Interview Question and Answers | Search Coding Interview Questions - javasearch.buggybread.com
Javasearch.buggybread.com

Search Interview Questions


 More than 3000 questions in repository.
 There are more than 900 unanswered questions.
Click here and help us by providing the answer.
 Have a video suggestion.
Click Correct / Improve and please let us know.
Label / Company      Label / Company / Text

   



Interview Questions and Answers

   next 30
 Q131. What is the difference between inner class and sub class ?Core Java
Ans. Inner Class is a class that is nested within another class whereas sub class is a class that extends or inherit another class.

Inner class can only be accessed using reference of outer class ( Class name , if inner class is static or object reference, if inner class is non static ) whereas Sub class is accessed directly.

In terms of memory, inner class is stored just like another class having it's own body whereas sub class carries the body of parent class as well as it's own fields in memory.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     inner classes  nested classes  inner class vs sub class  nested class vs sub class      Basic


 Q132. What is the difference between Graph's Breadth first and Depth First algorithm ?Algorithm
Ans. In Breadth first algorithm, all the adjacent nodes of the starting node is visited first and then the same rule is followed while moving inwards whereas

In Depth first algorithm, all the nodes of a single traversal path are visited first till a cycle or an end is found.

For example , given the following entries of adjacent nodes

1,2
1,3
1,6
2,4
2,5
3,6

The Breadth first path would be

1,2,3,6,4,5

and Depth first path would be

1,2,4,5,3,6

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     graph traversal  breadth first vs depth first        frequent


 Q133. Is this a valid initialization ? Explain.

Collection<Collection> collection = new LinkedList<LinkedList>();
Core Java
Ans. No. It will result in a type mismatch error.

Collection<Collection> collection = new LinkedList<Collection>();

is a valid initialization as collection being reference of "Collection" class can hold object of derived Class "LinkedList" due to runtime Polymorphism. Runtime polymorphism is not applicable to type arguments.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     generics  type argument


 Q134. What are the benefits of using Wrapper classes over primitive types ?Core Java
Ans. With Collection classes , we cannot use primitive types. Moreover for any class using generic types, we cannot use primitive types.

They add more functionality by means of additional methods.

As their reference can be null , they offer consistent check for uninitialized state.

They facilitate caching and reuse by means of constant Pools.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     wrapper classes  benefits of wrapper classes over primitives


 Q135. If arrays cannot be resized , Why is this code valid

String[] strArray = new String[2];
strArray = new String[5];
Core Java
Ans. We are not resizing the first array here but assigning the reference strArray to a new Array with size 5.

So after line 2, We have 2 arrays in memory, one with size 2 and other with size 5 with strArray referring to second array with size 5.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     arrays  array initialization


 Q136. Design an e commerce application using AWS ? What AWS services will you use ?Amazon Web Services (AWS)
Ans. CloudFront for Static Media and cached content
EC2 and EKS ( Docker ) for main application computing
RDS and DynamoDB for Database
Lambda ( computing ) for running back end cron jobs
Kinesis for streaming and SQS for queuing
CloudWatch for Monitoring
CloudFormation for Infrastructure templating
S3 for Object Storage

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     


 Q137. Difference between Region , Availability zone and Edge Locations ?Amazon Web Services (AWS)
Ans. A Region is a Geographical entity like US-East , US-West etc. Each Region may have multiple availability zones where each zone comprise of 1 or more Data Center located with each other.

Edge Locations are the sites that hosts cached content for faster delivery and for saving network traffic as they feed content from sites that are local or near to consumption.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     aws region  aws availability zone  aws edge location  region vs availabillity zone


 Q138. What are the different S3 storage Tiers ?Amazon Web Services (AWS)
Ans. S3 Standard
S3 IA - Infrequently Accessed
S3 One Zone IA - One Zone only , Infrequently Accessed
S3 Glacier - achieved

S3 Standard is most expensive , Glacier is least expensive

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     aws s3  aws storage  amazon cloud storage  amazon s3


