Is it good practice to pass method in a HashSet?

Question

Is it a good practice to pass method in HashSet like below where i have passed the methods directly inside HashSet?

Set byPrice = new HashSet(getProductsByPriceFilter( lowPrice, highPrice));**

  public Set<Product> filterProducts(BigDecimal lowPrice,
                BigDecimal highPrice, String manufacturer, String category) {

            Set<Product> byPrice = new HashSet<Product>(getProductsByPriceFilter(
                    lowPrice, highPrice));
            Set<Product> byManufacturer = new HashSet<Product>(
                    getProductsByManufacturer(manufacturer));
            Set<Product> byCategory = new HashSet<Product>(
                    getProductsByCategory(category));

            byPrice.retainAll(byManufacturer);
            byPrice.retainAll(byCategory);

            return byPrice;
        }

Answer 1

One thought on this: if your method already returns something that could fill your entire Set - why not have the method return that Set?

Set<Product> byPrice = getProductsByPriceFilter(
                lowPrice, highPrice));

With some

public Set <Product> getProductsByPriceFilter(double low, double high) {

Same then for the other filters.

Or... pass the already filtered set into the next stage. You probably have a loop over all products in getProductsByManufacturer () . If you added the already filtered set as parameter you could reduce this loop to loop over all products that already are in price range and so on.