Core Java Interview Questions

92 core java interview questions shared by candidates

1st round was an online written test of 55 mins , which was divided in two sections Aptitude and Java Aptitude had 25 question to be completed within 25 mins (somewhat CAT level aptitude, critical reasoning, relationship questions, exponential series, ratio, permutation and combination) Java section had 30 questions to be completed in 30 mins (multi threading,inheritance,static,final,exception propagation related questions)
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Core Java Consultant

Interviewed at BT Group

3.7
Oct 9, 2015

1st round was an online written test of 55 mins , which was divided in two sections Aptitude and Java Aptitude had 25 question to be completed within 25 mins (somewhat CAT level aptitude, critical reasoning, relationship questions, exponential series, ratio, permutation and combination) Java section had 30 questions to be completed in 30 mins (multi threading,inheritance,static,final,exception propagation related questions)

While the interview questions were basic, these were not the answers you might be remembering or having only one correct answer. HTTP Codes, RestAPI design, database query on tree and recursion, Code analysis on switch case, etc and other past experience questions.
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Software Engineer Core Java

Interviewed at Syndigo

3.8
Jun 27, 2023

While the interview questions were basic, these were not the answers you might be remembering or having only one correct answer. HTTP Codes, RestAPI design, database query on tree and recursion, Code analysis on switch case, etc and other past experience questions.

1)singleton to get database connection . 2)bubble sort alogoritjm. 3)all possible purmutation of a string . 4)Deadloack in java . 5)non repeated characters in a string 6)duplicates in a string ,array independent of the type of arrya and string
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Core Java, Webservices

Interviewed at HARMAN

3.8
Jul 21, 2019

1)singleton to get database connection . 2)bubble sort alogoritjm. 3)all possible purmutation of a string . 4)Deadloack in java . 5)non repeated characters in a string 6)duplicates in a string ,array independent of the type of arrya and string

1. Tell me something about you? 2. Tell some your skills ? 3. Explain internal working of Treemap? 4. following above question , What is self balanced tree ,& Binery tree? explain how it is work and how it is used in TreeMap. 5.Why we need Callable interface? tell something about Future? 6. where do you used the multithreading in your project? why do you used it? 2nd round(Manager) 1. we have map ,and we have put these values , how many element would be there in map? 2.How you can access service from component?(angular2+) 3. how you can call any api from service?(angular2+) 4. what is payload? 5. Full form of JSON and Rest? 6. give some example of JSON? 7. IS it important to put all key and value inside "" this mark?(JSON) 8. Do you remeber any jar that convert the given object into Json? 9.how you can retrieve back the key of given value from map if you forget the key? 10. what collection will you use to cache all the data of Employee table? 11. how you will create REST API in Spring rest/Spring boot? 12. what happen if two different developer use the same END point url while creating the REST api? 13. sql - suppose you have employee table , any you have to find out how many male and female are working. than write sql to find it. 14. sql. now find out male and female count based on city that working on company?
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Core Java Developer

Interviewed at UBS

3.7
Aug 20, 2018

1. Tell me something about you? 2. Tell some your skills ? 3. Explain internal working of Treemap? 4. following above question , What is self balanced tree ,& Binery tree? explain how it is work and how it is used in TreeMap. 5.Why we need Callable interface? tell something about Future? 6. where do you used the multithreading in your project? why do you used it? 2nd round(Manager) 1. we have map ,and we have put these values , how many element would be there in map? 2.How you can access service from component?(angular2+) 3. how you can call any api from service?(angular2+) 4. what is payload? 5. Full form of JSON and Rest? 6. give some example of JSON? 7. IS it important to put all key and value inside "" this mark?(JSON) 8. Do you remeber any jar that convert the given object into Json? 9.how you can retrieve back the key of given value from map if you forget the key? 10. what collection will you use to cache all the data of Employee table? 11. how you will create REST API in Spring rest/Spring boot? 12. what happen if two different developer use the same END point url while creating the REST api? 13. sql - suppose you have employee table , any you have to find out how many male and female are working. than write sql to find it. 14. sql. now find out male and female count based on city that working on company?

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