Answer Posted / ravikiran(aptech mumbai)

static variable is a class variable which value remains
constant for the entire class
static method is the one which can be called with the class
itself and can hold only the staic variables

Which of the following classes will have more memory allocated?

970

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What is the use of conditional statement?

929

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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)

1873

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Why string is immutable with example?

904

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What is the difference between JDK and JVM?

1174

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Why hashmap is used in java?

1007

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Can you extend singleton class?

1034

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What is byte data type?

941

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What is the java reflection api? Why it’s so important to have?

923

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How many decimal digits is 64 bit?

868

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Does java have extension methods?

911

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What is a dynamic array java?

884

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Can we override tostring method in java?

921

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What is a static method in java?

985

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Explain the difference between association, aggregation and inheritance relationships.

1025

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