public List<ProductHierarchy> createHierarchy(List<Product> allProducts, Product p) { List<ProductHierarchy> SubHierarchy = new ArrayList<ProductHierarchy>(); for (Product prod : allProducts) { if (prod.getParentID() == this.product.getID()) { SubHierarchy.add(new ProductHierarchy(allProducts, prod)); } } return SubHierarchy; }