GTU MCA III (SM): June 2010

GUJARAT TECHNOLOGICAL UNIVERSITY
MASTER OF COMPUTER APPLICATION
SEMESTER: III

Subject Name: Programming Skills-IV (Java/ Statistical Methods)
Subject Code: 630006

Suggested Practicals for Java and Statistical Methods:

1. Observe the interactions involved in the process of booking a railway ticket. Identify the various
objects involved and the interactions between the objects in order to solve a problem of booking a
railway ticket.

2. Write a simple java application to print a pyramid with 5 lines. The first line has one character, 2nd
line has two characters and so on. The character to be used in the pyramid is taken as a command
line argument.

3. Write a Java application which takes several command line arguments, which are supposed to be
names of students and prints output as given below:
(Suppose we enter 3 names then output should be as follows):

Number of arguments = 3
1: First Student Name is =Tom
2: Second Student Name is =Dick
3: Third Student Name is =Harry
Hint: An array may be used for converting from numeric values from 1 to 20 into String.

4. Write a class, with main method, which declares floating point variables and observe the output of
dividing the floating point values by a 0, also observe the effect of assigning a high integer value
(8 digits and above) to a float and casting it back to int and printing.

5. Write a class called Statistics, which has a static method called average, which takes a one-
dimensional array for double type, as parameter, and prints the average for the values in the array.
Now write a class with the main method, which creates a two-dimensional array for the four weeks
of a month, containing minimum temperatures for the days of the week(an array of 4 by 7), and
uses the average method of the Statistics class to compute and print the average temperatures for
the four weeks.

6. Define a class called Product, each product has a name, a product code and manufacturer name.
Define variables, methods and constructors, for the Product class. Write a class called Test
Product, with the main method to test the methods and constructors of the Product class.

7. Define a class called Cartesian Point, which has two instance variables, x and y. Provide the
methods get X() and get Y() to return the values of the x and y values respectively, a method called
move() which would take two integers as parameters and change the values of x and y respectively,
a method called display() which would display the current values of x and y. Now overload the
method move() to work with single parameter, which would set both x and y to the same values, . Provide constructors with two parameters and overload to work with one parameter as well. Now
define a class called Test Cartesian Point, with the main method to test the various methods in the
Cartesian Point class.

8. Define a class called Triangle, which has constructor with three parameters, which are of type
Cartesian Point, defined in the exercise 7. Provide methods to find the area and the perimeter of
the Triangle, a method display() to display the three Cartesian Points separated by ':' character, a
method move() to move the first Cartesian Point to the specified x, y location, the move should
take care of relatively moving the other points as well, a method called rotate, which takes two
arguments, one is the Cartesian Point and other is the angle in clockwise direction. Overload the
move method to work with Cartesian Point as a parameter. Now define a class called Test Triangle
to test the various methods defined in the Triangle class. Similarly also define a class called
Rectangle which has four Cartesian Point.

9. Override the to String, equals and the hash Code methods of the classes Triangle and Rectangle
defined in exercises 7 and 8 above, in appropriate manner, and also redefine the display methods
to use the to String method.

10. Define an abstract class called Polygon. Provide a constructor which takes an array of Cartesian
Point as parameter. Also provide method called perimeter, which calculates and returns the
perimeter of the Polygon. Declare abstract method area for this class. Also define a method called
move, which takes two parameters x and y to specify the destination for the first point of the
Polygon, and overload to make it work for Cartesian Point as a parameter. Now update the classes
Triangle and Rectangle in the exercise 8 above, to be a subclass of the Polygon class. Write
appropriate class with main method to test the polymorphism in the area method.

11. Make the class Cartesian Point, belong to a package called edu. gtu. geometry, the classes Polygon,
Triangle and Rectangle belong to the package edu. gtu. geometry. shapes and the classes Test
Cartesian Point, Test Triangle, Test Rectangle and Test Polygon belong to the package edu. gtu.
test. Use appropriate access specifiers for the classes and the members of the classes defined in the
earlier exercises. Now onwards all the classes must be defined in a package.

12. Update the classes Triangle and Rectangle, to throw an exception if the Cartesian Point instances
passed as parameter does not specify an appropriate Triangle or Rectangle. e.g. In case of Triangle,
if the three points are in a straight line, or in case of Rectangle, if the lines when connected cross
each other.

13. Define a class called Polygon Manager, which manages a number of Polygon instances. Provide
methods to add, remove and list the Polygon instances managed by it. Test the methods of Polygon
Manager by writing appropriate class with main method.

14. Define a class called Statistical Data which manages a number of readings of type int. Provide a
method to set Data available in the form of an array, a method add to individually add data of type
int, a method to reset the entire data, and methods to return the following statistics:

1. mean
2. median
3. mode
4. variance
5. standard deviation
6. specified percentile (between 0 – 100) the method should have a parameter. 7. specified quartile (between 1 - 3) the method should have a parameter.
8. interquartile range

Use this class to calculate the given statistics for the data regarding the total of marks obtained by
all the students in your class in the previous exams. The data may be accepted one by one for each
student from the keyboard.

15. Update the class Statistical Data, and define a method called load From CSV, which takes as
parameter an Input Stream, where numeric data is available in an ASCII format, in a comma
separated form. Overload this method to take a File instance as parameter. Test the new methods
using appropriate data.

