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Design - Interview Questions and Answers for 'Abs' - 35 question(s) found - Order By Newest

Very frequently asked. Among first few questions in almost all interviews. Among Top 5 frequently asked questions. Frequently asked in Indian service companies (HCL,TCS,Infosys,Capgemini etc based on multiple feedback )
  Q1. Difference between == and .equals() ?Core Java
Anonymous
Ans. "equals" is the method of object class which is supposed to be overridden to check object equality, whereas "==" operator evaluate to see if the object handlers on the left and right are pointing to the same object in memory.

x.equals(y) means the references x and y are holding objects that are equal. x==y means that the references x and y have same object.

Sample code:

String x = new String("str");
String y = new String("str");

System.out.println(x == y); // prints false
System.out.println(x.equals(y)); // prints true

  Sample Code for equals

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   Like         Discuss         Correct / Improve     java   string comparison   string   object class   ==    equals   object equality  operator     Asked in 289 Companies      basic        frequent

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Very Frequently asked. Have been asked in HCL Technologies very frequently ( based on 3 feedback ). Among first few questions in many interviews.
  Q2. Differences between abstract class and interface ?Core Java
Admin
info@buggybread.com
Ans. Abstract classes can have both abstract methods ( method declarations ) as well as concrete methods ( inherited to the derived classes ) whereas Interfaces can only have abstract methods ( method declarations ).

A class can extend single abstract class whereas it can implement multiple interfaces.

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   Like         Discuss         Correct / Improve     java   classes   abstract class   interfaces     Asked in 64 Companies      basic        frequent


Almost sure to be asked in every company using any Dependency Injection framework ( Spring, Guice etc )
  Q3. What is Dependency Injection or IOC ( Inversion of Control ) ?Design

Ans. It is a Design Pattern that facilitates loose coupling by sending the dependency information ( object references of dependent object ) while building the state of the object. Objects are designed in a manner where they receive instances of the objects from other pieces of code, instead of constructing them internally and hence provide better flexibility.

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   Like         Discuss         Correct / Improve     design patterns   ioc ( Inversion of Control )  dependency injection     Asked in 80 Companies      intermediate        frequent


 Q4. Difference between Factory and Abstract Factory Design Pattern ?Design
Anonymous
Ans. Factory Pattern deals with creation of objects delegated to a separate factory class whereas Abstract Factory patterns works around a super-factory which creates other factories.

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   Like         Discuss         Correct / Improve     java   design pattern   factory design pattern   abstract factory design pattern   technical lead      expert


Very frequently asked.Usually among first few questions.
  Q5. What is MVC ? Design
Anonymous
Ans. MVC is a Design Pattern that facilititates loose coupling by segregating responsibilities in a Web application

1. Controller receives the requests and handles overall control of the request
2. Model holds majority of the Business logic, and
3. View comprise of the view objects and GUI component

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   Like         Discuss         Correct / Improve     j2ee   mvc   mvc design pattern   design pattern   struts   spring   web application   web frameworks   ebay     Asked in 60 Companies      basic        frequent

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 Q6. If you are given a choice to implement the code to either Insert a Record or Update if already exist, Which approach will you follow ?

1. Insert into the DB Table. If exception occurs, update the existing record.
2. Check if the record exists and update it if it exists, If not insert a new record.
Solution
admin
info@buggybread.com
Ans. In first case, there would be 2 DB calls in worst case and 1 in best case. In 2nd approach there will be always 2 DB calls.

Decision on the approach should depend on the following considerations -

1. How costly is the call to DB ? Are we using indices , hibernate etc

If calls to DB are costly , 1st approach should be the choice.

2. Exception Book keeping load upon exception.

The benefit of saving 1st call in approach 1 should be bigger than the Book keeping for the exception.

3. Probability of the exception in first apparoach.

If the DB Table is almost empty, it makes sense to follow Approach 1 as majority of the 1st calls will pass through without exception.

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   Like         Discuss         Correct / Improve     database   insert-update   db exceution plan   db strategy   design   architecture   technical lead


  Q7. What is the use of Transient Keyword ?Core Java
Anonymous
Ans. It in Java is used to indicate that a field should not be serialized.

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   Like         Discuss         Correct / Improve     java   oops   serialization   transient   java keywords     Asked in 38 Companies      intermediate        frequent

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 Q8. Write a program to show thread usage in Java by implementing runnable interface2017-08-03 12:16:07

Ans. public class MyClass {
   static class MyThreadClass implements Runnable{

      public void start() {
         Thread t = new Thread(this,"threadName");
         t.start();
      }
      
      @Override
      public void run() {
         System.out.println("Hello");
         try {
            Thread.sleep(1000);
            System.out.println("Hello Again");
         } catch (InterruptedException e) {
            e.printStackTrace();
         }
         
      }
      
   }
   
   public static void main(String[] args){
      MyThreadClass myThreadClass = new MyThreadClass();
      myThreadClass.start();
      
      MyThreadClass myThreadClass2 = new MyThreadClass();
      myThreadClass2.start();
   }
}

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   Like         Discuss         Correct / Improve     Threads  runnable interface


 Q9. Difference between Factory and Strategy Design Pattern ?Design
Anonymous
Ans. Factory is a creational design pattern whereas Strategy is behavioral design pattern. Factory revolves around the creation of object at runtime whereas Strategy or Policy revolves around the decision at runtime.

