What is the procedure for streamlining a lambda expression that involves counting?

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The procedure for streamlining a lambda expression that involves counting is as follows:

1. Identify the collection over which you need to count.

2. Use the Stream API's filter() method to filter out the elements that you don't need to count.

3. Use the count() method to count the remaining elements in the collection.

4. Combine the above steps into a single lambda expression using method chaining.

For example, let's say you have a list of Person objects and you want to count the number of people who are over 18 years old. Here's how you can streamline the lambda expression for this scenario:

List<Person> people = ... // initialize the list of people

long count = people.stream()
                   .filter(person -> person.getAge() > 18)
                   .count();

In the above example, we first use the filter() method to filter out the people who are not over 18 years old. Then we use the count() method to count the remaining people in the list. Finally, we chain these two methods together into a single lambda expression. The result is the number of people over 18 years old.