Need a clean way to remove duplicate items from an ArrayList in Java? In this video I walk you through two simple, effective ways to de-duplicate a list of strings (I use a sample list called "cars" with intentionally repeated values so you can see the problem clearly). First, I show the classic HashSet approach. Since a Set can’t contain duplicates, it’s perfect for quickly turning a messy list into a unique collection—just make sure you import the required classes, clear the original ArrayList, and then add everything back with addAll. Then I cover my more modern favorite if you’re on Java 8 or newer: Java Streams. This one is elegant and can be done in basically a one-liner. I stream the list, call distinct() to filter duplicates, and then collect the results back into a new List using Collectors.toList() (don’t forget the stream Collectors import). Both methods give the same output: a clean list with no duplicates—HashSet is easy and classic, while streams are concise and readable.