16. A college maintains the information about the marks of the students of a class in a text file with
fixed record length. Each line in the file contains data of one student. The first 25 characters have
the name of the student, next 12 characters have marks in the four subjects, each subject has 3
characters. Create a class called Student Marks, which has student Name, and marks for four
subjects. Provide appropriate getter methods and constructors, for this class. Write an application
class to load the file into an array of Student Marks. Use the Statistical Data class to compute the
statistics mean, median, mode, standard deviation and itnerquartile range for each of the subjects
in the class.

17. In the above exercise, use multithreading, to compute the statistics, after loading the Student Marks
from the file, for marks information available for different classes available from files placed in a
directory. Create at least five files in a directory with fixed record length to test your code.

18. In the class Statistics defined earlier add method to find the percentile for a given data value. Use
this to find your percentile ranking your class, during the last exam.

19. A Frequency Distribution is a tabular summary of data showing the number (frequency) of items in
each of several nonoverlapping classes. These classes may represent qualitative or quantitative
data. Create a class called Frequency Distribution, which provides a method called load From File,
to load data Strings from a file, and compute the Frequency Distribution for the various kinds of
Strings available from the file. The class should provide a method to print the frequency
distribution, and another to print the percent frequency distribution in a tabular manner. Test this
class by using the sample data available regarding purchases of best selling paperback business
book available from a file containing the abbreviated names of the book separated by white spaces.

20. Create subclass of the Frequency Distribution class called Frequency Distribution Quantitative,
which provides method called add Class Range, which takes two numbers as parameter. The class
should maintain a number of class ranges, and should ensure that the class ranges are
nonoverlapping. The load From File method should be overridden to compute frequency
distribution of numeric data loaded from the file, it should discard the data which does not fall in
any of the class ranges. Test this class by using the sample data available regarding the waiting
times of patient arriving at a clinic of a doctor for emergency service.

21. Update the FrequencyDistributionQuantitative class defined in exercise 19, and adds a method to
reset the data and the class ranges. Also add a method called set Range Interval, which specifies
the size of each class Range and the starting value, this should be used at building the
nonoverlapping class ranges as the data is loaded, now only the data less than the starting value
may be discarded while loading numeric data from the file. Test this class by using the data
regarding the salary of marketing executives available in a file. Set the starting value as 5,000 and have intervals of 500.

22. Create a class called Stem and Leaf, which should have a provision to maintain the stem size and
the number of intervals between the two stems. It should also have a method to load the data from
the file and a method to display the stem-and-leaf diagram for the loaded data. Test the class to
display data regarding the marks of students of your class in the previous exam.

23. Create a class called Pie Canvas, which subclasses from the java. awt. Canvas class, and overrides
the paint method to display the Pie Chart for the data available from an instance of Frequency
Distribution. Provide a method to set the instance of Frequency Distribution, on the Canvas. Test
this class by adding it into a Frame and using the Frequency Distribution instance created for data
regarding the top selling books prepared for exercise 18.

24. Create a class called Statistical Data, which has capability of maintaining data regarding multiple
variables. It should have a method to specify the variable names as String array and the method to
load values from a file regarding the variables. eg. We consider two variables as percentage of
marks in GCET exam and percentage of marks in 1st
year of MCA, Provide methods in the class to
compute the correlation coefficient between any two variables, specified in the parameter. Test the
class by computing the correlation coefficient between the marks of GCET and marks of 1st
year
MCA for students of your class.

25. Simple random sampling uses a sample of size n from a population fo size N to obtain data that
can be used to make inferences about the characteristics of a population. Suppose that, from a
population of 50 bank accounts, we want to take a random sample of four accounts in order to
learn about the population. How many different random samples of four accounts are possible.
Write a Java class which can compute the number of random samples for size n from a population
of N, Also provide method to display all possible samples, and also a method to return a sample,
derived from the possible samples. (Hint use random method of the Math class to select the
random sample).

26. Dasher is an information-efficient text-entry interface, driven by natural continuous pointing
gestures. Dasher is a competitive text-entry system wherever a full-size keyboard cannot be used.
Dasher is a zooming interface. You point where you want to go, and the display zooms in wherever
you point. The world into which you are zooming is painted with letters, so that any point you
zoom in on corresponds to a piece of text. The more you zoom in, the longer the piece of text you
have written. You choose what you write by choosing where to zoom. To make the interface
efficient, we use the predictions of a language model to determine how much of the world is
devoted to each piece of text. Probable pieces of text are given more space, so they are quick and
easy to select. Improbable pieces of text (for example, text with spelling mistakes) are given less
space, so they are harder to write. The language model learns all the time: if you use a novel word
once, it is easier to write next time.

Write a class in Java which models the probabilities for the alphabets in a language as the starting
alphabet and then the probatilities for the subsequent alphabets which may follow the alphabet and
so on leading to the end of word. The probabilities may be built by reading a text file containing
lots of texts in the given language. (Hint: create a class to represent a node, which has an alphabet
and its probability and each node has capability of maintaining a list of subsequent nodes).
(Advanced question)

27. Write a class in Java to plot a Histogram for the data available from the instance of Statistical Data
class defined in exercise 24 earlier. Make a provision for selecting the variables for which Histogram is to be plotted.

28. Write a class in Java to plot a Scatter diagram for the data available from the instance of Statistical
Data class defined in exercise 24 earlier. Make a provision for selecting the variables for which
scatter diagram is to be plotted.

29. Define a class which implements the Table Model for displaying the data available from the
Statistical Data instance of exercise 24, in a tabular form. Use instance of this model to create an
instance of J Table and display the data of exercise 24 in tabular format.

30. Create an applet which has a Text Field to accept a URL string, and displays the document of the
URL string in a new browser window.

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