Java 8: Lambda expressions

Based on The Java™ Tutorials: Lambda Expressions

One simplistic approach is to create several methods; each method searches for members that match one characteristic, such as gender or age. The following method prints members that are older than a specified age:

public void printPersonsOlderThan(List<Person> roster, int age) {
    for (Person p : roster) {
        if (p.getAge() >= age) {
            p.printPerson();
        }
    }
}

Note: A List is an ordered Collection. A collection is an object that groups multiple elements into a single unit. Collections are used to store, retrieve, manipulate, and communicate aggregate data. For more information about collections, see the Collections trail.

This approach can potentially make your application brittle, which is the likelihood of an application not working because of the introduction of updates (such as newer data types). Suppose that you upgrade your application and change the structure of the Person class such that it contains different member variables; perhaps the class records and measures ages with a different data type or algorithm. You would have to rewrite a lot of your API to accommodate this change. In addition, this approach is unnecessarily restrictive; what if you wanted to print members younger than a certain age, for example?