 Q139. What are the factors on which customers are charged for using S3 ?Amazon Web Services (AWS)
Ans. Storage Tier ( IA , Standard , Glacier etc )
Storage ( Volume of Data )
No of Requests
Meta Data
Data Transfer Speed acceleration through cache and Edge Location

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     aws s3  aws storage  amazon cloud storage  amazon s3


 Q140. What are the factors on which price classes are based on in case of EC2, S3, CloudFront and EBS ?Amazon Web Services (AWS)
Ans. EC2 - Time and Reservation , Instance Type ( Memory , Computation power )
S3 - Accessibility Frequency , Data Transfer , Storage Space
CloudFront - Geography, No of Locations
EBS - IOPS, Access Frequency

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     aws ec2  aws computing  amazon cloud computing  amazon ec2  aws s3  aws storage  amazon cloud storage  amazon s3  aws cloudfront  amazon cloudfront  aws ebs


 Q141. What are the different Route53 routing policies ?Amazon Web Services (AWS)
Ans. Simple
Weighted
Latency
Failover
GeoLocation
Multivalue

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     aws route53     Asked in 1 Companies


 Q142. What is the relationship between VPC and subnet ? Can you tell with an example ?Networking
Ans. A VPC is devided into multiple subnets. Subnet in a particular VPC could be public or private.

For Example - A particular account may have multiple vpc's for each of the business type. For each Business or VPC , One can have different subnets to cater to each department so that access across departments could be restricted. But still there could be identities that have control over different subnets. Moreover we could have multiple subnets for each department so as to have distinguished public and private networks having different types of applications ( public facing or internal consumption )

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     aws vpc  aws subnet  subnet  vpc  Amazon Web Services (AWS)


  Q143. What are the different types of inner classes ?Core Java
Ans. Simple Inner Class,
Local Inner Class,
Anonymous Inner Class,
Static Nested Inner Class.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     java   inner classes   classes     Asked in 6 Companies      basic        frequent

Try 1 Question(s) Test


Frequently asked in Indian Service Companies. Tech Mahindra ( Based on 3 inputs ) and Infosys ( 3 inputs )
  Q144. What is the difference between List, Set and Map ?

or

What are the different Java Collections Interfaces ?
Core Java
Ans. List - Members are stored in sequence in memory and can be accessed through index.
Set - There is no relevance of sequence and index. Sets doesn't contain duplicates whereas multiset can have duplicates.
Map - Contains Key , Value pairs.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     java   collections   list   set   map   list vs set vs map     Asked in 8 Companies      basic        frequent

Try 1 Question(s) Test


  Q145. Does Java support Multiple Inheritance ?Core Java
Ans. Java doesn't support multiple inheritance. Interfaces does't facilitate inheritance and hence implementation of multiple interfaces doesn't make multiple inheritance.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     java   oop   oop concepts   inheritence   multiple inheritence   basic interview question     Asked in 10 Companies      basic        frequent

Try 1 Question(s) Test


Frequently asked at HCL Technologies ( Based on 3 feedback )
  Q146. Difference between Checked and Unchecked exceptions ?Core Java
Ans. Checked exceptions are the exceptions for which compiler throws an errors if they are not checked whereas unchecked exceptions are caught during run time only and hence can't be checked.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     java   exceptions   checked exceptions   unchecked exceptions   exception handling   checked vs unchecked exceptions     Asked in 39 Companies      basic        frequent

Try 1 Question(s) Test


Very frequently asked. Favorite question in Walk in Drive of many Indian service companies.
  Q147. What is a Final Variable ?Core Java
Ans. Final variable is a variable constant that cannot be changed after initialization.

  Sample Code for final variable

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     oops   java   final   final variable   basic interview question     Asked in 12 Companies      basic        frequent

Try 1 Question(s) Test


 Q148. When are static variables loaded in memory ?Core Java
Ans. They are loaded at runtime when the respective Class is loaded.

