]

The MoneyMarket subclass

Next design, code and test a MoneyMarket subclass that inherits from Checking.

MoneyMarket instance variable:

active a boolean variable that maintains the status of the account. Status is

defined as active if the balance is greater than a minimum balance of

$500.00, otherwise is not active. Account status must be updated

every time the account balance is changed. Withdrawals are not

allowed if the account is not active, until deposits make the account

active again

MoneyMarket will have the following methods Be careful to implement the steps of

each method in exactly the order given below:

constructor

-has parameters for account ID, the starting balance (in dollars) and annual interest rate

-use the superclass constructor to set these

-then set whether the account is active or not active

withdraw()

-output a message in the following format if the account is not active, and done:

MoneyMarket 456: Withdrawal not allowed

-otherwise call Checking withdraw() (use super to do this), then must update the status

of the account

deposit()

-call Checking deposit() (use super to do this), then must update the status of the

account

printMonthEnd()

-run at the end of the month to add interest, deduct monthly service charges and

summarize the account. In pseudocode (implement these actions in exactly this order):

© Anthony W. Smith, 2016

CSCI 114 Programming Fundamentals II

Lab 5 Inheritance

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add a minimum balance fee of $5.00 to the monthly service fee if the account is not

active

call Checking monthEnd() (use super to do this)

update status of the account

output the status of the account e.g.

"Money market account is: active" or

"Money market account is: inactive"

-an example of the printMonthEnd() output format for the MoneyMarket class:

Account ID 456

Balance is: $296.15

1 deposits, 1 withdrawals

Monthly service charge was: $6.35

Money market account is: inactive

toString()

-return a String that represents the MoneyMarket object, must be in standardized

formatting e.g.

MoneyMarket[accountID=456, balance=30000, numDeposits=1,

numWithdrawals=1, annualRate=0.1, serviceCharge=35][active=false]

The Tester class

The Tester class tests your new Checking and MoneyMarket classes. Source code for

Tester is given below, and can be downloaded from Blackboard, Course Documents,

Week 12, Example programs.

import java.util.ArrayList;

/**

* Driver for Lab 5 Inheritance

*

* @author Anthony W. Smith

* @version 5/31/2028

*/

public class Tester

{

public static void main(String arg[])

{

// create some accounts

// $100.00, 10.0% annual interest

Checking check = new Checking("123", 100.0, 0.1);

// $1000.00, 10.0% annual interest

MoneyMarket money = new MoneyMarket("456", 1000.0, 0.1);

© Anthony W. Smith, 2016

CSCI 114 Programming Fundamentals II

Lab 5 Inheritance

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ArrayList accounts = new ArrayList<>();

accounts.add(check);

accounts.add(money);

// do some transactions

System.out.println("Transactions");

// on Checking object

check.deposit(750.0);

check.withdraw(12.0);

check.withdraw(34.0);

check.withdraw(56.0);

// on MoneyMarket object

money.withdraw(750.0);

money.withdraw(100.0);

money.deposit(50.0);

// print accounts

System.out.println("\nPrint accounts");

for (Checking c : accounts)

System.out.println(c.toString());

// print month end report

System.out.println("\nMonth end report");

for (Checking c : accounts) {

c.printMonthEnd();

System.out.println();

}

}

}

Hints

 first, take a calculator and work carefully through Tester line by line, writing down

on a piece of paper the values of the instance variables that should be produced...

 this makes sure you understand what every method does, and gives you the expected

output you need to test your program

 now design your new Checking and MoneyMarket classes on a piece of paper

 use inheritance – a MoneyMarket account is-a Checking account, with an account

status added

 design algorithms, think about parameters and return values

 then use BlueJ as usual to code and test each method in turn. Comment out in Tester

the methods you have not yet implemented

© Anthony W. Smith, 2016

CSCI 114 Programming Fundamentals II

Lab 5 Inheritance

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Required

 Tester in your final submission must not be changed in any way

 every method must have a clear, meaningful Javadoc comment

 each toString() is required to use standardized formatting

 automatically and routinely use all the other components of simplicity and clarity, as

listed in Blackboard, Course Information, “How labs are graded”

 when you have thoroughly tested your program and are certain it is correct, save your

output into the output.txt file

Lab 5 submission