[java8-guava] Java7-Guava-FluentIterable vs Java8-Guava-FluentIterable 예제

Java7의 Guava의 FluentIterable 과 Java8의 Guava의 FluentIterable 를 비교해서 코딩했다. 

import com.google.common.base.Function;
import com.google.common.base.Predicate;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.Lists;
import org.junit.Before;
import org.junit.Test;

import java.util.List;

import static org.junit.Assert.assertEquals;

public class GuavaTest {

    List<Person> persons = Lists.newArrayList();

    @Before
    public void before() {
        Person samuel = new Person(10, "Samuel");
        Person jason = new Person(25, "Jason");
        Person kelly = new Person(21, "Kelly");

        persons.add(samuel);
        persons.add(jason);
        persons.add(kelly);
    }

    @Test
    public void simpleGuavaWithJava7() {
        List<String> names = FluentIterable.from(persons)
                .filter(new Predicate<Person>() {
                    @Override
                    public boolean apply(Person person) {
                        return person.age() >= 20;
                    }
                })
                .transform(new Function<Person, String>() {
                    @Override
                    public String apply(Person person) {
                        return person.name();
                    }
                })
                .toList();

        assertEquals("Jason", names.get(0));
        assertEquals("Kelly", names.get(1));
        assertEquals(2, names.size());
    }

    @Test
    public void simpleGuavaWithJava8() {
        List<String> names = FluentIterable.from(persons)
                .filter(person -> person.age() >= 20)
                .transform(person -> person.name())
                .toList();

        assertEquals("Jason", names.get(0));
        assertEquals("Kelly", names.get(1));
        assertEquals(2, names.size());
    }
}

class Person {
    int age;
    String name;

    public Person(int age, String name) {
        this.age = age;
        this.name = name;
    }

    public int age() {
        return age;
    }

    public String name() {
        return name;
    }

}