Answer Posted / sunny

Deep cloning - You clone the object and their constituent parts.

This kind of cloning is adequated when the parts of the
object make up the object, and can not be separated from it.

A car HAS four wheels, and to clone (copy) a car, I must
clone their four wheels.

Shallow cloning - You clone only the object, not their
parts. You add references to their parts.

This kind of cloning is adequated when the parts of the
object are independent of it.

An entry in an address book has the street name, the city
name. To clone that entry, you simply add references to the
street and city names.

That distinction is a little difficult to be done in Java,
but is better understood if you think in terms of databases.

You need deep cloning if the entity requires "cascade
deleting" to be deleted. You need shallow cloning if
"cascade deleting" is not needed.

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The following program reads data (details of students) from a file named students.txt and converts it into e-mail addresses. The results are written to a file named studentemail.txt. students.txt consists of a number of lines, each containing the data of a student in colon delimited format: Last Name:First Name:Student Number Each input record is converted to an e-mail address and written to studentemail.txt in the following format: the first character of the last name + the first character of the first name + the last four digits of the student number + “@myunisa.ac.za” import java.io.*; public class EmailConverter { public static void main(String[] args) throws IOException { BufferedReader input = new BufferedReader(new FileReader ("students.txt")); PrintWriter output = new PrintWriter(new FileWriter ("studentemail.txt")); String line = input.readLine(); while (line != null) { // Extract the information for each student String[] items = line.split(":"); // Generate the email address String email = "" + items[0].charAt(0) + items[1].charAt(0) + items[2].substring(4,8) + "@myunisa.ac.za"; email = email.toLowerCase(); // Output output.println(email); line = input.readLine(); } input.close(); output.close(); } } Rewrite the class so that it handles possible errors that may occur. In particular, it should do the following: • It should catch at least three appropriate exceptions that might occur, and display suitable messages. • At this stage, the program will not run correctly if there is an empty line in the input file. Change the program so that if an empty line is encountered, an exception is thrown and the empty line is ignored. This exception should be handled with the display of a suitable error message. • Before the e-mail address is added to the output file, check if the student number has 8 digits. If not, throw an InvalidFormatException (which the program should not handle itself)

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