CS35 Spring 2002
Homework 1
Due: Thursday January 31st before 2am (very late Wednesday night)

CONTENTS

• Assignment
• What to Hand In

You should work by yourself on this assignment.

• Problem #1: You will implement an Auto class, a Car class and a Truck class. Figure 1 shows the relationship between the classes and the list of data members and methods of each class (it is up to you to determine each data member's type). Each class will have a constructor that takes arguments to initialize all the relevant data. The Auto class will have two additional methods: (1) retailPrice, which returns the retail price of an Auto based on its cost and mark-up rate; and, (2) printAuto which prints the Auto's make, model, year, MPGs, and retail price. In addition, the Car and Truck classes should override the Auto class' printAuto method so that they print additional information that is unique to a Car or Truck. For example, a Truck object's printAuto method may print the following information (for now, don't worry about getting floating point numbers to be formatted in a particular way):

  	The 1992 Chevy Blazer:
  	--------------------- 
   	 14.6 MPG city
   	 27.3 MPG highway
   	 retail price is $18000.0
   	 Special Features:		
    	      * 8.0 ton capacity			
    	      * 4 wheel drive
    	      * Monster truck tires
    	      * cup holder
  
  

  In addition, you should create a RunAuto class containing a main method for testing your classes: create some Truck and Car objects and call their printAuto methods to print their information to stdout. The version of RunAuto.java that you turn in, should create 3 Truck and 3 Car objects and call the printAuto method of each object. You can use the same local variable for creating a Car or a Truck. For example:

  	// code inside main method 
  	Auto vehicle = new Car(< Car constructor args >);
  	vehicle.printAuto();
  	vehicle = new Truck(< Truck constructor args >);
  	vehicle.printAuto();
          ...
  

  Figure 1:
  
  

• Problem #2: Do exercise P-1.3 on page 54 of Goodrich and Tamassia. You can produce a sequence of psuedorandom numbers by creating an instance of the Random class and iteratively making calls to its nextInt (or nextLong, or ...) method. By invoking the constructor that takes a seed argument, you can get different starting points in the sequence of psuedorandom numbers. One way to get a "random" starting point is to use the return value of the getTime method of the Date class as the seed argument to Random's constructor:

  	Random random_date = new Random((new Date()).getTime());
  

  You only need to do the above one time in your program; only create one Random object. Once you have the Random object, you can then invoke one of its nextX methods to get the next random number as an int or a float or...

  You should create a Birthday class with a constructor that generates a valid random birthday. Note that for this problem the year someone is born does not matter. You should also create a RunBirthday class that executes the various experiments.

  Make sure that your program's output is in tabular format (you can use the tab character \t to ensure that entries in a column line-up). Something like this:

         # People      # Experiments     # Positive
         --------      -------------     ----------
         5             10                0
         10            10                0
         15            10                1
         20            10                3
         . 	     .                 . 
         . 	     .                 . 
         . 	     .                 .