How can I use streams with functional interfaces in Java?

How can I use streams with functional interfaces in Java?

You can use streams in Java to process collections of data in a functional style. Functional interfaces like Predicate, Function, and Consumer can be used with streams to filter, map, and perform actions on the data.

Can you give me an example of using a stream with a functional interface?

Sure! Here's a simple example: You can use the filter method with a Predicate to filter a list of integers. For instance:

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
List<Integer> evenNumbers = numbers.stream()
    .filter(n -> n % 2 == 0)
    .collect(Collectors.toList());

This will give you a list of even numbers.

What about using the map function?

Great question! The map function can be used with a Function to transform the elements of a stream. For example:

List<String> names = Arrays.asList("Alice", "Bob", "Charlie");
List<Integer> nameLengths = names.stream()
    .map(String::length)
    .collect(Collectors.toList());

This will give you a list of the lengths of each name.

Are there any performance considerations when using streams?

Yes, while streams can make your code more readable, they can also introduce overhead. It's important to consider the size of the data and the operations being performed. For large datasets, using parallel streams can improve performance, but be cautious of thread safety and order.