15.5.1. Map Interface

Try these first

1. 1.

   What does the put method do in a Map?

   Hint

   Think about how you would add an item to a list.

2. 2.

   True or False: A Map can have duplicate keys.

   Hint

   Consider if you can have two identical names in a contact list.

3. 3.

   Which of the following methods adds a key-value pair to a Map?

   • get()
   • put()
   • remove()

   Hint

   Consider which option sounds like it relates to 'adding'.

4. 4.

   True or False: A TreeMap automatically sorts keys.

   • True
   • False

   Hint

   Think about how trees grow: do they follow an order?

5. 5.

   Create a method that counts the number of occurrences of each character in a string. Use a HashMap for this solution.

   Hint

   Think about how you can check if a character already exists in your Map.

6. 6.

   Implement a contact manager using a LinkedHashMap where you can add, find, and update contacts based on unique names.

   Hint

   Consider what happens when you want to look for a name: does order matter?