+clu #17870 add Java api for joinSeedNodes

akka-cluster/src/main/scala/akka/cluster/Cluster.scala

@@ -12,6 +12,7 @@ import akka.ConfigurationException
 import akka.actor._
 import akka.dispatch.MonitorableThreadFactory
 import akka.event.{ Logging, LoggingAdapter }
+import akka.japi.Util
 import akka.pattern._
 import akka.remote.{ DefaultFailureDetectorRegistry, FailureDetector, _ }
 import com.typesafe.config.{ Config, ConfigFactory }
@@ -265,13 +266,23 @@ class Cluster(val system: ExtendedActorSystem) extends Extension {
    * An actor system can only join a cluster once. Additional attempts will be ignored.
    * When it has successfully joined it must be restarted to be able to join another
    * cluster or to join the same cluster again.
-   *
-   * JAVA API: Use akka.japi.Util.immutableSeq to convert a java.lang.Iterable
-   * to the type needed for the seedNodes parameter.
    */
   def joinSeedNodes(seedNodes: immutable.Seq[Address]): Unit =
     clusterCore ! InternalClusterAction.JoinSeedNodes(seedNodes.toVector)
 
+  /**
+   * Java API
+   *
+   * Join the specified seed nodes without defining them in config.
+   * Especially useful from tests when Addresses are unknown before startup time.
+   *
+   * An actor system can only join a cluster once. Additional attempts will be ignored.
+   * When it has successfully joined it must be restarted to be able to join another
+   * cluster or to join the same cluster again.
+   */
+  def joinSeedNodes(seedNodes: java.util.List[Address]): Unit =
+    joinSeedNodes(Util.immutableSeq(seedNodes))
+
   /**
    * Send command to issue state transition to LEAVING for the node specified by 'address'.
    * The member will go through the status changes [[MemberStatus]] `Leaving` (not published to

akka-cluster/src/multi-jvm/scala/akka/cluster/SingletonClusterSpec.scala

@@ -3,6 +3,7 @@
  */
 package akka.cluster
 
+import akka.actor.Address
 import com.typesafe.config.ConfigFactory
 import akka.remote.testkit.MultiNodeConfig
 import akka.remote.testkit.MultiNodeSpec
@@ -45,7 +46,8 @@ abstract class SingletonClusterSpec(multiNodeConfig: SingletonClusterMultiNodeCo
 
     "become singleton cluster when started with seed-nodes" taggedAs LongRunningTest in {
       runOn(first) {
-        cluster.joinSeedNodes(Vector(first))
+        val nodes: immutable.IndexedSeq[Address] = Vector(first) //
+        cluster.joinSeedNodes(nodes)
         awaitMembersUp(1)
         clusterView.isSingletonCluster should ===(true)
       }

akka-cluster/src/test/java/akka/cluster/ClusterJavaCompileTest.java

@@ -0,0 +1,26 @@
+/**
+ * Copyright (C) 2009-2015 Typesafe Inc. <http://www.typesafe.com>
+ */
+
+package akka.cluster;
+
+import akka.actor.ActorSystem;
+import akka.actor.Address;
+
+import java.util.Collections;
+import java.util.List;
+
+// Doc code, compile only
+@SuppressWarnings("ConstantConditions")
+public class ClusterJavaCompileTest {
+
+  final ActorSystem system = null;
+  final Cluster cluster = null;
+
+
+  public void compileJoinSeedNodesInJava() {
+    final List<Address> addresses = Collections.singletonList(new Address("akka.tcp", "MySystem"));
+    cluster.joinSeedNodes(addresses);
+  }
+
+}