Core Java Developer Interview Questions

90 core java developer interview questions shared by candidates

1st round they give a 2 test 1st one is Aptitude test(multi-threading,collection,etc) 2nd is logical test (no Option) 2nd round they ask to write the code of Q1. Anagram two String without using Array.sort method. Q2. Armstrong number Q3. producer-consumer problem using multi-threading in java Q4. Star pattern in java Q5. Performer in Array without using ArrayList Method like (add,delete,remove).you have to write the own method to add,delete&remove in array 3rd round they ask logical Question base on code that you write in 2nd round 4th round they ask you about your self and family
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Core Java Developer

Interviewed at Xalted Information Systems

3.7
Dec 11, 2019

1st round they give a 2 test 1st one is Aptitude test(multi-threading,collection,etc) 2nd is logical test (no Option) 2nd round they ask to write the code of Q1. Anagram two String without using Array.sort method. Q2. Armstrong number Q3. producer-consumer problem using multi-threading in java Q4. Star pattern in java Q5. Performer in Array without using ArrayList Method like (add,delete,remove).you have to write the own method to add,delete&remove in array 3rd round they ask logical Question base on code that you write in 2nd round 4th round they ask you about your self and family

1. what is java polymorphism - how java implements polymorphism? 2. purpose of volatile keyword 3. can top level class be declared static? 4. when is object.finalise method, when is it called? 5. Can we syncronise the static method 6. Can we invoke non static method from static method on same class 7. Producer and consumer pattern explain?? 8. Which design pattern u used in ur projects? 9. Describe heirarchy of exception class 10. Java collection api - describe a few? 11. Describe transient variable 12. Describe final keyword 13. Multithreading - how to create multiple thread, describe how to start new thread 14. Difference between runnable and callable 15. Difference between treemap and hashmap? 16. String, string builder and string buffer differences 17. Java io apis which u used -? 18. Singleton pattern - explain 19. How do you make class singleton.
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Senior Core Java Developer

Interviewed at Citi

3.6
Jun 25, 2016

1. what is java polymorphism - how java implements polymorphism? 2. purpose of volatile keyword 3. can top level class be declared static? 4. when is object.finalise method, when is it called? 5. Can we syncronise the static method 6. Can we invoke non static method from static method on same class 7. Producer and consumer pattern explain?? 8. Which design pattern u used in ur projects? 9. Describe heirarchy of exception class 10. Java collection api - describe a few? 11. Describe transient variable 12. Describe final keyword 13. Multithreading - how to create multiple thread, describe how to start new thread 14. Difference between runnable and callable 15. Difference between treemap and hashmap? 16. String, string builder and string buffer differences 17. Java io apis which u used -? 18. Singleton pattern - explain 19. How do you make class singleton.

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