Multiple Choice Question

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Submitted by c-admin on Wed, 05/29/2019 - 05:28

QID:

233

Type:

Multiple Choice Question

Category:

Java Programmer I

Tags:

ArrayList

Question:

Identify the correct statements about ArrayList?

Select 3 options

A. Standard JDK provides no subclasses of ArrayList.
B. You cannot store primitives in an ArrayList.
C. It allows constant time access to all its elements.
D. ArrayList cannot resize dynamically if you add more number of elements than its capacity.
E. An ArrayList is backed by an array.

Answer and Explanation (Click to expand)

Answer:

B - This is true because only Objects can be stored in it.

C - This is true because it implements java.util.RandomAccess interface, which is a marker interface that signifies that you can directly access any element of this collection. This also implies that it takes the same amount of time to access any element. (Compare that with a LinkedList, which takes more time to access the last element than the first element.)

E - This is true. The elements are actually stored in an array and that is why is it called an ArrayList. (The expression "backed by an array" means that the implementation of ArrayList actually uses an array to store elements.)

Explanation:

ArrayList is a subclass of AbstractList.
java.lang.Object
- java.util.AbstractCollection<E>
- java.util.AbstractList<E>
- java.util.ArrayList<E>
All Implemented Interfaces:
Serializable, Cloneable, Iterable<E>, Collection<E>, List<E>, RandomAccess
Direct Known Subclasses:
AttributeList, RoleList, RoleUnresolvedList

Q&A Set:

Set 31

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