Library Hits

You are to develop a program, which can handle statistics for the number of visitors (hits) at the different home pages at the Fantasy Library.

This class would probably be one of many statistics classes for the library, like: Borrower_Statistics, Lend_Statistics, Hits_Statistics etc….

Imagine that from the requirement specification and the various diagrams in OOD the following objectives has been identified for HitsStatistics (or just Hits):

Comment: Hits can be seen as a controller class controlling hits on each home page or as a domain class holding the statistical information.
The choice depends on the viewpoint of the problem domain. In this exercise we choose the last interpretation

We want a program which can calculate and print out something like:

page  hits of home pages
------------------------
0     1234
1     1567
2     200
.
.
7     785

maximum number of hits: 1567 (page no. 1)
minimum number of hits: 200 (page no. 2)
total number of hits: 7216
mean number of hits: 902
standard deviation: 139.76

Part 1:   Problem Domain class data
First create a class Hits with the following data fields:

int[] data: an integer array with unknown size
int indexMax: the index (page number) of the maximum number of hits in data
int max: the maximum of hits in data

Compile it.

Tip: Very similar to Exam Statistics in the book !!

Part 2:   Function class methods
Then extend the class with the following constructor and method:

public Hits(int noOfPages): the constructor declaring the data array with the size noOfPages and initializing all the element values to 0
public String toString(): returns a String with indices and values seperated by line-breaks ("\n")
public setValue(int idx, int visitors): assigns the value (visitors) to the array (data) at index idx

Tip: Very similar to exercise Arrays

Part 3:   Application class
Create an application class, HitsApp, with the usual main() method.
In main() you must declare and construct a variable of the Hits class and print out the data.

Now, initialize the data using a loop that runs through all index'es and sets a random value between 100 and 3000.
Tip: use (int) (Math.random() * 2900 + 100) to get a random value between 100 and 3000

Finally print out the data again.

For the sake of simplicity let us assume that 8 pages are in play.

The HitsApp class must resemble the following template:

public class HitsApp {

  public static void main(String[] args) {

    // Declaration of an instance of the Hits-class

    // print the data by using the toString() method

    // initialize by making a loop that calls the
    // Hits-objects setValue(int, int) method, first argument
    // is the index, second argument is the random value

    // print the data again using the toString() method

  }//main(String[]
}HitsApp

Compile and run

Remark: You have now a simple program , which can be expanded by more complex methods
First KISS, then we extend!

Part 4:  Total hits
Expand Hits with a method, total(), which can traverse the data and return the sum of all values.
In HitsApp show how the total number of hits can be printed out

Part 5:   Mean
Expand Hits with a method, mean(), which uses total() and returns the mean value.
In HitsApp show how the mean number of hits can be printed out

Part 6:   Maximum values
Expand Hits with a method, getMax(), which can traverse the data and find the maximum value in data.
Also expand Hits with a method, getMaxIndex(), which returns the index of the maximum value.
In HitsApp show how the methods can be used to print out the maximum value and the index of maximum.

Part 7:   Minimum values
In the same way show how the minimum values can be found in Hits and used in HitsApp.

Part 8:   Standard deviation
Expand Hits with a method, stdDeviation(), which can calculate the standard deviation and return it.
In HitsApp show how this method can be used.

Part 9:   Initializing data by copying
Expand Hits with a new constructor:

Hits(int[] newData): constructor declaring the data array with the length of newData and initializing (copying) the data elements to the values of newData array.

In HitsApp show how this constructor can be used.

Part 10:   Sorting
Expand Hits with a method, sort(), which can sort the data array and return this sorted integer array, without spoiling the original data array.
In HitsApp show how this method can be used to print out the sorted set of data.

Part 11:   Requirements and use cases
This is a group work question to be solved in your system development group. Look at the program made so far:
Identify a list of requirements in analysis
Identify a list of use case probably leading to the methods programmed
Describe one of the more complex use cases