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   Like         Discuss         Correct / Improve     java   design pattern   factory   strategy   creational design pattern   behavioral design pattern     Asked in 1 Companies      expert


 Q10. What is a Cursor ?Database
Admin
info@buggybread.com
Ans. It's a facility that allows traversal over the records pulled from a table or combination of tables. Its like iterator in Java.

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   Like         Discuss         Correct / Improve     databases   sql   cursors   packages     Asked in 5 Companies      basic        frequent


Very frequently asked. Usually followed by questions related to private constructor and synchronized access. Frequently asked in JPMorgan and TCS (Based on 2 feedback)
  Q11. Explain Singleton Design Pattern ?Design
Admin
info@buggybread.com
Ans. http://www.buggybread.com/2014/03/java-design-pattern-singleton-interview.html

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   Like         Discuss         Correct / Improve     java   design pattern   singleton   at&t   ebay  fidelity india  united healthcare india     Asked in 46 Companies      intermediate        frequent


Frequently asked in face to face interviews.
  Q12. Write a program to print fibonacci series.Core Java

Ans. int count = 15;
int[] fibonacci = new int[count];
fibonacci[0] = 0;
fibonacci[1] = 1;
for(int x=2; x < count; x++){
fibonacci[x] = fibonacci[x-1] + fibonacci[x-2];
}

for(int x=0; x< count; x++){
System.out.print(fibonacci[x] + " ");
}

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   Like         Discuss         Correct / Improve     ebay   fibonacci series     Asked in 65 Companies      basic        frequent


 Q13. Does it make sense to clone an object which is supposed to be immutable ?Design2016-07-28 20:54:59

Ans. It make sense only if we intend to modify either of the object and would like to preserve original state in other. Otherwise we can reuse the original object by making it singleton.

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   Like         Discuss         Correct / Improve     clone  clone objects  prototype design pattern   immutable  immutability  immutability  cloning


 Q14. Design an online shopping site system ?Design2016-12-13 11:06:10

Ans. AWS Services - CloudFront for distribution / caching, EC2 for computing, EBS for block storage , S3 for object storage , RDS for database , Kinesis for streaming , CloudWatch for monitoring.

Technologies - Java for back end with Spring Boot , Angular , RxJs for front end .

Architecture - Service Oriented. Multi layer.

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   Like         Discuss         Correct / Improve          Asked in 1 Companies


 Q15. What is a factory design pattern ?Design2017-01-09 13:21:43

Ans. Factory Design Patterns is the pattern that recommends creation of separate Factory Object for creation of other object.

So its like saying - If you want to create an object of ClassA, Talk to FactoryObject ( which is an object of FactoryClass ). FactoryObject in itself encapsulates the inputs and logic required to make the decision regarding the creation and construction of object.

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   Like         Discuss         Correct / Improve     design pattern  factory design pattern     Asked in 9 Companies


 Q16. Difference between Singleton and Factory Design Pattern ?Design2017-02-02 11:24:01

Ans. Both are creational design patterns but singleton facilitates in creation and reuse of single object whereas Factory deals with creation of multiple objects.

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   Like         Discuss         Correct / Improve     Design pattern  singleton  factory  singleton vs factory     Asked in 4 Companies


 Q17. Design a Database Schema to store Employee Information with each employee having multiple addresses. Database2017-08-24 13:48:56

Ans. We can have 2 entities i.e EMPLOYEE and ADDRESS and can have a relationship Table , EMPLOYEE_ADDRESS having one to may relationship between the two.

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   Like         Discuss         Correct / Improve     database schema   design     Asked in 2 Companies


 Q18. What is the programming advantage of Immutability ?Design2018-03-31 08:33:05

 This question was recently asked at 'Overstock.com'.This question is still unanswered. Can you please provide an answer.


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   Like         Discuss         Correct / Improve     mmutable  immutability  immutabilit     Asked in 1 Companies


 Q19. What are the disadvantages of immutability ?Design2018-03-31 08:33:36

 This question is still unanswered. Can you please provide an answer.


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 Q20. What is immutability and What are it's disadvantages ?Design2018-06-20 12:20:19

 This question was recently asked at 'Bloomberg'.This question is still unanswered. Can you please provide an answer.


