Java 8, Lambdas and Anonymous Classes, ReactiveX fun

TST.java

package test;

import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.common.collect.Multimap;
import org.junit.Test;
import rx.Observable;
import rx.schedulers.Schedulers;

import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import static rx.Observable.from;
import static rx.Observable.just;

public class TST {

    @Test
    public void testName() throws Exception {

        final Map<Integer, String> objects = getObjects();
        final Multimap<String, Integer> bucket = getMap();

        just("D1", "D2", "D3")
                .flatMap((key) -> just(getBucket(bucket, key)))
                .flatMap((ids) -> getIds(ids, objects))
                .doOnNext(System.out::println)
                .subscribe();

    }

    private List getBucket(Multimap<String, Integer> bucket, String key) {
        return Arrays.asList(bucket.get(key));
    }

    private Observable<List<String>> getIds(List<Integer> ids, Map<Integer, String> objects) {

        List<String> res = Lists.newArrayList();

        from(ids)
                .subscribeOn(Schedulers.immediate())
                .map((i) -> {
                    String obj = objects.get(i);
                    if (obj == null) {
                        throw new RuntimeException("Unknown");
                    }
                    return obj;
                })
                .subscribe(
                        (element) -> {
                            res.add(element);
                        },
                        (error) -> {
                            res.add("N/A");
                        }
                );

        return just(res);
    }

    private Map<Integer, String> getObjects() {
        HashMap<Integer, String> map = Maps.newHashMap();
        map.put(1, "Lorem");
        map.put(2, "Ipsum");
        map.put(3, "Dolor");
        map.put(5, "Amet");
        return map;
    }

    private Multimap<String, Integer> getMap() {
        Multimap<String, Integer> bucket = ArrayListMultimap.create();
        bucket.putAll("D1", Lists.newArrayList(1, 3, 2));
        bucket.putAll("D2", Lists.newArrayList(2, 4));
        bucket.putAll("D3", Lists.newArrayList(1, 4, 5));
        return bucket;
    }


}