SAP Labs Java interview

Cannot have instance variables, constructors and can have only public and none (aka package) visibility.

Question : When to use an abstract class?
Answer : In case where you want to use implementation inheritance then it is usually provided by an abstract base class. Abstract classes are excellent candidates inside of application frameworks. Abstract classes let you define some default behaviour and force subclasses to provide any specific behaviour.

Question : When to use Interfaces?
Answer : When the client wants to only deal with a type and does not care about the actual implementation then we should use interfaces. As i said earlier, abstract classes should be used if a consistent behaviour is required across object hierarchy or for partial implementation.

Question : Explain the Java collection framework.
Answer : explained...

Question : Difference between ArrayList & Linked List?
Answer : An ArrayList is a List implementation backed by a Java array, similar to the Vector class. As the number of elements in the collection increases, the internal array grows to fit them. If there are lots of growth periods, performance degrades as the old array needs to be copied into the new array. However, random access is very quick as it uses an array index to access.
With a LinkedList, the List implementation is backed by a doubly linked list data structure, allowing easy inserts/deletions anywhere in the structure, but really slow random accesses as the access must start at an end to get to the specific position.

Question : When to use LinkedList & When to use Array List?.
Answer : If you want to add and remove the elements frequently then use LinkedList , for simple retrieve use ArrayList because for simple retrieval ArrayList is faster than LinkedList.

Question : What is synchronization?
Answer : Syncronization is the process of controling the access of multiple threads to a shared resource.

Question : Did you implement synchronization in your project?
Answer : No we did not use threads so no synchronizattion.

Question : What are the likes & dislikes of the present company?
Answer : ....

Question : What you know about SAPLabs?
Answer : .....

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