Answer Posted / k.rajasekhar naidu

OOPS Concepts:
1) Encapsulation: Wrapping up of data and methods in to a
single unit is called as encapsulation.

2) Abstraction: It Supports Abstarction

3) Inheritence:Process of Aquiring properties from one
object to another without changes.

4) Polymorphism:Process of aquiring properies from one
object to anotherwith changes.

poly=many

morphism=forms

5) Message Passing:message passing is possible from one
object to another.

6) Robust and Secure: every object is strong one.
every object is secure one with their access specifiers.

What is java console application?

1015

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How do you convert string to int in java?

1080

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What is the impact of declaring a method as final?

1019

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Write a program to show whether a graph is a tree or not using adjacency matrix.

1098

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What is Recursion Function?

1208

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What is the latest java version?

1067

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What is prefix of a string?

1041

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Can we override private constructor in java?

981

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What is the importance of finally block in exception handling?

1032

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What is the difference between public, private, protected, and friend access?

1047

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What is final keyword in java? Give an example.

1016

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Why string is not thread safe?

1010

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What are the main uses of this keyword?

1066

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What is __ init __ functions?

1128

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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)

1947

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