Assignment 7: Inheritance, Vectors, Recursion

Due date: Thursday March 4th, 11:59pm by e-mail

1. Paying Staff Members Example

Write the code for a hierarchy of classes that classifies staff members.

There should be a class Staff_Member that serves as the root of the hierarchy.

The rest of the hierarchy should be designed based on the following:

• Because Volunteers do not get paid, they are not considered to be Employees. However, they share many common characteristics with employees, such as name, username, and telephone number.

• Unlike Volunteers, Employees get paid and they have a pay_rate which is the amount that they get on pay day (their salary).

  Among Employees two categories have additional features as far as pay is concerned:

  • For Executives the pay is the regular salary plus a one time bonus.

  • For Hourly employees the pay is computed by multiplying the number of hours worked with the pay rate.

Additional help with problem 1.

2. Write Your Own Vector Class

Define your own Vector class then use the Stack class defined in class, that relies on Vector, to test your code. (No longer import java.util in your test program, instead use the Vector class you define.)

Your Vector objects should be able to respond to the following messages:

void addElement (Object obj)

Adds the object to the end of the vector, increasing its size by one.

boolean contains (Object obj)

Returns true if the object is among the values stored in the vector, or false otherwise.

Object elementAt (int index)

Returns the object at the specified index position.

int indexOf (Object obj)

Returns the index position of the first instance of the object in the vector (if the object is in the vector) or -1 otherwise.

int indexOf (Object obj, int index)

Same as above, but starts the search from the specified index.

void insertElementAt(Object obj, int index)

Inserts the object at the specified index position, after shifting down objects at and below the insertion point.

boolean isEmpty ()

Returns true if the vector contains no objects, or false otherwise.

void removeElement (Object obj)

Removes the first occurrence of the specified object, and then shifts up objects at and below the deletion point.

void removeElementAt(int index)

Deletes the object at the specified index position, and then shifts up objects at and below the deletion point.

void setElementAt (Object obj, int index)

Replaces the existing object at the specified index position with the specified object.

int size ()

Returns the number of objects currently stored in the vector.

HELP in getting started writing your own Vector class.

3. Recursive Calculator

Define a class Calculator whose instances will be able to compute (recursively) the n^th element of each of the following three recurrences:

1. T(0) = 0
   T(n) = 2 * T(n-1) + 1, for n > 0

2. C(1) = 1
   C(n) = 1 + C(n / 2), for n even and
   C(n) = 1 + C(3 * n + 1), for n odd

3. J(1) = 1
   J(n) = 2*J(n/2) - 1, if n > 1 is even, and
   J(n) = 2*J((n-1)/2) + 1, if n > 1 is odd