Interview questions on Collections in java for experienced

 Part 12

Interview questions on Collections in java for experienced covered in this post:

    What is the difference between Array and ArrayList?

	Array	ArrayList
1.	An array is a fixed length of data structure. It's not dynamic.	ArrayList is not a fixed type of data structure Arraylist is dynamic.
2.	An array can store only homogeneous objects.	ArrayList can store homogeneous as well as heterogeneous objects.
3.	While declaring an array it is mandatory to declare the size of an array.	While declaring an ArrayList it is not mandatory to declare the size of ArrayList.
4.	You cannot add a new element once the array gets full.	You can easily add a new element once the ArrayList gets full.
5.	An array is not a part of the collection framework.	ArrayList is a part of the Collection framework.
6.	An array can be single or multidimensional.	ArrayList cannot be multidimensional.
7.	For iterating array, we can use while loop, for loop, for each loop.	For iterating ArrayList, we can use an iterator.
8.	Arrays are by default type-safe.	ArrayList is not by-default type-safe. We have to make it type-safe explicitly.
9.	Performance of array is best than ArrayList.	The performance of ArrayList is a little low as compared to an array.

 

    What is the difference between ArrayList and Vector?

	ArrayList	Vector
1.	ArrayList is not thread-safe.	Vector is thread-safe.
2.	Methods of ArrayList are not thread-safe.	All methods of Vector are thread-safe.
3.	The performance of ArrayList is best than Vector.	The performance of Vector is low as compared to ArrayList.
4.	ArrayList is not a legacy class. Introduced in Java 1.2	Vector is a legacy class introduced in 1.0

 

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    What is the difference between ArrayList and LinkedList?

	ArrayList	LinkedList
1.	ArrayList is an index base collection.	LinkedList is a node base collection.
2.	ArrayList implements RandomAccess Interface.	LinkedList doesn’t implement the RandomAccess interface.
3.	ArrayList elements are stored on consecutive memory.	LinkedList elements are not stored on consecutive memory.
4.	There is no singly or doubly concept for ArrayList. Each ArrayList has only one index.	LinkedList can be Singly LinkedList or Doubly LinkedList.
5.	ArrayList is the best option if you want to perform searching, sorting and retrieval operations.	LinkedList is the best option if you want to perform insertion, deletion operations in between of LinkedList.

  

    What is the difference between List and Set?

	List	Set
1.	Duplicate elements are allowed in the list.	Duplicates are strictly not allowed.
2.	Insertion order of elements are preserved.	Insertion order of elements are not preserved.
3.	Implementation classes are as Follows. 1.       ArrayList 2.       LinkedList 3.       Vector 4.       Queue	Implementation classes are as Follows. 1.       HashSet 2.       LinkedHashSet 3.       TreeSet 4.       Queue

 

    What is the difference between Stack and Queue?

	Stack	Queue
1.	The stack data structure is based on LIFO (Last In First Out) principle.	The queue data structure is based on FIFO (First In First Out) principle.
2.	Stack has only one pointer points to elements which is always point on top.	The queue has two pointers, Front Pointer which is pointing to the first element and the rear pointer points to the last element.
3.	Insertion operation is called Push.	Insertion operation is called Enqueue.
4.	The deletion operation is called Pop.	The deletion operation is called Deque.
5.	Insertion and deletion in stacks take place only from one place called Top.	Insertion operation takes place at the rear of the queue and deletion takes place at the front of the queue.

• Java interview questions and answers all MNC - Click here

• Basic core java interview questions and answers for freshers - Click here

• Core java interview questions for 3 years experience - Click here

• Core java interview questions and answers for 3-5 years exp - Click here

• Core java interview questions and Answers for 5 - 7 Years exp - Click here

• Basic Java Interview Questions and Answers - Click here

• Java interview questions and answers on oops - Click here

• Java interview questions and answers on Strings - Click here

• Java interview questions on exception handling - Click here

• Interview questions on multithreading in java for experienced - Click here

• Interview questions on serialization in java for experienced - Click here

• Interview questions on inner class in java for experienced - Click here

• Interview questions on Collections in java for experienced - Click here

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