java - Stream.reduce(Float,BinaryOperator) BinaryOperator 指的是哪个功能接口(interface)方法？

Question

例如，

List<Product> productsList = new ArrayList<Product>();  
productsList.add(new Product(1,"HP Laptop",25000f));  
productsList.add(new Product(2,"Dell Laptop",30000f));  
productsList.add(new Product(3,"Lenevo Laptop",28000f));  
productsList.add(new Product(4,"Sony Laptop",28000f));  
productsList.add(new Product(5,"Apple Laptop",90000f));  

Float totalPrice = productsList.stream()  
                               .map(product->product.price)  
                               .reduce(0.0f,(sum, price)->sum+price);   
System.out.println(totalPrice); 

这里(sum, price)->sum+price指的是哪个功能接口(interface)？

Answer 1

因为你提到了“功能接口(interface)方法”:reduce实际上是在调用 apply of BiFunction (BinaryOperator 从中延伸)。