Java Interview Questions (Part 1) – Rookies Series

The article (first in the series) aims to present some tricky interview Java questions that could help you score high in your next Java interviews:


Programming fundamentals


Java Objects


  • Question: What is difference between LinkedList and ArrayList? When would you want to use one and not the other?
  • Question: How come you keep on adding objects in an ArrayList using add method and no exception is ever thrown? Could you think about underlying code?
    Answer: Take a look at the pictures below. The magic happens in the ensureCapacity method where a new arrayList is created, the elements from old arraylist is copied to new one and reference of new arraylist is assigned to member variable (elementData).

    java arraylist add method

    fig: java arraylist add method

    ensureCapacity Method to Handle ArrayList Size1

  • Question: What is difference between a Set and a List?
    Answer: The primary difference is that Set is a collection that consists of no duplicate elements or, in other words, consists of all unique elements.  Read further on the following page:


Exception Handling




Ajitesh Kumar
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Ajitesh Kumar

I have been recently working in the area of Data Science and Machine Learning / Deep Learning. In addition, I am also passionate about various different technologies including programming languages such as Java/JEE, Javascript, Python, R, Julia etc and technologies such as Blockchain, mobile computing, cloud-native technologies, application security, cloud computing platforms, big data etc. I would love to connect with you on Linkedin.
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