Which collection would be the best one to use, if you were working with a Student Information management web application that needs to maintain and search students, stored as instances of a class 'Student'.
You should be able to perform the following:
i) identify a Student by its unique alphanumeric identification number.
ii) Print out the Student in order of their unique identification numbers
A) List
B) ArrayList
C) HashMap
D) TreeMap
E) HashSet
F) Arrays
G) LinkedList
H) Sets
Answer : D (TreeMap)
Explanation :
Option D is correct. Both HashMap and TreeMap enable storing a 'key' and a 'value' combination, where the values and keys can be objects, and the objects are searchable on their keys. However, only TreeMap maintains the natural order of the keys.
source are :
http://www.cafe4java.com/mockexams/scjp/mock3/a1.php
could you please show me why the true answer is D? even the question asks for a collection and map is not a collection.