Filtering lists using java 8 lambda expressions

I have a project class:

class Project {
    List<Name> names;
    int year;
    public List<Name> getNames(){
        return names;
    }
}

Then I have another main function. I have a list < project > and must filter the project list according to the year and get the name list as the result

Can you tell me how to use Java 8 lambda expressions?

thank you

Solution

Well, you don't specify the exact filter criteria, but suppose you want to filter elements by a given year:

List<Name> names = projects.stream()
    .filter(p -> p.getYear() == someYear) // keep only projects of a 
                                         // given year
    .flatMap(p -> p.getNames().stream()) // get a Stream of all the
                                        // Names of all Projects
                                        // that passed the filter
    .collect(Collectors.toList());     // collect to a List