Java interview questions actually asked in IT companies

Hi friends,

Here in this post, I'm sharing Java interview questions actually asked in multiple I.T companies interviews.
I'll also provide the answers to these questions in my next post. I'll provide the link [URL] for this post.

So, here are list of questions actually asked in I.T. companies @ 10+ years of experience.

Aricent:

• Sort list of Employee objects using name, then phone and then email. [nth Level sorting]
• At runtime , how to change logs from info to debug using Log4j ?
• How to use JMeter for load testing?

BirdEye:

• Print all unique permutations of a String.
• Write your own BlockingQueue
• If Thread1 calls synchronized method in Singleton class, then can another
  thread call getInstance() [if synchronize(Singleton.class) is 1st statement in getInstance() method] method of Singleton class?
• Print all edge nodes of a Binary Tree.
• How locking mechanism is implemented by JVM?

Capgemini:

• How to handle transaction in Spring?
• What is ORM and how to use it?
• What is Heap dump?
• How does memory management in JDK8 work?
• Difference between serial and parallel streams.
• How to find OutOfMemoryError in production app? And how to avoid this error immediately for long time?
• What is internal structure of heap memory?
• How to configure GC in java application?
• What are Serial and Parallel GC's?
• What is Java memory model?

Concirrus:

• What is Singleton object? How it is used in Deserialization?
• Use clone on Singleton.
• How Hashmap works?
• What is immutable class and how to make a class immutable?
• How to detect loop in LinkedList?
• How to dynamically configure a microservice?
• Is there any loophole in using Git/Jenkins [CI/CD way]?
• How is TinyURL implemented?

EPAM:

• What are Locks in java?
• What is thread synchronization and what is Monitor concept?
• What is Functional interface in Java8?
• What are Optional Class and default method in interface? What are their benefit?
• Explain Decorator pattern.
• Explain Java memory model.
• Have you used Mockito? How?
• How does HashSet work?
• What is Generic Type in Java.
• What are Type Erasures in java?
• Difference between ArrayList and LinkedList?
• What is volatile keyword?
• What happens to Thread Stack, when a thread calls a method?
• Name all garbage collectors. Which is default garbage collector?
• How does parallel GC work?
• How does G1 work?
• Explain SOLID design principle.
• Difference between Weak reference and Strong reference.
• What are ACID properties of database?
• What is composition?
• What is REST implementation?

EVC Ventures: Part-I:

• Using SQL transaction with Spring
• Diff. b/w SQL transaction and Business transaction
• Diff. b/w Normal services on VM and Microservices.
• Using Service in Angular
• How a Login request from Template works in Angular?
• What are Spring Boot Starter projects?

EVC Ventures: Part-II:

• How an Exception with response code 400 is returned?
• What is Hibernate Versioning?
• How to ensure that some specific requests go to interceptor in Spring?
• Write a Generic class.

GSpann:

• What is Polymorphism?
• Can we have constructor in abstract class?
• What is multiple inheritance in java?
• Which data structure is used by HashMap internally?
• What changes have been made to HashMap in Java8?
• Types of exceptions?
• Do we use try catch in custom checked exception?
• Can we create custom exception for both checked and unchecked?
• What are Scopes in Spring?
• What is DI in Spring?

Infoblox:

• What is Method overloading?
• What is Method hiding?
• GoLang Vs Java
• How do you do Code Review?
• Do you have exp. in Cloud Services?
• Do you know about Containers?

Provar:

• How to avoid deadlocks?
• Memory specification of Objects[young gen, old gen, permanent gen]
• Difference between String object and String literal.
• HashMap and CocurrentHashMap. How HashMap works?
• What is Executor Framework?
• Which one is better: Using Synchronized block or synchronized method?
• What are CountDownLatch and CyclicBarrier?
• Which one is Default scope for Spring Bean? 

RBS:

• What is the diff. between PUT and POST. Which request you will use to recharge a mobile?
• What is the diff. between Collections API and Stream API?
• Is Stream API faster than Collection?
• Changes in Collection API in java 8?
• Have you used JProfiler. How does it works and why you will use it?
• What are MicroServices?
• What is REST API?
• Have you worked with Spring Boot?
• What are new features added in Java 8.
• Explain Stream Life cycle methods.

WDTS:

• What is ReentrantLock?
• What are MicroServices?
• What are REST call End Points?
• Explain Life cycle of Spring Bean.