Answer Posted / tntrichy

Hi Bal, Virtual Function concept in Java, i.e, assigning
sub-class object in super-class's reference.

Can I use % with real numbers?

1017

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Can I learn java in 3 months?

1022

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What is an array length?

897

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What is the format specifier?

923

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Explain 5 features introduced in jdk 1.7?

1018

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What is quick sort in java?

1007

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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)

1945

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What are user defined exceptions?

1038

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What is a null check?

998

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Which class is used by server applications to obtain a port and listen for client requests?

963

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Have you ever used hashtable and dictionary?

1012

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What is mvc in java?

1011

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In a program, initializing an array of 100 KB is throwing an out of memory exception while there is 100 MB of memory available. Why?

1050

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What is java algorithm?

930

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What is the Difference between Final Class && Abstract Class?

1071

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