Make use of eq and ne.

actor-testkit-typed/src/main/scala/org/apache/pekko/actor/testkit/typed/internal/LoggingTestKitImpl.scala

@@ -71,7 +71,7 @@ import pekko.testkit.TestKit
   }
 
   private def messageOrEmpty(event: LoggingEvent): String =
-    if (event.message == null) "" else event.message
+    if (event.message eq null) "" else event.message
 
   private def sourceOrEmpty(event: LoggingEvent): String =
     event.mdc.getOrElse("pekkoSource", "")

actor-typed/src/main/scala/org/apache/pekko/actor/typed/SpawnProtocol.scala

@@ -67,7 +67,7 @@ object SpawnProtocol {
       msg match {
         case Spawn(bhvr: Behavior[t], name, props, replyTo) =>
           val ref =
-            if (name == null || name.equals(""))
+            if ((name eq null) || name.equals(""))
               ctx.spawnAnonymous(bhvr, props)
             else {
 

actor-typed/src/main/scala/org/apache/pekko/actor/typed/internal/ActorContextImpl.scala

@@ -285,7 +285,7 @@ import scala.util.Success
       future: CompletionStage[Value],
       applyToResult: pekko.japi.function.Function2[Value, Throwable, T]): Unit = {
     future.handle[Unit] { (value, ex) =>
-      if (ex != null)
+      if (ex ne null)
         self.unsafeUpcast ! AdaptMessage(ex, applyToResult.apply(null.asInstanceOf[Value], _: Throwable))
       else self.unsafeUpcast ! AdaptMessage(value, applyToResult.apply(_: Value, null))
     }

actor-typed/src/main/scala/org/apache/pekko/actor/typed/internal/PropsImpl.scala

@@ -66,7 +66,7 @@ import pekko.annotation.InternalApi
   }
 
   final case class ActorTagsImpl(tags: Set[String], next: Props = Props.empty) extends ActorTags {
-    if (tags == null)
+    if (tags eq null)
       throw new IllegalArgumentException("Tags must not be null")
     def withNext(next: Props): Props = copy(next = next)
   }

actor-typed/src/main/scala/org/apache/pekko/actor/typed/internal/StashBufferImpl.scala

@@ -144,7 +144,7 @@ import java.util.function.Predicate
   override def exists(predicate: T => Boolean): Boolean = {
     var hasElement = false
     var node = _first
-    while (node != null && !hasElement) {
+    while ((node ne null) && !hasElement) {
       hasElement = predicate(node.message)
       node = node.next
     }

actor-typed/src/main/scala/org/apache/pekko/actor/typed/javadsl/Behaviors.scala

@@ -403,12 +403,12 @@ object Behaviors {
       behavior: Behavior[T]): Behavior[T] = {
 
     def asScalaMap(m: java.util.Map[String, String]): Map[String, String] = {
-      if (m == null || m.isEmpty) Map.empty[String, String]
+      if ((m eq null) || m.isEmpty) Map.empty[String, String]
       else m.asScala.toMap
     }
 
     val mdcForMessageFun: T => Map[String, String] =
-      if (mdcForMessage == null) _ => Map.empty
+      if (mdcForMessage eq null) _ => Map.empty
       else { message =>
         asScalaMap(mdcForMessage.apply(message))
       }

