Object-Oriented Programming (Narva College) 2018/19 spring

slides_s5.pdf

Task 1. University

(Classes Person, Student, Employee, Faculty, Staff, MyDate). Implement a class called Person and two subclasses of Person named Student and Employee. Make Faculty and Staff subclasses of Employee. A person has a name, address, phone number, and e-mail address. A student has a class status (freshman, sophomore, junior, or senior). Define the status as a constant (no set method). An employee has an office, salary, and date-hired. Define a class named MyDate that contains the fields for a year, month, and a day. A faculty member has office hours and a rank. A staff member has a title. Override the toString() method in each class to display the class name and the person's name.

Create a class called TestPerson. Create instances for different classes. Add these instances into a list (ArrayList<Person>) and print information about each person.

Task 2. Bank

Look at Account class in file Account.java

/**
 A class for bank accounts.

 This class provides the basic functionality of accounts.
 It allows deposits and withdrawals but not overdraft
 limits or interest rates.   
 @author Stuart Reynolds ... 1999
 */

public class Account {
    private double bal;  //The current balance
    private int accnum;  //The account number


    public Account(int a) {
        bal=0.0;
        accnum=a;
    }

    public void deposit(double sum) {
        if (sum>0)
            bal+=sum;
        else
            System.err.println("Account.deposit(...): "
                    +"cannot deposit negative amount.");
    }

    public void withdraw(double sum) {
        if (sum>0)
            bal-=sum;
        else
            System.err.println("Account.withdraw(...): "
                    +"cannot withdraw negative amount.");
    }

    public double getBalance() {
        return bal;
    }

    public double getAccountNumber() {
        return accnum;
    }

    public String toString() {
        return "Acc " + accnum + ": " + "balance = " + bal;
    }

    public final void print() {
        //Don't override this,
        //override the toString method
        System.out.println( toString() );
    }

}

Write main method in a different class to briefly experiment with some objects of Account class.

Using Account class as a base class, write two derived classes called SavingsAccount and CurrentAccount. A SavingsAccount object, in addition to the attributes of an Account object, should have an interest variable and a method which adds interest to the account.

A CurrentAccount object, in addition to the attributes of an Account object, should have an overdraft limit variable. Ensure that you have overridden the methods of Account class as necessary in the derived class.

Now create a class called Bank. An object of this class has to contain an array of Account objects. Accounts in the array could be instances of Account class, SavingsAccount class, or CurrentAccount class. In the client class, create a bank and some test accounts (some of each type). Print out information about each account state (current balance).

Bank class requires methods for opening and closing accounts, and for paying a dividend into each account.

Task 3. Heroes

An agency has a file which contains a list of heroes. The list contains hero's names and their location. Some sample rows in the file look like this:

 Superman* / London
 Batman / Tokyo
 Spiderman / Los Angeles

The list contains a few superheroes which are marked with * near the name.

1. Class Hero has private instance fields: name (String), place (String). The class has at least one constructor. The class also has at least the following methods:

• get and set methods for the all instance fields.
• rescue method of int type: the method takes in the number of people to rescue as an argument (int) and returns the number of rescued people (which is always equal to 95 percent of the people to be rescued and rounded to the whole number).
• toString method which shows information about the hero in a readable way.

2. SuperHero class is a subclass of Hero class. There is no need to rewrite the instance fields of the superclass. SuperHero class has also an instance field for the skill level (double) which varies between [1-5).

The class has at least one constructor which initialises also the superhero's skill level. The class also has at least the following methods:

• rescue method is overridden so that the method returns the number of rescued people; the number of the rescued people is (95 + skill level) percent of all the people to be rescued.
• toString method which is overridden so that it contains toString method of the superclass and adds info about the superhero's skill level.

3. In the main class, there should be at least the following variables and methods:

• a variable for the list of heroes.
• static void method which reads in the data from the file given as an argument. Using the data from the file, the corresponding instances of Hero and SuperHero classes are created and added to the list (Note: create the file yourself. Mark superheroes with *).

Apply rescue method to at least one hero and to at least one superhero. Show info about the heroes and superheroes.