Answer Posted / kusum

if a variable is declared static only single copy is
visible to all instances of class.if a method is declared
as static it is executed first as how main method is
executed in java

How to instantiate static nested classes in java?

1025

---

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)

1886

---

What is the use of 'super' keyword inside a constructor?

918

---

What is regex used for?

954

---

What is the numeric promotion?

959

---

What is the purpose of the main method?

951

---

Why do we create threads in java?

1160

---

How to use string tokenizer class.

1140

---

Can It is possible to synchronize the constructor of a Java Class?

1049

---

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

919

---

List any five features of java?

974

---

What is a class variable?

992

---

Does every java program need a main?

948

---

How many types of threads are there in java?

1003

---

How do you sort data in java?

910

---