actor/src/main/scala/org/apache/pekko/actor/Actor.scala

@@ -89,7 +89,7 @@ final case class Identify(messageId: Any) extends AutoReceivedMessage with NotIn
  */
 @SerialVersionUID(1L)
 final case class ActorIdentity(correlationId: Any, ref: Option[ActorRef]) {
-  if (ref.isDefined && ref.get == null) {
+  if (ref.isDefined && (ref.get eq null)) {
     throw new IllegalArgumentException(
       "ActorIdentity created with ref = Some(null) is not allowed, " +
       "this could happen when serializing with Scala 2.12 and deserializing with Scala 2.11 which is not supported.")
@@ -201,7 +201,7 @@ class ActorInitializationException protected (actor: ActorRef, message: String,
 }
 object ActorInitializationException {
   private def enrichedMessage(actor: ActorRef, message: String) =
-    if (actor == null) message else s"${actor.path}: $message"
+    if (actor eq null) message else s"${actor.path}: $message"
   private[pekko] def apply(actor: ActorRef, message: String, cause: Throwable = null): ActorInitializationException =
     new ActorInitializationException(actor, message, cause)
   private[pekko] def apply(message: String): ActorInitializationException =
@@ -230,7 +230,7 @@ final case class PreRestartException private[pekko] (
     extends ActorInitializationException(
       actor,
       "exception in preRestart(" +
-      (if (originalCause == null) "null" else originalCause.getClass) + ", " +
+      (if (originalCause eq null) "null" else originalCause.getClass) + ", " +
       (messageOption match { case Some(m: AnyRef) => m.getClass; case _ => "None" }) +
       ")",
       cause)
@@ -247,7 +247,7 @@ final case class PreRestartException private[pekko] (
 final case class PostRestartException private[pekko] (actor: ActorRef, cause: Throwable, originalCause: Throwable)
     extends ActorInitializationException(
       actor,
-      "exception post restart (" + (if (originalCause == null) "null" else originalCause.getClass) + ")",
+      "exception post restart (" + (if (originalCause eq null) "null" else originalCause.getClass) + ")",
       cause)
 
 /**

actor/src/main/scala/org/apache/pekko/actor/ActorCell.scala

@@ -641,7 +641,7 @@ private[pekko] class ActorCell(
 
   protected def create(failure: Option[ActorInitializationException]): Unit = {
     def failActor(): Unit =
-      if (_actor != null) {
+      if (_actor ne null) {
         clearActorFields(actor, recreate = false)
         _actor = null // ensure that we know that we failed during creation
       }
@@ -684,7 +684,7 @@ private[pekko] class ActorCell(
 
   @tailrec
   private def rootCauseOf(throwable: Throwable): Throwable = {
-    if (throwable.getCause != null && throwable.getCause != throwable)
+    if ((throwable.getCause ne null) && throwable.getCause != throwable)
       rootCauseOf(throwable.getCause)
     else
       throwable

actor/src/main/scala/org/apache/pekko/actor/Address.scala

@@ -188,15 +188,15 @@ object AddressFromURIString {
 
   def unapply(uri: URI): Option[Address] =
     if (uri eq null) None
-    else if (uri.getScheme == null || (uri.getUserInfo == null && uri.getHost == null)) None
-    else if (uri.getUserInfo == null) { // case 1: “pekko://system”
+    else if ((uri.getScheme eq null) || (uri.getUserInfo == null && (uri.getHost eq null))) None
+    else if (uri.getUserInfo eq null) { // case 1: “pekko://system”
       if (uri.getPort != -1) None
       else Some(Address(uri.getScheme, uri.getHost))
     } else { // case 2: “pekko://system@host:port”
-      if (uri.getHost == null || uri.getPort == -1) None
+      if ((uri.getHost eq null) || uri.getPort == -1) None
       else
         Some(
-          if (uri.getUserInfo == null) Address(uri.getScheme, uri.getHost)
+          if (uri.getUserInfo eq null) Address(uri.getScheme, uri.getHost)
           else Address(uri.getScheme, uri.getUserInfo, uri.getHost, uri.getPort))
     }
 

actor/src/main/scala/org/apache/pekko/actor/FSM.scala

@@ -696,22 +696,22 @@ trait FSM[S, D] extends Actor with Listeners with ActorLogging {
    * @see [[#startWith]]
    */
   final def initialize(): Unit =
-    if (currentState != null) makeTransition(currentState)
+    if (currentState ne null) makeTransition(currentState)
     else throw new IllegalStateException("You must call `startWith` before calling `initialize`")
 
   /**
    * Return current state name (i.e. object of type S)
    */
   final def stateName: S = {
-    if (currentState != null) currentState.stateName
+    if (currentState ne null) currentState.stateName
     else throw new IllegalStateException("You must call `startWith` before using `stateName`")
   }
 
   /**
    * Return current state data (i.e. object of type D)
    */
   final def stateData: D =
-    if (currentState != null) currentState.stateData
+    if (currentState ne null) currentState.stateData
     else throw new IllegalStateException("You must call `startWith` before using `stateData`")
 
