Java HashSet Examples

This page contains source code examples of the HashSet class in Java. On this page, we will learn everything about the Java HashSet class with source code examples.

Following are few key points to note about HashSet in Java -
  • HashSet cannot contain duplicate values.
  • HashSet allows null value.
  • HashSet is an unordered collection. It does not maintain the order in which the elements are inserted.
  • HashSet internally uses a HashMap to store its elements.
  • HashSet is not thread-safe. If multiple threads try to modify a HashSet at the same time, then the final outcome is not-deterministic. You must explicitly synchronize concurrent access to a HashSet in a multi-threaded environment.

Java HashSet Class Examples