Dreaming about a career in IT? But let’s be clear in our mind, to have a fantastic career in IT, the hands-on experience and expertise in Java Programming Language is the most essential requirement. Now, you must be wondering that “Why should I learn Java Programming Language?”

Before digging further deeper, let’s gets ourselves educate you about Java.

From website to mobile, electronic appliances to so many servers, the presence of java is inevitable. That’s what keeps Java everyone’s favorite in the world of programming languages. It is a go-to language for millions of students and software developers.

Why learn Java

1. An estimated 90 percent of Fortune 500 companies count on Java language. It’s among the most popular server-side languages for back-end development, and it’s a must on any coder’s resume.

2. Java is also known to be extremely stable and so, many large enterprises have adopted it. If you are looking for a development based job at some large enterprises, Java is the language that you should learn. Big players like IBM and Infosys are in constant need of Java developers.

3. By any chance, if you develop an affinity for Android development then one must be well versed with it. This is the digital era and there are so many businesses which need android Application owing to the fact that there are billions of Android users today. Again this opens up a huge scope for Java developers.

4. Most importantly Java is an open source ‘learning’ language and you don’t need to spend a single penny to work under Java. You can write, develop and execute your own applications absolutely free.

Generally, most of the interviewer tends to start with the core Java concepts before jumping onto more advanced topics. The reason is very simple that they want to ease you and make you feel comfortable and confident.

These questions may range from simple object-oriented principles to most used Java classes such as string or hashmap. These questions are aim to test your foundation, your basic knowledge, and your grip over the programming. 

1. What does “System.out.println ( )” specify?

2. Why String is immutable in java?

3. Why multiple inheritances are not supported in Java?

4. How to detect deadlock and fix it?

5. When a singleton is not singleton in Java?

6. Difference between noclassdefounderror and classnotfoundexception?

7. What happens when you place a return statement or System exit () on and try to hold a block? Will that block be executed?

8. Is it possible to override a static method?

9. What does 1.0 / 0.0 mean? What does it return? Shall it give any exception? Are there are any compile time errors?

10. Does Java in any way support several inheritances?

11. Explain race condition in Java hashmap? 

12. Can we call static method with null object?

13. Mention the situations when you will prefer to use interfaces and when abstract classes.

14. How are the source code files named in Java?

15. Does Java support networking?

16. Does all property of Immutable Object need to be final?

17. How does substring () inside String works?

18. How do you handle error condition while writing a stored procedure or accessing stored procedure from java?


19. What is Singleton? is it better to make the whole method synchronized or only critical section synchronized?


31. Explain the concept of object cloning and how is this used in java?



33.  What will happen if you put return statement or System.exit () on try or catch block? Will finally block execute?


34. What will happen if we put a key object in a HashMap which is already there?


35. If a method throws NullPointerException in the superclass, can we override it with a method which throws RuntimeException?


36. What is the difference between StringBuffer and StringBuilder in Java?


37. How do you create thread-safe Singleton in Java?



40. Is it possible for equals() to return false, even if the contents of two Objects are the same?

41. Why compareTo() should be consistent to equals() method in Java?




Closing Notes

Great!!, finally you made it to the end of the article… Wish you all the best for your Java Programming Interview! We hope now you can crack any tough nut, we have also listed some of the best books for preparing java interview.


Knowledge is of no value unless you put it into practice.