Assignment 1: Classes and Objects
1. Consider the following 'nonsense class'.
class A
{ public A() { n = 0; }
public A(int a) { n = a; }
public void f() { n++; }
public void g() { f(); n = 2 * n; f(); }
public int h() { return n; }
public void k() { System.out.println(n); }
private int n;
}
Identify the constructors, mutator functions, and accessor functions. What kind of
variable is n?
2. With the nonsense class from the preceding exercise, determine what the following
program prints.
public static void main(String[] args) {
A a = new A();
A b = new A(2);
A c = b;
A d = new A(3);
a.f();
b.g();
c.f();
d.g();
d.k();
A e = new A(a.h()
+ b.h()
+ c.h()
);
}
Work through the program by hand. Do not actually compile and run the program.
Then run it and compare the results.
3. Implement all the methods of the following class:
class Person {
public Person() {
….
}
public Person(String givenName, int yearOfBirth) {
……….
}
public String getName() {
…..
}
public String changeName(String name) {
……..
}
public int getAgeInYears(int currentYear) {
………
}
private String name;
private int birthdayYear;
public static void main(String[] args) {
……
}
}
Write a small test program that creates and works with objects of class Person as well.
Design exercises:
4. Implement a class Address. An address has
 a house number,
 a street,
 an optional apartment number,
 a city,
 a state and a
 postal code.
Supply two constructors:
 one with an apartment number
 and one without.
Supply a print function that prints the address with the street on one line and the city,
state, and postal code on the next line.
Supply a method compareTo that tests whether one address comes before another when
the addresses are compared by postal code.
5. Implement a class Account. An account has
 a balance,
 functions to add
 and withdraw money,
 and a function to inquire the current balance.
Pass a value into a constructor to set an initial balance.
If no value is passed the initial balance should be set to $0.
Charge a $5 penalty if an attempt is made to withdraw more money than available in
the account.
Enhance the Account class to compute interest on the current balance.
6. Implement a class Bank. This bank has two objects
 checking
 and savings
of the type Account that was developed in the preceding exercise.
Implement four instance methods:
deposit(double amount, String account)
withdraw(double amount, String account)
transfer(double amount, String account)
printBalances()
Here the account string is "S" or "C". For the deposit or withdrawal, it indicates which
account is affected. For a transfer it indicates the account from which the money is
taken; the money is automatically transferred to the other account.