ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

10 advanced Java Concurrency Interview question answers for Senior Experienced dev

Updated on August 17, 2012

Java Concurrency Interview Questions and Answers

Java Concurrency is favorite topic in various Java interviews. Most of the questions on multi-threading are asked from Java Concurrency API. In this article we will see some advanced concurrency and threading interview question which is mostly asked at senior and experience level programmers in Java interviews. It is assumed that you have basic knowledge of What is thread in java, How thread works and you are familiar with concept of wait and notify in Java which is used for inter-thread communication. you can also look 10 Java tricky question as I have covered some thread related question and answers there as well.

Let's see these advanced Java Concurrency Interview questions, I don't know answers for all questions and I will give answers which I know but most of the answers can be found by doing Google as well.

Java Concurrency and thread Questions answers

1) What is difference between CountDownLatch and CyclicBarrier in Java?

This is the most popular concurrency Questions, almost always appear in Java concurrency and threading interviews. main difference between CountDownLatch and CyclicBarrier is that, you cannot reuse CountDownLatch but you can reuse CyclicBarrier once its finished and barrier is broken. this is in fact a tricky concurrency question because Java programmer some time confuse between CountDownLatch and CyclicBarrier.

2) What is ReentrantLock ? What is advantage of using Lock API in Java?

This is another advanced Concurrency Questions for java programmer. Reentrant lock is an implementation of Lock interface which is an alternative of synchronized keyword in Java.

3) What is difference between ReadWriteLock and ReentrantLock in Java?

Both are Lock implementation, I guess ReadWriteLock provides two separate locks for reading and writing operation which can effectively used to increase concurrency level just like Java did with ConcurrentHashMap. You can also check google for answer of this Java concurrency question.

4) What is difference between HashMap and ConcurrentHashMap in Java?

This is rather simple concurrency interview question. HashMap is not thread-safe while ConcurrentHashMap is a thread-safe class and can be used as an alternative of hashtable in Java.

5) What is difference between fail-fast and fail-safe iterator in Java?

One of my favorite Java concurrency interview question which is related to Collection classes. Fail-fast Iterators are those which fails by throwing ConcurrentModificationException once they detect any structural change in Iterator once iteration begins. while fail-safe Iterator doesn't throw ConcurrentModificationException. See fail-safe vs fail-fast Iterator in Java for more details.

6) What is difference between CopyOnWriteArrayList and ArrayList in Java?

This Java concurrency interview questions is again based on Collection and similar to earlier question difference between HashMap and ConcurrentHashMap, like HashMap, ArrayList are not thread safe and CopyOnWriteArrayList is a thread-safe Concurrent Collection and can be used as an alternative of Vector class in Java.

7) What is Thread Pool ? Why should you use Thread Pool in Java?

8) What is difference between submit() and execute() in Java?

9) What is difference between Executor and Executors in Java?

10) What is BlockingQueue in Java? How it is difference to Other collection classes in Java.

These are some advanced Core Java concurrency question, if you have more than 5 or 6 years experience, it is expected from you to know answers of these Concurrency Questions and it is must to do well in Java interviews.


    0 of 8192 characters used
    Post Comment

    No comments yet.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)