Java Interview Questions (Part 1) – Rookies Series

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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

  

Collections
  • Question: What is difference between LinkedList and ArrayList? When would you want to use one and not the other?
    Answer: http://javarevisited.blogspot.in/2012/02/difference-between-linkedlist-vs.html
  • 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:
    http://stackoverflow.com/questions/1035008/what-is-the-difference-between-set-and-list

  

Exception Handling

  

Others

 

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Ajitesh Kumar

Ajitesh Kumar

Ajitesh is passionate about various different technologies including programming languages such as Java/JEE, Javascript, PHP, C/C++, mobile programming languages etc, and, computing fundamentals related with cloud-native technologies, application security, cloud computing platforms, mobile apps, big data etc.

He has also authored the book, Building Web Apps with Spring 5 and Angular.
Ajitesh Kumar

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