26/Sep/2021 | 5 minutes to read
java
Here is a List of essential Java Interview Questions and Answers for Freshers and mid level of Experienced Professionals. All answers for these Java questions are explained in a simple and easiest way. These basic, advanced and latest Java questions will help you to clear your next Job interview.
These interview questions are targeted for Java Developers. You must know the answers of these frequently asked Java interview questions to clear the interview. We have separate document for Core Java, Java coding, Java collections and Java data structures interview questions.
1. Why is Java not a pure object-oriented language?
2. Why is String immutable in Java?
When we can not update or mutate the state of an object by any means then it's known as Immutable Object. When you assign a string object
to a variable then it becomes immutable as you can not change its state.
If you declare two string variables "a" and "b" holding the same values "Hello Testing" then both
variables point to the same object in memory or string pool. If you declare a third variable which also stores the same value "Hello Testing" then JVM will reference
an existing object created for variable "a" instead of creating a new object in memory. So in this case, the state of an object remains unchanged,
Hence String is immutable in Java.
String immutability provides some benefits as below.
2. What is the role of String Pool in Java?
3. Explain Instance variables and local variables in Java.
4. What do you understand from Association and Aggregation?
5. Differentiate Abstract class and Interface.
6. Explain Synchronized block in Java.
7. What is Singleton class?
8. Can we have singleton without private constructor?
9. What is the Executor interface?
10. Explain Thread, Process
11. Explain Docker Deployment Process.
12. What is the difference between Permgen and Metaspace in Java?
For more visit Permgen vs Metaspace.
13. Explain Stack Memory in Java. How does it work?
14. Explain Heap Space and How it works?
15. How to increase Heap size for a Java Program?
16. Explain the deadlock situation.
17. What is the need for custom exceptions in Java?
18. How does Serialization and De-serialization work in Java?
19. Explain Thread Context Switching Problems in Java.
20. How will you create an executable JAR with dependencies using Maven?
1. How much will you rate yourself in Java?
When you attend an interview, Interviewer may ask you to rate yourself in a specific Technology like Java, So It's depend on your knowledge and work experience in Java. The interviewer expects a realistic self-evaluation aligned with your qualifications.
2. What challenges did you face while working on Java?
The challenges faced while working on Java projects are highly dependent on one's specific work experience and the technology involved. You should explain any relevant challenges you encountered related to Java during your previous projects.
3. What was your role in the last Project related to Java?
This question is commonly asked in interviews to understand your specific responsibilities and the functionalities you implemented using Java in your previous projects. Your answer should highlight your role, the tasks you were assigned, and the Java features or techniques you utilized to accomplish those tasks.
4. How much experience do you have in Java?
Here you can tell about your overall work experience on Java.
5. Have you done any Java Certification or Training?
Whether a candidate has completed any Java certification or training is optional. While certifications and training are not essential requirements, they can be advantageous to have.
We have covered some frequently asked Java Interview Questions and Answers to help you for your Interview. All these Essential Java Interview Questions are targeted for mid level of experienced Professionals and freshers.
While attending any Java Interview if you face any difficulty to answer any question please write to us at info@qfles.com. Our IT Expert team will find the best answer and will update on the portal. In case we find any new Java questions, we will update the same here.