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   Like         Discuss         Correct / Improve     immutable  immutability objects   immutability     Asked in 1 Companies


 Q21. Design database schema for Facebook like application.Database2018-06-21 18:01:57

 This question was recently asked at 'Symantec'.This question is still unanswered. Can you please provide an answer.


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   Like         Discuss         Correct / Improve     database design     Asked in 1 Companies      expert


Library Management System has always been the favorite question. This questions is asked irrespective of level.
 Q22. Write data models and service end points for Library Management System ?Architecture2018-06-30 13:43:10

Ans. Following could be the business sub domains or database schemas in such a system

1. Users / Members
2. Sourcing
3. Inventory Management
4. Operations

Following services end points could be there

1. Users - addNewUser ( put ), removeUser ( post )
2. Sourcing - addSupplier ( put ), removeSupplier ( post )
3. Inventory Management - getInventory ( get )
4. Operations - checkIn ( post ), checkout ( post )

There could be following Tables in Database

1. Users / Members - MEMBER, MEMBERSHIP_TYPE
2. Sourcing - SUPPLIER, SUPPLIER_PRODUCT, PRODUCT_REORDER_LEVELS
3. Inventory Management - INVENTORY,PRODUCTS
4. Operations - TRANSACTION

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   Like         Discuss         Correct / Improve     database  architecture  design     Asked in 1 Companies


 Q23. How to avoid cloning, serialization in the singleton class ?Design2019-01-04 10:12:26

Ans. For Cloning-exception,For deserialization-read.resolve()

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   Like         Discuss         Correct / Improve     singleton  cloneable  serializable  serialization  cloning     Asked in 1 Companies


 Q24. Create DB schema for Employee, Department.Database2019-04-06 12:42:21

 This question was recently asked at 'RiseSmart India,RiseSmart'.This question is still unanswered. Can you please provide an answer.


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   Like         Discuss         Correct / Improve     db schema  database schema  database design     Asked in 2 Companies


 Q25. Find the second largest array element without sorting?Design2019-08-07 13:14:31

 This question was recently asked at 'VinnovateLabz'.This question is still unanswered. Can you please provide an answer.


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   Like         Discuss         Correct / Improve          Asked in 1 Companies


 Q26. Write a Program to swap 2 variables ( using 3rd variable )Core Java2017-07-25 19:41:20

Ans. int x = 1;
int y = 2;
int z = x;
x = y;
y = z;

System.out.println("x="+x);
System.out.println("y="+y);

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   Like         Discuss         Correct / Improve     swap 2 variables  code  coding     Asked in 1 Companies      basic


 Q27. Write a Program to swap two variables ( without using 3rd variable )2017-07-25 19:42:32

Ans.
int x = 1;
int y = 2;

x = x+y;
y = x-y;
x = x-y;

System.out.println("x="+x);
System.out.println("y="+y);

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   Like         Discuss         Correct / Improve     swap 2 variables


 Q28. Which method needs to be implemented if a class is implementing comparable interface ?Core Java
a. comp
b. compare
c. compareTo
d. compareEquals

Ans.c. compareTo

 Q29. What is Dirty Read in Database Transactions ?Database
a. Data Read by Transaction 2 which hasn't yet updated by Transaction 1
b. Data Read by Transaction 2 which has been updated and commited by Transaction 1
c. Data Read by Transaction 2 which has been updated but not commited by Transaction 1
d. Inability of Transaction 2 to read Data when Transaction 1 is updating.

Ans.c. Data Read by Transaction 2 which has been updated but not commited by Transaction 1

 Q30. Which of the following is not true for abstract classes ?Core Java
a. Abstract Class is only meant to be sub classed and not supposed to be instantiated.
b. Abstract class handlers can be used to handle derived class objects.
c. We can't have an abstract class without abstract methods.
d. Abstract class has member elements.

Ans.c. We can't have an abstract class without abstract methods.

 Q31. Which of the following class creates immutable objects ?Core Java
a. String
b. StringBuffer
c. StringBuilder
d. None of these create immutable objects.

Ans.a. String

 Q32. Which of the following can be declared abstract ?Core Java
a. static methods
b. instance methods
c. static variable
d. instance variables

Ans.b. instance methods

 Q33. In majority of the cases, the following join will give maximum number of results ?Database
a. Inner Join
b. Outer Join
c. Left Join
d. Right Join

Ans.b. Outer Join

 Q34. Which if the following is true for SQL Joins ?Database
a. Left Join and Right Join gives equal number of Results
b. Outer Join and Inner Join gives equal number of Results
c. Inner Join gives maximum number of results records
d. Inner Join gives minimum number of result records

Ans.d. Inner Join gives minimum number of result records

 Q35. Which of the following is not true for Prepared Statements ?Database
a. Prepared Statements provides better performance
b. Prepared Statements prevent SQL Injection attacks
c. Prepared Statements provide ORM capabilities
d. Prepared Statement provides DB side caching

Ans.c. Prepared Statements provide ORM capabilities



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