Java Sets

A Set does not allow duplicate elements and has different behaviors based on its implementation.

Common Implementations

Implementation	Features	Best For
HashSet<E>	No duplicates, no order	Fast lookups
LinkedHashSet<E>	Maintains insertion order	Iteration in order of insertion
TreeSet<E>	Sorted order (uses Comparable or Comparator)	Sorted data retrieval

Example: Using HashSet

import java.util.HashSet;
import java.util.Set;
 
public class SetExample {
    public static void main(String[] args) {
        Set<Integer> numbers = new HashSet<>();
        numbers.add(10);
        numbers.add(20);
        numbers.add(10);  // Ignored (no duplicates allowed)
 
        System.out.println(numbers);  // Output: [10, 20] (order may vary)
    }
}