Java interview question or CoreJava Interview question there are many topics when you are trying to attend an interview of Java.

Whether you have experience or are fresher this Java Interview question can help you crack the core java question.

If you are giving an interview in MNC companies these Java Questions will help you to crack it and MNC Companies like Capgemini, Wipro, Mphasis, L and T, oracle financial services, Atos Syntel, SCC global, Tech Mahindra, RR Donnelley, Coforge,  Citiustech, Citibank, Hdfc bank, TCS, etc...

Java Question
Java Interview Question

This Java Interview question will cover topics like Java OOP Concepts, Exception Handling, Threading, Collections, and Concurrency.

I will mention the question which is asked to an experienced mostly. You can also find this java interview of any fresher candidate.

Java Interviewer Question always keeps in mind that they are taking the interview as a Normal Java Interview. So they don't ask any difficult questions.

Here I would just put the  Java Interview questions, I am sure you can find answers to all these Java questions. Also, I have written some answers which can help you.

NOTE: The java question which is marked (Imp) and  (All Company Favorite Question) this question is very important for the interview.

Java Interviewer Question

Oops Question

1.  What is polymorphism in java?
2.  How to achieve polymorphism in java for example?
3.  When to use Interface and Abstract class in java?
4. What is the Different Between interface and abstract in java?
5. What is Serialization in java with Code Example? (Imp)
6. What is the serialVersionUID? (Imp)
7. What is used of serialVersionUID in Serialization? (Imp) Cititech,Capgemini, Wipro
8. What is the Volatile keyword in java? (Imp) Cititech, Oracle, Coforge, L and T, Capgemini, Wipro, HCL
9. How does the Volatile keyword work?
9. What are solid design principles in java?

String Question

1. What is Immutable in java?
2. Why String is Immutable in java?
3. When to use String, StringBuffer, or StringBuilder?
4. How to Create an Immutable class with Arraylist, Hashmap, or How to create an Immutable class with mutable object references in Java? (Cititech, Xoriant Company) You need to write code.

Java Collection Question

1. What is ArrayList in java? Internal Working of ArrayList in Java? (3+year Exp)
2. What is different between ArrayList and LinkedList in java? (Imp)
3. When to use ArrayList and LinkedList in java? (Imp)
4. Different between Set and List in java?
5. Internal Working of LinkedList in java? (3+year Exp).
6. Internal Working of HashSet in java? (Imp)
7. What is Comparator and Comparable interface in java?
8. What is the use of Comparator and Comparable in java?
9. Sorting using comparator in java?(All Company Favorite Question)  You need to wirte code.
10. What is Collections class used for in java?

Java Map Question

1. What is Map in java?
2. What is HashMap Map in java? Internal Working of HashMap in java? (All Company Favorite Question)
3. What is the load factor in hashMap in java?
4. Why do we need to override the equals and hashcode method in java? (All Company Favorite Question)
5.Fail Fast vs Fail Safe Iterator in Java
6. What is a concurrent modification Exception in java? (All Company Favorite Question)
7. How to handle concurrent modification Exception in java? (All Company Favorite Question)
8. How ConnurrentHashMap internally works in java? (All Company Favorite Question)
9. Different between HashMap and ConnurrentHashMap in java? (All Company Favorite Question)
10. In which scenario will ConnurrentHashMap fail in java?
11. Different Between Vector and ConnurrentHashMap in java?

Java Exception Interview Question

1. How do you handle Custom Exceptions in your project in java? (All Company Favorite Question)
2. What happens if we return a value in try and also return a value in finally, will finally execute? (All Company Favorite Question)
3. Different between throw and throws in java?
4. Exception overriding in java with some scenario (Imp)?
5. In which case finally block will not get Excreted (Imp)?

MultiThreading Interview Question

1. What is MultiThread in java(Imp)
2. Where have you used multithreading in your project? (All Company Favorite Question)
3. What are the ways to create a thread in java?
4. Which is the best way to create a thread from Runnable or Thread Class in java? (Imp)
5. How we can handle Multithreading in java?
6. What is synchronization in java and Why it is important? (All Company Favorite Question)
7. What are class level, object level, and Block level locks in synchronization java?
8. What is the Executor service framework in java or How to create a Thread pool in java? (Imp)
9. Why wait() notify() and notifyAll() methods are present in the object class? (Imp)
10. Why sleep() and yield() are static methods in thread class in java? (Wipro Company)
11. What is daemon thread in java? (Capgemini Company)

Garbage Collector and JVM

1. What is a garbage collector in java and How it Works in the JVM?
2. Ways of requesting JVM to run Garbage Collector in java?
3. Implementations or types of garbage collection in java? (All Company Favorite Question)
4. Latest garbage collector in java?
5. What algorithm is used by the garbage collectors in java? (All Company Favorite Question)
6. Types of memory areas allocated by JVM? (All Company Favorite Question)
7. Ways to make an object eligible for Garbage collection in Java? (All Company Favorite Question)
8. Internal working of JVM and JVM architecture in java? (All Company Favorite Question)

CLICK HERE.  Java project-related interview questions for the Experience

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CLICK HERE.  Spring Interview questions in java click

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CLICK HERE.  Java Coding Interview questions in java click

CLICK HERE.  Hibernate Interview questions in java click

This all is going to ask by an interviewer in Java. So be try to read all questions. If I miss any question then mention in comments

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