Collectors.grouping

Collectors.groupingBy is a static method in the java.util.stream.Collectors class that performs grouping operations on the elements of a stream. It allows you to group the elements based on a specific criterion or property.

Here's an example of how to use Collectors.groupingBy:

Suppose we have a list of Person objects, and we want to group them by their age:

List<Person> people = Arrays.asList(
    new Person("John", 25),
    new Person("Alice", 30),
    new Person("Bob", 25),
    new Person("Jane", 30)
);

Map<Integer, List<Person>> peopleByAge = people.stream()
    .collect(Collectors.groupingBy(Person::getAge));

In this example, we use the Person::getAge method reference as the grouping criterion. The resulting map, `peopleByAge`, will have the age as the key and a list of people with that age as the value.

Hope that helps! Let me know if you have any more questions.