Java MCQ – Collections – Part 4

This collection of Java Multiple Choice Questions and Answers (MCQs): Quizzes & Practice Tests with Answer focuses on “Java Collections”.
 

1. HashTable internally uses the following technique for inserting and retrieving elements?

A Serialization

B Typecast

C Randomizing

D Hash

Answer  

2. Arraylist, Linkedlist and Vector are __________

A interfaces

B enums

C classes

D None of the above

Answer  

3. Which of the following does not allow insertion of duplicates elements?

A Treeset

B Vector

C Linkedlist

D Copyonwritearraylist

Answer  

4. Which gives better performance for inserting and deleting in the middle of the list?

A Vector

B ArrayList

C LinkedList

D All the answers are true

Answer  

5. What is the output of the following code?

import java.util.*;
	
public class Main 
{
	public static void main(String args[]) 
	{
		LinkedList<Integer> lang = new LinkedList<Integer>();
		lang.add(8);
		lang.add(2);
		lang.add(1);
		lang.add(6);

		Iterator it = lang.iterator();
		Collections.reverse(lang);
		Collections.sort(lang);
		while(it.hasNext())
			System.out.print(it.next() + " ");
	}
}

A 6 1 2 8

B 1 2 6 8

C 8 6 2 1

D 8 2 1 6

Answer  

6. Which of these variables is a static variable defined in Collections?

A EMPTY_LIST

B EMPTY_SET

C EMPTY_MAP

D All the answers are true

Answer  

7. After resizing, the size of the vector is increased by ___

A 200%

B 100%

C 50%

D None of the above

Answer  

8. After resizing, the size of the ArrayList is increased by ___

A 200%

B 100%

C 50%

D All the answers are true

Answer  

9. Deque and Queue inherit from _____

A Collection

B AbstractList

C AbstractCollection

D List

Answer  

10. An unordered array has a search time complexity of ____

A O(log n)

B O(n)

C O(n + 1)

D O(1)

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