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)
21
What are listeners in java and explain ?
190
Is there any use of an abstract class which has no methods
and no attributes?
Is it safe for adding 10,00,000 records/objects to
HashMap?, i.e is it safe to add millions of objects to
HashMap?
106
Name the components that are termed to be Heavy-weight
component but available in Light-weight components?
366
hi am an engineering student and my next plan is for ms in
either in us or australia i got my passport but i dont know
anything bout visa can u give brief idea
1)How to get prepared for visa and
2)How to apply for top universities and
3)How to pay the fee and so on
These all are basic questions plz give me a clear idea
74
What are the restrictions imposed by a Security Manager on
Applets?.
167
How to add and remove nodes in Jtree?
232
How listener identify that the event came from a particular
object?
107
how to one war file class to another war file class?
143
Say you want to store the information about a number of
pets in an array. Typical
information that you could store for each pet (where
relevant) would be
• Breed of animal
• Animal's name
• Its birth date
• Its sex
• Whether it has been sterilised or not
• When it is due for its next inoculation
• When it last had its wings clipped
For each type of pet (eg. dog, cat or bird) you would
typically define a class to hold
the relevant data.
Note: You do not need to implement these classes. Just
answer the following
questions.
3.1.1 What would be the advantage of creating a superclass
(eg. Pet) and
declaring an array of Pet objects over simply using an
array of Objects,
storing each of the instances of the different pet classes
(eg. Dog, Cat or
Bird) in it?
3.1.2 Would you define Pet as a class or as an interface?
Why?
(2)
(2)
16
23. Storage space in java is of the form
Stack
Queue
Heap
List
24. What is java code embedded in a web page known as
Applets
Servlets
scriptlets
snippets
25. Which of the following attributes are compulsory with
an <applet> tag?.
code,height & width.
26. What does 'CODEBASE' in an applet tag specify?.
Files absolute path.
How can we handle runtime exceptions? write one sample
program? Can we write runtime exceptions beside the throws
key word? if yes write sample program?
For ease of programming you can consider the maze as a 2D
array with colors represented by below integer and
characters (in capital letters).
• B - Black
• W -White
• G- Green
• R- Red
R B W B W W W W
W W
B W B B W W W W
W W
W B W B W W W B
W W
W W B B W W W B
W W
W B W W B B B B
W B
W B W W B W W W
B W
W W B B B W W B
W W
W B W W B W B W
W W
B W B W W W W B
B W
W W W B W W W W
W G
Shortest Route Problem:
• Solution that finds the shortest Route between Red
and Green
 White will have 1 Weight.
 Red and Green carry no weights.
 Shortest path is the path with less weight when you
add up the weights in the path.
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