pekko/akka-docs/src/test/java/jdocs/stream/SubstreamDocTest.java

/**
 *  Copyright (C) 2015-2017 Lightbend Inc. <http://www.lightbend.com/>
 */
package jdocs.stream;

import akka.actor.ActorSystem;
import akka.stream.ActorMaterializer;
import akka.stream.Materializer;
import akka.stream.javadsl.Sink;
import akka.stream.javadsl.Source;
import akka.testkit.javadsl.TestKit;
import jdocs.AbstractJavaTest;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class SubstreamDocTest  extends AbstractJavaTest {

    static ActorSystem system;
    static Materializer mat;

    @BeforeClass
    public static void setup() {
        system = ActorSystem.create("FlowDocTest");
        mat = ActorMaterializer.create(system);
    }

    @AfterClass
    public static void tearDown() {
        TestKit.shutdownActorSystem(system);
        system = null;
        mat = null;
    }

    @Test
    public void demonstrateGroupBy() throws Exception {
        //#groupBy1
        Source.from(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
          .groupBy(3, elem -> elem % 3);
        //#groupBy1

        //#groupBy2
        Source.from(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
          .groupBy(3, elem -> elem % 3)
          .to(Sink.ignore())
          .run(mat);
        //#groupBy2

        //#groupBy3
        Source.from(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
          .groupBy(3, elem -> elem % 3)
          .mergeSubstreams()
          .runWith(Sink.ignore(), mat);
        //#groupBy3

        //#groupBy4
        Source.from(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
          .groupBy(3, elem -> elem % 3)
          .mergeSubstreamsWithParallelism(2)
          .runWith(Sink.ignore(), mat);
        //concatSubstreams is equivalent to mergeSubstreamsWithParallelism(1)
        Source.from(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
          .groupBy(3, elem -> elem % 3)
          .concatSubstreams()
          .runWith(Sink.ignore(), mat);
        //#groupBy4
    }

    @Test
    public void demonstrateSplitWhenAfter() throws Exception {
        //#splitWhenAfter
        Source.from(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
          .splitWhen(elem -> elem == 3);

        Source.from(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
          .splitAfter(elem -> elem == 3);
        //#splitWhenAfter

        //#wordCount
        String text =
          "This is the first line.\n" +
          "The second line.\n" +
          "There is also the 3rd line\n";

        Source.from(Arrays.asList(text.split("")))
          .map(x -> x.charAt(0))
          .splitAfter(x -> x == '\n')
          .filter(x -> x != '\n')
          .map(x -> 1)
          .reduce((x,y) -> x + y)
          .to(Sink.foreach(x -> System.out.println(x)))
          .run(mat);
        //#wordCount
        Thread.sleep(1000);
    }

    @Test
    public void demonstrateflatMapConcatMerge() throws Exception {
        //#flatMapConcat
        Source.from(Arrays.asList(1, 2))
          .flatMapConcat(i -> Source.from(Arrays.asList(i, i, i)))
          .runWith(Sink.ignore(), mat);
        //#flatMapConcat

        //#flatMapMerge
        Source.from(Arrays.asList(1, 2))
          .flatMapMerge(2, i -> Source.from(Arrays.asList(i, i, i)))
          .runWith(Sink.ignore(), mat);
        //#flatMapMerge
    }
}