Java : Functional interfaces and Lamda expression

I'll show you how you can check a condition and return a boolean value. The java API includes 3 functional interfaces commonly used:

1. Predicate<T> 
2. Consumer<T>
3. Function<T, R>

The Predicate tests the T object and returns a boolean value. The Consumer accepts an operation on T but does not return a value. The Function performs an operation on T and returns an R object.

The static method below uses the Predicate interface to specify the condition:

	public static List<Product> filterProducts(List<Product> products,
	Predicate<Product> predicate){
	List<Product> list = new ArrayList<>();
	for(Product p : products){
	if(predicate.test(p)){
	list.add(p);
	}
	}
	return list;
	}

view raw filter_list_java hosted with ❤ by GitHub

You can use this method like this:

	List<Product> productsWithCASNumber = filterProducts(products,
	p -> p.getCASNumber() != null);

view raw filter_list_java_used hosted with ❤ by GitHub

Thanks