Exercises 11.2
1. No
2. Yes
Ð subclass: Squares
3. No
4. No
5. No
6. Yes Ð subclass: Professors
7. Yes Ð subclass: Employees
8. Yes Ð subclass: Computers
9. No
10. No
11. No
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
(a)
/**
License.java provides a class to model licenses in general.
*/
import
ann.easyio.*;
public
class License extends Object
{
/** License constructor
*
Receive: int number,
String name, int age
*
Postcondition: A License object is constructed with myName == name
*
&& myAge &&
age && myIdNumber == number.
*/
public License(String name, int age,
int number)
{
myName = name;
myAge = age;
myIdNumber = number;
}
//--- Accessors ---
public String getName() { return myName; }
public int getAge() { return myAge;
}
public int getIdNumber() { return
myIdNumber; }
//--- Output method ---
/** toString converter
* Return: a
String representation of a License
*/
public String toString()
{
return getName()
+
"\n" + getAge() + " years old"
+
"\nID: " + getIdNumber();
}
//--- Attribute variables ---
private String myName;
private int myAge;
private int myIdNumber;
}
(b)
/**
HuntingLicense.java provides a class to model hunting licenses.
*/
import
ann.easyio.*;
public
class HuntingLicense extends License
{
/** HuntingLicense constructor
*
Receive: int number, String name, int
age, String prey
*
Postcondition: A HuntingLicense object is constructed with
*
myName == name && myAge
&& age
*
&& myIdNumber == number && myPrey == prey.
*/
public HuntingLicense(String name, int
age, int number, String prey)
{
super(name, age, number);
myPrey = prey;
}
//--- Accessor ---
public String getPrey() { return myPrey; }
//--- Output method ---
/** toString converter
*
Return: a String representation of a License
*/
public String toString()
{
return super.toString() +
"\nPrey: " + getPrey();
}
//--- Attribute variables ---
private String myPrey;
}
24.
/**
DeerHuntingLicense.java provides a class to model hunting deer licenses.
*/
import ann.easyio.*;
public class
DeerHuntingLicense extends HuntingLicense
{
/** DeerHuntingLicense constructor
*
Receive: int number, String name, int
age, String prey,
*
boolean, doePermit
*
Postcondition: A HuntingLicense object is constructed with
*
myName == name && myAge
&& age && myIdNumber == number
*
&& myPrey == prey && myDoePermit == doePermit.
*/
public DeerHuntingLicense(String name,
int age, int number,
boolean
doePermit)
{
super(name, age, number,
"Deer");
myDoePermit = doePermit;
}
//--- Accessor ---
public boolean getDoePermit() { return myDoePermit; }
//--- Mutator ---
public void setDoePermit(boolean
doePermit) { myDoePermit = doePermit; }
//--- Output method ---
/** toString converter
*
Return: a String representation of a DeerHuntingLicense
*/
public String toString()
{
return super.toString()
+
" -- Doe hunting is" + (getDoePermit() ? " " : " not ")
+
" allowed";
}
//--- Attribute variables ---
private boolean myDoePermit;
}
//-- Driver to
test license hierarchy
import
ann.easyio.*;
import
License.*;
import
HuntingLicense.*;
import
DeerHuntingLicense.*;
class
LicenseDriver
{
public static void main(String [] args)
{
License l
= new
License("John Doe", 19, 12345);
Screen theScreen = new
Screen();
theScreen.println(l +
"\n");
HuntingLicense h
= new
HuntingLicense("Mary Doe", 18, 54321, "Doves");
theScreen.println(h +
"\n");
DeerHuntingLicense d
= new
DeerHuntingLicense("Joe Blow", 66, 66666, true);
theScreen.println(d);
}
}
Output
John Doe
19 years old
ID: 12345
Mary Doe
18 years old
ID: 54321
Prey: Doves
Joe Blow
66 years old
ID: 66666
Prey: Deer --
Doe hunting is allowed
25.
(a)
/**
BankAccount.java provides a class to model bank accounts.
*/
import
ann.easyio.*;
public
class BankAccount extends Object
{
/** BankAccount constructor
*
Receive: String name, int number,
double balance
*
Postcondition: A BankAccount object is constructed with myName == name
*
&& myAccountNumber == number && myBalance == balance.
*/
public BankAccount (String name, int
number, double balance)
{
myName = name;
myAccountNumber = number;
myBalance = balance;
}
//--- Accessors ---
public String getName() { return
myName; }
public int getAccountNumber() { return
myAccountNumber; }
public double getBalance() { return myBalance; }
//--- Output method ---
/** toString converter
*
Return: a String representation of a BankAccount
*/
public String toString()
{
return "Account
Number: " + getAccountNumber()
+ "
Balance: $" + getBalance();
}
//--- Attribute variables ---
protected String myName;
protected int myAccountNumber;
protected double myBalance;
}
(b)
/**
CheckingAccount.java provides a class to model checking accounts.
*/
import
ann.easyio.*;
public
class CheckingAccount extends BankAccount
{
/** CheckingAccount constructor
*
Receive: String name, int number,
double balance,
*
double serviceCharge
*
Postcondition: A CheckingAccount object is constructed with
*
myName == name && myAccountNumber == number
*
&& myBalance == balance
*
&& myServiceCharge == serviceCharge.
