Interested to Buy Any Domain ? << Click Here >> for more details...
Suppose there is an Online shopping cart application having
different objects like Cart, SelectionItem, Billing,
COnfiguration, Authentication, Authorization,
PersonalDetails etc. Out of this which one can be made a
singleton pattern and why?
- 2 Answers
- 10722 Views
- RBS, I also Faced
- E-Mail Answers
Answer Posted / sabir hussain
Singleton ensure that class has only one instance and
provide a global point of access to it.
It can be applied in a situation where your implementation
is independent and utilize resource that should be
initialized once within your application environment.
1) So Configuration can be singleton as we configure
resources that are globally used with your application. (ex:
database connection info.)
2) Authentication and Authorization component can also be
singleton as there implementation are independent and will
not solve any purpose if instantiated twice, if you look in
terms of spring framework all such components are singleton.
Both the component can independently authenticate or
authorize user or user info (validating credit card info).
Cart, SelectionItem and Billing are user specific generally
session scoped, and there can be more then one session per
application, so they cant be Singleton for obvious reason.
| Is This Answer Correct ? | 16 Yes | 2 No |
Post New Answer View All Answers
How do you generate random numbers in java?
What is static variable with example?
How many types of constructors are used in java?
How do you write methodology?
What is pangram in java?
Are global variables initialized to zero?
Can java object be locked down for exclusive use by a given thread?
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)
Explain the difference between serializable and externalizable in java?
Can we have a method name same as class name in java?
how to convert Java project into Maven ?
What is java command?
What is valid keyword in java?
Which number is denoted by leading 0x or 0x in java?
When is update method called?
