The Collectors.toSet() method can be used for collecting all Stream elements into a Set instance.

Learn Java 8 at https://www.javaguides.net/p/java-8.html

Java 8 Collectors.toSet() Example

import java.util.stream.Collectors;
import java.util.Set;
import java.util.List;
import java.util.ArrayList;
class Product {
    int id;
    String name;
    float price;

    public Product(int id, String name, float price) {
        this.id = id;
        this.name = name;
        this.price = price;
    }
}
public class CollectorsExample {
    public static void main(String[] args) {
        List < Product > productsList = new ArrayList < Product > ();
        //Adding Products  
        productsList.add(new Product(1, "HP Laptop", 25000 f));
        productsList.add(new Product(2, "Dell Laptop", 30000 f));
        productsList.add(new Product(3, "Lenevo Laptop", 28000 f));
        productsList.add(new Product(4, "Sony Laptop", 28000 f));
        productsList.add(new Product(5, "Apple Laptop", 90000 f));
        Set < Float > productPriceList =
            productsList.stream()
            .map(x - > x.price) // fetching price  
            .collect(Collectors.toSet()); // collecting as list  
        System.out.println(productPriceList);
    }
}