Java8で独自のStreamを作成する ref: http://qiita.com/tag1216/items/3ebe6bf69903026a0520

file0.java

Stream<String> stream = Stream.of("a", "b");
stream.forEach(System.out::println);

file1.java

Stream.Builder<Integer> builder = Stream.builder();
for (int i = 0; i < 5; i++) {
    builder.add(i);
}
Stream<Integer> stream = builder.build();
stream.forEach(System.out::println);

file2.java

Stream<Double> stream = Stream.generate(() -> Math.random());
stream.limit(3).forEach(System.out::println);

file3.java

Stream<Integer> stream = Stream.iterate(2, x -> x * 2);
stream.limit(8).forEach(System.out::println);
//結果
//2
//4
//8
//16
//32
//64
//128
//256

file4.java

Iterator<Integer> itr = new Iterator<Integer>() {
    public boolean hasNext() {
        return true;
    }
    public Integer next() {
        return (int) (Math.random() * 100);
    }
};
Spliterator<Integer> spliterator = 
        Spliterators.spliteratorUnknownSize(itr, Spliterator.NONNULL);
Stream<Integer> stream = StreamSupport.stream(spliterator, true);
stream.limit(5).forEach(System.out::println);

QiitaApiExamples.java

import static java.util.Spliterator.*;

import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import java.util.Iterator;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.function.Consumer;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;

import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

import com.google.gson.Gson;
import com.google.gson.stream.JsonReader;

public class QiitaApiExamples {

    public static void items(Consumer<Stream<Item>> consumer)
            throws ClientProtocolException, IOException {
        Gson gson = new Gson();
        HttpGet httpGet = new HttpGet("http://qiita.com/api/v2/items");
        try (
                CloseableHttpClient httpClient = HttpClients.createDefault();
                CloseableHttpResponse res = httpClient.execute(httpGet);
                JsonReader reader = new JsonReader(new InputStreamReader(
                        res.getEntity().getContent(), StandardCharsets.UTF_8))
        ) {
            reader.beginArray();
            Iterator<Item> itr = new Iterator<Item>() {
                public boolean hasNext() {
                    try {
                        return reader.hasNext();
                    } catch (IOException e) {
                        e.printStackTrace();
                        return false;
                    }
                }
                public Item next() {
                    return gson.fromJson(reader, Item.class);
                }
            };
            Spliterator<Item> spliterator = Spliterators.spliteratorUnknownSize(
                    itr, NONNULL | ORDERED | SIZED);
            Stream<Item> stream = StreamSupport.stream(spliterator, false);
            consumer.accept(stream);
            reader.endArray();
        }
    }

    public static void main(String[] args) throws Exception {
        items(stream -> stream.forEach(System.out::println));
    }
}