HashSet

Pros

• Holding pieces of data
• Great for checking to see if something exists
• Really fast for checking if something exists
• it's constant time to add something to set, so they're really fast
• It's like a hashmap except it only has values.

Cons

• An unordered collection of data

Example

See Code Fellows 401 Java lecture notes

... for use of a HashSet to check for specific words in a text document, specifically in Alice in Wonderland: https://github.com/codefellows/seattle-java-401d6/blob/master/class-03/alice/src/main/java/alice/App.java