15.5. Map Interface and Its Implementations

Try these first

1. 1.

   What is a Map in Java?

   Hint

   Think of examples like dictionaries or address books.

2. 2.

   Name one implementation of the Map interface.

   Hint

   Recall the different types we discussed.

3. 3.

   Which of the following implementations allows null keys?

   • HashMap
   • Hashtable
   • TreeMap

   Hint

   Think about the restrictions for keys.

4. 4.

   True or False: A LinkedHashMap maintains the order of elements.

   • True
   • False

   Hint

   Recall how LinkedHashMap stores elements.

5. 5.

   Design a small phone book application using HashMap, where the name is the key and the phone number is the value. Show how you would add and retrieve entries.

   Hint

   Think about defining your map and using put/get methods.

6. 6.

   You are required to create a voting system that keeps track of the number of votes each candidate receives. Use a TreeMap where the candidate names are keys and the votes are values. How would you implement the updating mechanism?

   Hint

   Reflect on how you'd maintain order and update the values.