4.1 FACTORIAL

Planning document USE CASE: FACTORIAL Scope: Factorial calculating application Primary actor: person who calculates a factorial Stakeholders and interests: -          Person who calculates a factorial: Desires accurate and fast calculation. Preconditions: Integer values between 0 and 31 are accepted on input; One command line parameter is expected; The user should be able start an application from console; J2SE installed on user’s PC. Main scenario Input Events from User System Events and Responses Start application with accepted parameter Calculate a factorial   Display a result   Extensions A.    User runs an application without parameter. Generate message how to use application. Quit application. B.     User inputs a parameter less than 0. Generate error message. Quit application. C.     User inputs a parameter greater than 31. Generate error message. Quit application. D.    Any other error. Generate error message. Quit application.

Inspection document 1. Bad format 2. Some comments should be there to make the code more understandable for an inspector

Code /** * This program calculates the factorial of n integer values. */ public class Factorial{ public static void main(String[] args){ if (args.length < 1 ) { //if no parameters, we tell how to use it System.out.println("Usage: java Factorial integer"); } else { try { int n = Integer.parseInt(args[0]); int fct = 1; // try to handle different values of n if ((n >= 0) && (n < 32)) { if (n > 0) { for (int i = 1; i <= n; i++){ fct *= i; } } System.out.println(n + "! = " + fct); } if (n >= 32){ System.out.println("This number is too big so integer type can't handle it."); } if (n < 0){ System.out.println("This number should be greater or equal to 0."); } } catch (Exception e) { System.out.println("I'm sorry! An error occurs"); System.out.println("Usage: java Factorial integer"); } } } }

4.2 AVERAGE

Planning document USE CASE: AVERAGE Scope: Calculation of average of list of integers application Primary actor: person who calculates an average Stakeholders and interests: -          Person who calculates an average: Desires accurate and fast calculation. Preconditions: A text file containing integer values; One command line parameter is expected; The user should be able start an application from console; J2SE installed on user’s PC. Main scenario Input Events from User System Events and Responses Start application with file name as a parameter Read values from a file   Calculate sum of values   Calculate the quantity of values   Calculate an average value   Display a result   Extensions A.    User runs an application without parameter. Generate message how to use application. Quit application.

Code /** * This program calculates the average of a list of integers. */ import java.io.*; public class Average { public static void main (String[] args){ if (args.length >= 1) { try{ BufferedReader in = new BufferedReader( new FileReader(args[0])); String line; int counter = 0; int sum = 0; while ((line = in.readLine()) != null) { sum += Integer.parseInt(line); //calculate sum counter++; //increase counter } sum /= counter; //finally calculate average System.out.println("Average of " + counter + " integers is " + sum); } catch (IOException e) { System.out.println("Usage: java Average file_name"); } } else { System.out.println("Usage: java Average file_name"); } } }

4.3

Planning document USE CASE: E-MAIL IDs Scope: E-mail ID generating application Primary actor: person who generates e-mail IDs Stakeholders and interests: -          Person who generates e-mail IDs: Desires accurate and fast result. Preconditions: Text file containing formatted strings with last name, first name, SSN; Text file to store results; The user should be able start an application from console; J2SE installed on user’s PC. Main scenario Input Events from User System Events and Responses Start application Open input file for reading   Open output file for writing   Read lines   Generate e-mail IDs   Save output file   Extensions A.    Wrong information in input file or any other error occurs. Generate message how to use application. Quit application.

Code import java.io.*; /** * This program generates student e-mail IDs. * input file is students.txt, output file is studentemail.txt */ public class Email { public static void main(String[] args) { try { BufferedReader in = new BufferedReader( new FileReader("students.txt")); PrintWriter out = new PrintWriter( new BufferedWriter( new FileWriter("studentemail.txt"))); String line, eml=""; int begin = 0, end; char delim = ':'; while ((line = in.readLine()) != null) { end = line.indexOf(delim, begin); eml = line.substring (end+1, end+2) + line.substring (0,1) + line.substring (line.length() - 4, line.length()); //generate e-mail ID eml += "@njit.edu"; // add domain to ID out.println(eml.toLowerCase()); // write ID to output file } out.flush(); out.close(); } catch (IOException e) { System.out.println("Usage: java Email"); } } }

4.7 CREATE PACKAGE

Planning document PACKAGE Scope: Create package from existing classes 1. Create directories for package 2. Copy classes to package directory 3. Add “package line” to classes source 4. Recompile applications 5. Run each application

Code I put programs to a such directory \myprog\single\ I have only added one line at the beginning of every code: package myprog.single; Than I recompiled programs and started them.

4.8 IMPROVED AVERAGE

Planning document USE CASE: IMPROVED AVERAGE Scope: Calculation of average of list of integers Primary actor: person who calculates an average Stakeholders and interests: -          Person who calculates an average: 1.      Accurate and fast calculation 2.      Exception handling with a meaningful message 3.      Application should ignore any lines in the input file that are other than a single integer   Preconditions: A text file containing integer values; One command line parameter is expected; The user should be able start an application from console; J2SE installed on user’s PC. Main scenario Input Events from User System Events and Responses Start application with file name as a parameter Read values from a file   Check string value   Calculate sum of values   Calculate the quantity of values   Calculate an average value   Display a result   Extensions A.    User runs an application without parameter. Generate message how to use application. Quit application.             B. Input file contains more than one integer or garbage in a line                   Skip the line without a message and continue calculation             C. Any other error.                  Submit meaningful message matching a kind of error

Code /* * This pogram prints out the average of the integers supplied in the variables.txt file * */ import java.io.*; public class Average { public static void main (String[] args){ if (args.length >= 1) { try{ BufferedReader in = new BufferedReader( new FileReader(args[0])); String line; int counter = 0; int sum = 0; boolean notInteger = false; while ((line = in.readLine()) != null) { for (int i=0; (i < line.length()); i++) { notInteger = false; // if line contains not an integer we skip this line without any message if ((!line.substring(i,i+1).equals("0")) && (!line.substring(i,i+1).equals("1")) && (!line.substring(i,i+1).equals("2")) && (!line.substring(i,i+1).equals("3")) && (!line.substring(i,i+1).equals("4")) && (!line.substring(i,i+1).equals("5")) && (!line.substring(i,i+1).equals("6")) && (!line.substring(i,i+1).equals("7")) && (!line.substring(i,i+1).equals("8")) && (!line.substring(i,i+1).equals("9"))) { notInteger = true; } } // calculate the sum, increase counter if (notInteger == false) { sum += Integer.parseInt(line); counter++; } } //calculate average, print out the result sum /= counter; System.out.println(); System.out.println("Average of " + counter + " integers is " + sum); } catch (IOException e) { System.out.println(); System.out.println("The file doesn't exist. Please, specify another one!"); } catch (NumberFormatException e) { System.out.println(); System.out.println("Incorrect value in the input file. Please, specify another one!"); } catch (ArithmeticException e) { System.out.println("Sorry. Some kind of arithmetic error!"); } } else { System.out.println(); System.out.println("Usage: java Average a_file_name"); // if incorrect file name } } }