Akka/Scala example source code file (JavaExtension.java)

This example Akka source code file (JavaExtension.java) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Akka and Scala source code examples by using tags.

All credit for the original source code belongs to akka.io; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Akka tags/keywords

actor, akka, akkajunitactorsystemresource, classrule, extendedactorsystem, extension, extensionid, javaextension, otherextension, test, testextension, testextensionid, testing, testkit

The JavaExtension.java Akka example source code

/**
 * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
 */
package akka.actor;

import akka.testkit.AkkaJUnitActorSystemResource;
import org.junit.*;
import akka.testkit.AkkaSpec;
import com.typesafe.config.ConfigFactory;

import static org.junit.Assert.*;

public class JavaExtension {

  static class TestExtensionId extends AbstractExtensionId<TestExtension> implements ExtensionIdProvider {
    public final static TestExtensionId TestExtensionProvider = new TestExtensionId();

    public ExtensionId<TestExtension> lookup() {
      return TestExtensionId.TestExtensionProvider;
    }

    public TestExtension createExtension(ExtendedActorSystem i) {
      return new TestExtension(i);
    }
  }

  static class TestExtension implements Extension {
    public final ExtendedActorSystem system;

    public TestExtension(ExtendedActorSystem i) {
      system = i;
    }
  }

  static class OtherExtension implements Extension {
    static final ExtensionKey<OtherExtension> key = new ExtensionKey<OtherExtension>(OtherExtension.class) {
    };

    public final ExtendedActorSystem system;

    public OtherExtension(ExtendedActorSystem system) {
      this.system = system;
    }
  }

  @ClassRule
  public static AkkaJUnitActorSystemResource actorSystemResource =
    new AkkaJUnitActorSystemResource("JavaExtension",
      ConfigFactory.parseString("akka.extensions = [ \"akka.actor.JavaExtension$TestExtensionId\" ]")
      .withFallback(AkkaSpec.testConf()));

  private final ActorSystem system = actorSystemResource.getSystem();

  @Test
  public void mustBeAccessible() {
    assertTrue(system.hasExtension((TestExtensionId.TestExtensionProvider)));
    assertSame(system.extension(TestExtensionId.TestExtensionProvider).system, system);
    assertSame(TestExtensionId.TestExtensionProvider.apply(system).system, system);
  }

  @Test
  public void mustBeAdHoc() {
    assertSame(OtherExtension.key.apply(system).system, system);
  }

}