Java-Collections

Which of the following is a part of the Java Collections Framework?

• ArrayList

• Array

• int[]

• String

Which collection does not allow duplicate elements?

• List

• Set

• Map

• All of the above

Which collection class is synchronized?

• HashSet

• TreeSet

• Hashtable

• HashMap

Which of these is not a method in the Collection interface?

• add()

• get()

• remove()

• size()

What is the output of the following code?

ArrayList<String> list = new ArrayList<>();

list.add("Java");

list.add("Python");

System.out.println(list.remove(0));

• Java

• Python

• true

• Compilation error

Which of the following is incorrect statement about the Hastable class?

• Hashtable class implements Map interface.

• Hashtable class extends the Dictionary class.

• Hashtable class implements Cloneable interface.

• Hashtable class extends Properties class.

Which one is the correct way to iterate over elements in an ArrayList?

• for (int i = 0; i < list.size(); i++)

• for (int i : list)

• for (Object obj : list)

• for (Iterator it = list.iterator(); it.hasNext();)

Which of the following statement is incorrect about Deque interface in Java?

• It is typically pronounced as "deck".

• It stands for doubly-ended queue.

• It is mostly used to implement some algorithms and data structures.

• It can either be used as a queue(FIFO) or as a stack(LIFO).

Suppose you are working in a Java project. You have a requirement where you need a dynamic or resizable array-like data structure that can permit you to add, remove, and access elements at a specific index efficiently. It should also automatically adjust its size when the elements are added or removed. Which of the following class will you use to satisfy your requirement?

• Vector

• LinkedList

• ArrayList

• HashMap

Which method is used to add an element to the end of an ArrayList?

• addLast()

• addEnd()

• add()

• append()