How can I use the Stream API to filter a list in Java 8?

How can I use the Stream API to filter a list in Java 8?

You can use the filter method of the Stream API to filter elements based on a condition. For example, if you have a list of integers and want to filter out even numbers, you can do it like this:

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

What if I want to filter a list of objects instead?

You can still use the filter method. For instance, if you have a list of Person objects and want to filter by age, you can do:

List<Person> people = ...;
List<Person> adults = people.stream()
                            .filter(p -> p.getAge() >= 18)
                            .collect(Collectors.toList());

Can I chain multiple filters together?

Yes, you can chain multiple filter calls. For example:

List<Person> filtered = people.stream()
                               .filter(p -> p.getAge() >= 18)
                               .filter(p -> p.getName().startsWith("A"))
                               .collect(Collectors.toList());