Initializer.java

import static java.util.stream.Collectors.toList;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Objects;
import java.util.function.Function;

public interface Initializer<R> {

	public Collection<R> provide();

	static <T, R> Initializer<R> from(Collection<T> coll, Function<T, R> mapper) {
		Objects.requireNonNull(coll, "collection");
		Objects.requireNonNull(mapper, "mapper");
		List<R> results = coll.stream().filter(Objects::nonNull).map(mapper).collect(toList());
		return () -> results;
	}

	static <T, R> Initializer<R> from(T[] coll, Function<T, R> mapper) {
		Objects.requireNonNull(coll, "collection");
		Objects.requireNonNull(mapper, "mapper");
		ArrayList<R> results = new ArrayList<>(coll.length);
		for (int i = 0, len = coll.length; i < len; results.add(mapper.apply(coll[i])), i++);
		return () -> results;
	}

	
        default R[] provideArray(@SuppressWarnings("unchecked") R ... ignore) {
		return provide().toArray(ignore);
	}

}

InitializerUsageOnClass.java

import static java.util.Arrays.asList;

import java.util.Arrays;
import java.util.Collection;
import java.util.List;

public class InitializerUsageOnClass {

	private Collection<String> families;

	private Collection<Integer> paragraphSpacing =  Initializer.from(new String[]{"I","II","III"}, String::length).provide();


	private Integer [] familyNamesLenght;
			
	public InitializerUsageOnClass(List<Person> persons) {
		families = Initializer.from(persons, Person::familyName).provide();
		familyNamesLenght = Initializer.from(families, String::length).provideArray();
	}

	public Collection<String> families() {
		return families;
	}

	public Integer [] familyNamesLength() {
		return familyNamesLenght;
	}
	
	public Collection<Integer> paragraphSpacing() {
		return paragraphSpacing;
	}
	
	public static void main(String[] args) {

		List<Person> persons = asList(
				new Person("John", "Black"), 
				new Person("Peter", "Red"),
				new Person("Jack", "White"));

		InitializerUsageOnClass tmp = new InitializerUsageOnClass(persons);
		System.out.println(tmp.families());
		System.out.println(tmp.paragraphSpacing());
		System.out.println(Arrays.toString(tmp.familyNamesLength()));
	}
}