Java.Collections.How to convert an ArrayList to a HashSet in one line?

✅ To convert an ArrayList to a HashSet in one line, just use the HashSet constructor:

Set<String> set = new HashSet<>(arrayList);

💡 Example:

List<String> arrayList = List.of("apple", "banana", "apple", "cherry");

Set<String> set = new HashSet<>(arrayList); // One-liner conversion

System.out.println(set); // Output: [banana, cherry, apple] (order not guaranteed, duplicates removed)

🧠 Notes:

• ✅ Duplicates are removed automatically.
• ❌ Order is not preserved (because HashSet is unordered).
• If you want to preserve insertion order, you can use:

Set<String> set = new LinkedHashSet<>(arrayList);