*/
public CheckingAccount(String name, int
number, double balance,
double serviceCharge)
{
super(name, number,
balance);
myServiceCharge =
serviceCharge;
}
//--- Accessor ---
public double getServiceCharge() { return myServiceCharge; }
/** Deposit method ---
*
Receive: amount of a deposit
*
Postcondition: myBalance is increased by amount
*/
public void deposit(double amount)
{
myBalance += amount;
}
/** Withdrawal method ---
*
Receive: amount of a withdrawal
*
Postcondition: myBalance is decreased by amount
*/
public void withdraw(double amount)
{
myBalance -= amount;
}
//--- Output method ---
/** toString converter
*
Return: a String representation of a CheckingAccount
*/
public String toString()
{
return super.toString() +
"\nService Charge: $" + getServiceCharge();
}
//--- Attribute variables ---
protected double myServiceCharge;
}
(c)
/** Loan.java provides a
class to model loans.
*/
import ann.easyio.*;
public class Loan extends
BankAccount
{
/** Loan constructor
* Receive: String
name, int number, double balance,
*
double interestRate
*
Postcondition: A Loan object is constructed with
*
myName == name && myAccountNumber
== number
*
&& myBalance == balance
*
&& myInterestRate == interestRate.
*/
public Loan(String name, int number, double balance,
double interestRate)
{
super(name, number, balance);
myInterestRate = interestRate;
}
//--- Accessor ---
public double getInterestRate() { return myInterestRate; }
/** Make-payment method ---
* Receive: amount of
a payment
*
Postcondition: myBalance is decreased by amount
*/
public void makePayment(double amount)
{
myBalance -= amount;
}
/** Add-interest method ---
*
Postcondition: myBalance is increased by amount of interest
*/
public void addInterest()
{
double interest = myBalance * myInterestRate;
myBalance += interest;
}
//--- Output method ---
/** toString converter
* Return: a String
representation of a Loan
*/
public String toString()
{
return super.toString() + "\nInterest Rate
= " + getInterestRate();
}
//--- Attribute variables ---
protected double myInterestRate;
}
26.
/** StudentLoan.java provides a class to model
student licenses.
*/
import ann.easyio.*;
public class StudentLoan extends Loan
{
/**
StudentLoan constructor
* Receive: String name, int number,
double balance,
*
double payment, int numMonths
* Postcondition: A StudentLoan object is
constructed with
*
myName == name && myAccountNumber
== number
*
&& myBalance == balance && myMonthlyPayment == payment
*
&& myLoanTerm == numMonths
*
&& myCurrentPaymentNumber == 0.
*/
public
StudentLoan (String name, int number, double balance,
double interestRate, double
payment,
int numMonths)
{
super(name, number, balance, interestRate);
myMonthlyPayment = payment;
myLoanTerm = numMonths;
myCurrentPaymentNumber = 0;
}
//---
Accessor ---
public
int getLoanTerm() { return
myLoanTerm; }
public
double getMonthlyPayment() { return myMonthlyPayment; }
/**
Make-payment method ---
* Receive: amount of a payment
* Postcondition: myBalance is decreased
by amount and
*
myCurrentPaymentNumber is incremented by 1.
*/
public
void makePayment()
{
myBalance -= myMonthlyPayment;
myCurrentPaymentNumber++;
}
/**
Payments remaining method ---
* Return: number of payments remaining
*/
public
int paymentsLeft()
{
return myLoanTerm - myCurrentPaymentNumber;
}
//---
Output method ---
/**
toString converter
* Return: a String representation of a
StudentLoan
*/
public
String toString()
{
return super.toString() + "\nLoanTerm = " + getLoanTerm()
+
" months\nMonthly Payment: $" + getMonthlyPayment();
}
//---
Attribute variables ---
private int myLoanTerm,
myCurrentPaymentNumber;
private double myMonthlyPayment;
}
//-- Driver to test bank account hierarchy
import ann.easyio.*;
import BankAccount.*;
import CheckingAccount.*;
import Loan.*;
import StudentLoan.*;
class AccountDriver
{
public
static void main(String [] args)
{
BankAccount ba
= new
BankAccount("John Doe", 12345, 500.00);
Screen theScreen = new Screen();
theScreen.println(ba + "\n");
CheckingAccount ca
= new
CheckingAccount("Mary Doe", 54321, 500.00, 5.00);
theScreen.println(ca + "\n");
ca.deposit(100.00);
theScreen.println("Deposit $100:\n" + ca + "\n");
ca.withdraw(50.00);
theScreen.println("Withdraw $50:\n" + ca + "\n");
Loan l = new Loan("Joe Blow", 66666, 600, .01);
theScreen.println(l);
l.makePayment(50.00);
theScreen.println("Pay $50:\n" + l);
l.addInterest();
theScreen.println("Add interest:\n" + l + "\n");
StudentLoan sl
= new
StudentLoan("Joe Blow", 66666, 600.00, .05, 25.00, 15);
theScreen.println(sl);
sl.makePayment();
theScreen.println("MakePayment:\n" + sl);
theScreen.println(sl.paymentsLeft() + " payments left.");
}
}
Output:
Account Number:
12345 Balance: $500.0
Account Number:
54321 Balance: $500.0
Service Charge:
$5.0
Deposit $100:
Account Number:
54321 Balance: $600.0
Service Charge:
$5.0
Withdraw $50:
Account Number:
54321 Balance: $550.0
Service Charge:
$5.0
Account Number:
66666 Balance: $600.0
Interest Rate =
0.01
Pay $50:
Account Number:
66666 Balance: $550.0
Interest Rate =
0.01
Add interest:
Account Number:
66666 Balance: $555.5
Interest Rate =
0.01
Account Number:
66666 Balance: $600.0
Interest Rate =
0.05
LoanTerm = 15
months
Monthly Payment:
$25.0
MakePayment:
Account Number:
66666 Balance: $575.0
Interest Rate =
0.05
LoanTerm = 15
months
Monthly Payment:
$25.0
14 payments
left.