Core Java interview Questions

1.    What is the difference between object and class?

2.    What is difference between overloading and overriding?

3.    What is aggregation and Composition?

4.    What is difference between abstract class and interface?

5.    How will you create an object without using 'new' operator?

6.    Explain about Thread life cycle?

7.    What is difference between StringBuffer and StringBuilder?

8.    What is hashcode?

9.    Explain the use of synchronization block

10. How will make a method() Thread-safe

11. Explain about Serializable and Externalizable interface

12.  Explain Object comparison using ‘==’ and equals() method

13.  When will go for LinkedList vs ArrayList

14. What is static method and static block ?

15. When will you use Hashmap vs TreeMap?

16.  What are the types of exception in java

17.  Write a code snippet for singleton design pattern

18.  What is multi-threading?

19. What is the difference between sleep() and wait() method

20.  How to call an external process in java

21.  What is Lambda expression?

22. What is Functional interface?

23. Difference between Iterator vs Enumeration vs Spliterator?

24. What is Priority Queue?

25.  What are types of Class Loaders available in Java

26. What is a Generic Type Parameter?

27. What is a Wildcard type?

28. What is an Upper Bounded Wildcard?

29. What is a Lower Bound Wildcard

30. What is an Unbounded Wildcard?

Happy Reading and All the best for your interview!!

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AWS Basic Interview Questions

1) What are the Storage solution are available with AWS Cloud Platform

       EBS, Glacier, EFS, Storage Gateway, Cloudfront, S3

2) How to move 100 TB of data from your Data Center to AWS Cloud

3) What is auto scaling?

4)  What services are available in AWS Cloud for Devops Activity?


5) What is difference between Elastic BeanStalk and EC2 instance?

6)  Difference between SPOT instance and on demand instance?

7) Difference between Dedicated instance vs Reserved instance?


8)Difference between RDS & Dynamo DB - Give me a scenario.

9) What types of services are available in AWS to handle Data Stream?


10)  Explain Twelve factor app?

11)  What is AMI?

12) What services are available to process huge volume of data in AWS Cloud?

Happy Reading and All the best for your interview!!

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Oracle BPEL Questions


Interview questions for tech leads

Interview Questions for Architects and Tech Leads

1) Java Memory management concepts

Young Generation, Old Generation, Permanent Generation, Heap

 2) Garbage collector Algorithms

SerialGC (Mark and sweep) , ParallelGC, Concurrent Mark and Sweep

 3) Deadlock Scenario and how to resolve

 4) Whats new in Java 1.8 or 1.9 compare to 1.7

java 1.8 - Lambda expression, Stream API, Parallel Array Sorting, Base64 encoding implemention

Java 1.9 - JShell, Process API, HTTP 2.0 client support


 5) Design Patterns

  Adapter, Factory , Façade, Proxy, Singleton, Strategy

 6) Integration (Tools, Frameworks, Scenarios & Design)

DataStage, Oracle SOA Suite, Apache Camel, Mule, Servicemix

 7) Security (Authentication & Authorization, Encryption)

OWSM (Oracle Webservice Security Management)

 8) API Gateways Concepts

Vordel Gateway, Apigee, Oracle API Gateway,

 9) Sprint Boots (End to End implementation flow)

Controller->Service->DAO Component - > Data

 10) Knowledge on Spring Modules


11) ORM Frameworks

Hibernate, Apache Open JPA, TOPLink

12) Micro Services and SOA Concepts


 13) Problematic Scenario and design recommendation

Solving Security (Sign-on) for Web Services/ RestAPI

 14) Unix Concepts

  Shell scripts,network

 15) Application Servers like weblogic, Webpshere) Administration Activity

Datasource, JMSSetup, Security ACL,

 16) Maven Life Cycles, Build, Jenkins, Ansible Devops Concepts

 17) RestAPI Frameworks

Jersery, Jello, RestFulie

18) NOSQL Concepts

 MongoDB & DynamoDB

 19) Collection usage Scenario

Hashset, Hashmap,Linklist, Treeset,

 20) Oracle SQL Concepts

 Inner Join, Outer Join, Left and Right SQL Queries

 21) Deployment Strategy

Bladelogic, Ansible Script, Jenkin Deployment Process

 22) Caching concepts

Coherence Cache, EhCache

 23) Design tools

Architect, Visio, TogetherJ, SmartDraw

24) Performance tuning techniques

APM Tools (XREBEL), JMeter, jstat, jmap, thread dump analyzier, JProbe

 25) UI frameworks

 Websocket, AngularJS, ReactJS

 26) Messaging concepts – Async communication

JMS, IBM MQ,  RabbitMQ, AQS SQS

 27) Monitoring tools

Wily, BSM

 28) Knowledge on Elastic Search


 29) Testing /PerformanceTools and Frameworks

Selenium, JUnit, Mockito, Postman, Load Runner , JMeter

30) Architecture Tiers/Layers Approach

2 Tier, 3 Tier, N-Teir Architecture

31) IOT  Architecture

32) Data Lake Concepts

33) Difference between Virtual Machine and Dockers... Give a scenario for these two

34) Explain BlockChain

35) Explain about Graph Database

36) Explain about Chatbot

Happy Reading and All the best for your interview!!

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BPEL, Service Bus Interview Question


AWS Basic Interview Questions

Oracle BPEL, Service Bus And Mediator Interview questions

How do you pass soap headers information from BPEL 1 to BPEL 2 ? Explain the steps.. 

Explain the implementation steps to call BPEL process from springbean component in oracle soa suite space 

Can you tell me some Performances tuning parameters of Oracle BPEL engine? 

How do you achieve singleton in BPEL process 

What is usage of configuration plan file in Oracle SOA Suite

What is usage of flowN activity in BPEL and explain with a realtime scenario and Pros and Cons. 

Can you explain me about fault framework (Life cycle) 

Explain me about Resequencing concepts of oracle mediator and Pros and Cons?

How do you update the endpoint of your external web services from BPEL process during runtime 

Can you explain on dehydration activity in BPEL process with a real time example
Can you explain the usage of composite.xml 

Want to post a message to an external jms queue from my BPEL process can you explain the steps to achieve this.

Explain the usage of routing/service callout/publish of Oracle Service Bus with a realtime example 


Explain the transaction setting for sync and Asyn service calls in Oracle Service Bus. 

Happy Reading and All the best for your interview!!

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