15.5.2. Implementations

Try these first

1. 1.

   What is the primary reason for using a Map in Java?

   Hint

   Think about how we access stored data.

2. 2.

   Can a HashMap contain null values?

   Hint

   Consider what kind of data structures allow nulls.

3. 3.

   Which of the following implementations of Map does not allow null keys?

   • HashMap
   • LinkedHashMap
   • Hashtable

   Hint

   Think about which implementation is synchronized.

4. 4.

   True or False: TreeMap maintains the order of elements based on their natural ordering.

   • True
   • False

   Hint

   Reflect on how elements are stored in an ordered fashion.

5. 5.

   You are building a contact management application. Which Map implementation would you choose and why?

   Hint

   Think about how contacts are accessed.

6. 6.

   Data from a large data set must be stored in a sorted manner for quick retrieval. Which implementation should be chosen?

   Hint

   Consider how data will be organized and accessed.