  Sample Code for static variable

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     java   oops   static   static variable   memory      intermediate


 Q149. Can we serialize static variables ?Core Java
Ans. No. Only Object and its members are serialized. Static variables are shared variables and doesn't correspond to a specific object.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     serialization   java   oops   static   static variables     Asked in 1 Companies      intermediate        rare

Try 2 Question(s) Test


 Q150. Can we use null as a key for a map collection ?Core Java
Ans. Yes , for HashMap. HashMap implements Map interface. HashMap allows one null key and any number of null values.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     java   collections   hashmap   map   hashtable   yes-no     Asked in 1 Companies


Usually asked only to fresh graduates.
 Q151. What is the difference between time slicing and preemptive scheduling ?Operating System
Ans. In preemptive scheduling, highest priority task continues execution till it enters a not running state or a higher priority task comes into existence. In time slicing, the task continues its execution for a predefined period of time and reenters the pool of ready tasks.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     operating system   scheduling   threads   multi threading        rare


 Q152. What one should take care of, while serializing the object?
Ans. One should make sure that all the included objects are also serializable. If any of the objects is not serializable then it throws a NotSerializable Exception.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     serialization   java   oops   object      expert


 Q153. How many bits are used to represent Unicode, ASCII, UTF-16, and UTF-8 characters?
Ans. Unicode requires 16 bits and ASCII require 7 bits. Although the ASCII character set uses only 7 bits, it is usually represented as 8 bits. UTF-8 represents characters using 8, 16, and 18 bit patterns. UTF-16 uses 16-bit and larger bit patterns.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     character coding   ascii   unicode   utf

Try 1 Question(s) Test


 Q154. Are constructors inherited? Can a subclass call the parent's class constructor? When?Core Java
Ans. You cannot inherit a constructor. That is, you cannot create a instance of a subclass using a constructor of one of it's superclasses. One of the main reasons is because you probably don't want to override the superclasses constructor, which would be possible if they were inherited. By giving the developer the ability to override a superclasses constructor you would erode the encapsulation abilities of the language.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     java   oops   constructor   inheritence     Asked in 1 Companies      expert        rare

Try 1 Question(s) Test


 Q155. Is Apache an application or Web server ?
Ans. Web server.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     apache   web server   j2ee


 Q156. Difference between Abstract and Concrete Class ?Core Java
Ans. Abstract classes are only meant to be sub classed and not meant to be instantiated whereas concrete classes are meant to be instantiated.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     java   oops   abstract classes   Abstract vs Concrete Class     Asked in 1 Companies      basic        frequent


  Q157. Difference between Vector and ArrayList ?Core Java
Ans. Vectors are synchronized whereas Array lists are not.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     java   basic interview question   vector   arraylist   collections   synchronization   vector vs arraylist     Asked in 35 Companies      basic        frequent


  Q158. What is the use of Transient Keyword ?Core Java
Ans. It in Java is used to indicate that a field should not be serialized.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     java   oops   serialization   transient   java keywords     Asked in 39 Companies      intermediate        frequent

Try 2 Question(s) Test


Very Frequently asked. Usually asked along with String Class related questions.
  Q159. What is an immutable class ?Core Java
Ans. Class using which only immutable (objects that cannot be changed after initialization) objects can be created.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     java   oops   immutable  immutability   immutable  immutability class   string class   basic interview question     Asked in 18 Companies      Basic        frequent

Try 2 Question(s) Test


 Q160. Difference between object instantiation and construction ?Core Java
Ans. Though It's often confused with each other, Object Creation ( Instantiation ) and Initialization ( Construction ) are different things in Java. Construction follows object creation.

Object Creation is the process to create the object in memory and returning its handler. Java provides New keyword for object creation.

Initialization is the process of setting the initial / default values to the members. Constructor is used for this purpose. If we don't provide any constructor, Java provides one default implementation to set the default values according to the member data types.

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     java   oops   constructor   object instantiation


previous 30   next 30

Help us and Others Improve. Please let us know the questions asked in any of your previous interview.

Any input from you will be highly appreciated and It will unlock the application for 10 more requests.

Company Name:
Questions Asked: