Java Engineer Interview Questions

27,775 java engineer interview questions shared by candidates

1. OOps concepts with examples. 2. Write a java program to find the first duplicate in an array. 3. Write a java program to print the occurrences of each character. 4. Explain the approach to print middle element in a linked list. 5. Given a string str = "hfjsk6485lop", sort the string and print the characters first and print digits last. 6. Find a missing a element in an array. 7. Collection framework hierarchy. 8. Difference between abstract class and interface. 9. What is association and aggregation . 10. some code snippets to answer. 11. Internal working of a hash map, what is the case if two elements hash code is same. 12. What are the challenges that you faced in your projects how you have handled them. 13. Difference between string, stringBuffer, String builder. 14. Difference between final, finally, finalize. 15. Difference between Exception and Error. 16. Can you throw custom exception with Error Object. 17. Exception handling hierarchy.
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Software Engineer - Java Developer

Interviewed at Siemens

4
Jul 9, 2021

1. OOps concepts with examples. 2. Write a java program to find the first duplicate in an array. 3. Write a java program to print the occurrences of each character. 4. Explain the approach to print middle element in a linked list. 5. Given a string str = "hfjsk6485lop", sort the string and print the characters first and print digits last. 6. Find a missing a element in an array. 7. Collection framework hierarchy. 8. Difference between abstract class and interface. 9. What is association and aggregation . 10. some code snippets to answer. 11. Internal working of a hash map, what is the case if two elements hash code is same. 12. What are the challenges that you faced in your projects how you have handled them. 13. Difference between string, stringBuffer, String builder. 14. Difference between final, finally, finalize. 15. Difference between Exception and Error. 16. Can you throw custom exception with Error Object. 17. Exception handling hierarchy.

Q1) Write simple java code for ,whether given string have character "i" ,using stream API only. Ex: If input is "hello" word, output will be false, as the word doesn't have letter "i". Q2) what is volatile keyword is used for? Q3)explain oops concepts? Q4)why java doesn't support multiple inheritance, what happens if we try to implement? can you explain with some example ? Q5)what is multi threading? Do you know about executor ? Q6)what is REST? Q7)When we are opening a google page, which type of request it is?GET or POST or other requests? Q8)how Requests are mapping with servlets in SPRING MVC? can you explain? Q9)Why spring boot s required,when we have many spring components already?Advanatages of Springboot? Q10)what is Springboot profiling concept? Q11)What are the things you write or configure,in your spring boot application,related to tomcat? Q12)what collections you used in your project?explain How hashmap buckets internally works? Q13)DIfference between HTTP and HTTPS? Q14)What type of errorcodes you get genearlly, when you access a REST webservice using browser? etc
avatar

Java Developer

Interviewed at Synechron

4.1
Jun 7, 2022

Q1) Write simple java code for ,whether given string have character "i" ,using stream API only. Ex: If input is "hello" word, output will be false, as the word doesn't have letter "i". Q2) what is volatile keyword is used for? Q3)explain oops concepts? Q4)why java doesn't support multiple inheritance, what happens if we try to implement? can you explain with some example ? Q5)what is multi threading? Do you know about executor ? Q6)what is REST? Q7)When we are opening a google page, which type of request it is?GET or POST or other requests? Q8)how Requests are mapping with servlets in SPRING MVC? can you explain? Q9)Why spring boot s required,when we have many spring components already?Advanatages of Springboot? Q10)what is Springboot profiling concept? Q11)What are the things you write or configure,in your spring boot application,related to tomcat? Q12)what collections you used in your project?explain How hashmap buckets internally works? Q13)DIfference between HTTP and HTTPS? Q14)What type of errorcodes you get genearlly, when you access a REST webservice using browser? etc

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