15.3.1. Set Interface

Try these first

1. 1.

   What does the Set Interface prevent in a collection?

   Hint

   Consider the unique nature of elements.

2. 2.

   What implementation of Set maintains the order of insertion?

   Hint

   Think about how elements are added.

3. 3.

   What does the Set interface guarantee?

   • Allows duplicates
   • Does not allow duplicates
   • Stores elements in order

   Hint

   Think about what makes a Set different from a List.

4. 4.

   True or False: A LinkedHashSet preserves the insertion order.

   • True
   • False

   Hint

   Recall how elements are organized.

5. 5.

   You are building a contact application that must ensure that no duplicate emails exist. Which Set implementation would you choose and why?

   Hint

   Think about access speed versus order preservation.

6. 6.

   Write a Java method that accepts a List of integers and returns a Set containing only the unique integers.

   Hint

   Play with the HashSet constructor that takes a collection.