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Junior Java Interview Questions

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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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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

Company for some reason makes a strong accent on concurrency initially. I was asked to create a load balancer with the production like code. You won't be given any requirements initially but only to implement the register method. Tried to clarify all the requirements ( target groups, healthchecks etc. ) From the interviwer answers I realized I shouldn't clarify requiments at this point. More requirements will be added added like capacity limitation and uniqueness check. why do you prefer register(String url) over register(URL url)? in what case the array list append won't be constant time? why it's not ready for prod ( concurrency ) what problems do you see? what's the simplest was to fix it? Didn't receive any feedback so it's hard to tell what was expected.
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Senior Java Developer

Interviewed at Revolut

4★
May 26, 2025

Company for some reason makes a strong accent on concurrency initially. I was asked to create a load balancer with the production like code. You won't be given any requirements initially but only to implement the register method. Tried to clarify all the requirements ( target groups, healthchecks etc. ) From the interviwer answers I realized I shouldn't clarify requiments at this point. More requirements will be added added like capacity limitation and uniqueness check. why do you prefer register(String url) over register(URL url)? in what case the array list append won't be constant time? why it's not ready for prod ( concurrency ) what problems do you see? what's the simplest was to fix it? Didn't receive any feedback so it's hard to tell what was expected.

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