   /**

actor/src/main/scala/org/apache/pekko/actor/LightArrayRevolverScheduler.scala

@@ -144,7 +144,7 @@ class LightArrayRevolverScheduler(config: Config, log: LoggingAdapter, threadFac
               try {
                 runnable.run()
                 val driftNanos = clock() - getAndAdd(delay.toNanos)
-                if (self.get() != null)
+                if (self.get() ne null)
                   swap(schedule(executor, this, Duration.fromNanos(Math.max(delay.toNanos - driftNanos, 1))))
               } catch {
                 case _: SchedulerException => // ignore failure to enqueue or terminated target actor
@@ -204,10 +204,10 @@ class LightArrayRevolverScheduler(config: Config, log: LoggingAdapter, threadFac
 
   private def schedule(ec: ExecutionContext, r: Runnable, delay: FiniteDuration): TimerTask =
     if (delay.length <= 0L) { // use simple comparison instead of Ordering for performance
-      if (stopped.get != null) throw SchedulerException("cannot enqueue after timer shutdown")
+      if (stopped.get ne null) throw SchedulerException("cannot enqueue after timer shutdown")
       ec.execute(r)
       NotCancellable
-    } else if (stopped.get != null) {
+    } else if (stopped.get ne null) {
       throw SchedulerException("cannot enqueue after timer shutdown")
     } else {
       val delayNanos = delay.toNanos
@@ -216,7 +216,7 @@ class LightArrayRevolverScheduler(config: Config, log: LoggingAdapter, threadFac
       val ticks = (delayNanos / tickNanos).toInt
       val task = new TaskHolder(r, ticks, ec)
       queue.add(task)
-      if (stopped.get != null && task.cancel())
+      if ((stopped.get ne null) && task.cancel())
         throw SchedulerException("cannot enqueue after timer shutdown")
       task
     }

actor/src/main/scala/org/apache/pekko/actor/Scheduler.scala

@@ -89,12 +89,12 @@ trait Scheduler {
           override def run(): Unit = {
             try {
               runnable.run()
-              if (get != null)
+              if (get ne null)
                 swap(scheduleOnce(delay, this))
             } catch {
               // ignore failure to enqueue or terminated target actor
-              case _: SchedulerException                                                                         =>
-              case e: IllegalStateException if e.getCause != null && e.getCause.isInstanceOf[SchedulerException] =>
+              case _: SchedulerException                                                                           =>
+              case e: IllegalStateException if (e.getCause ne null) && e.getCause.isInstanceOf[SchedulerException] =>
             }
           }
 
@@ -541,7 +541,7 @@ object Scheduler {
 
     @tailrec final protected def swap(c: Cancellable): Unit = {
       get match {
-        case null => if (c != null) c.cancel()
+        case null => if (c ne null) c.cancel()
         case old  =>
           if (!compareAndSet(old, c))
             swap(c)

actor/src/main/scala/org/apache/pekko/actor/dungeon/Dispatch.scala

@@ -96,7 +96,7 @@ private[pekko] trait Dispatch { this: ActorCell =>
         val req = system.mailboxes.getRequiredType(actorClass)
         if (req.isInstance(mbox.messageQueue)) Create(None)
         else {
-          val gotType = if (mbox.messageQueue == null) "null" else mbox.messageQueue.getClass.getName
+          val gotType = if (mbox.messageQueue eq null) "null" else mbox.messageQueue.getClass.getName
           Create(Some(ActorInitializationException(self, s"Actor [$self] requires mailbox type [$req] got [$gotType]")))
         }
       case _ => Create(None)

actor/src/main/scala/org/apache/pekko/actor/dungeon/FaultHandling.scala

@@ -90,7 +90,7 @@ private[pekko] trait FaultHandling { this: ActorCell =>
    * Do re-create the actor in response to a failure.
    */
   protected def faultRecreate(cause: Throwable): Unit =
-    if (actor == null) {
+    if (actor eq null) {
       system.eventStream.publish(
         Error(self.path.toString, clazz(actor), "changing Recreate into Create after " + cause))
       faultCreate()
@@ -134,11 +134,11 @@ private[pekko] trait FaultHandling { this: ActorCell =>
    *        prompted this action.
    */
   protected def faultResume(causedByFailure: Throwable): Unit = {
-    if (actor == null) {
+    if (actor eq null) {
       system.eventStream.publish(
         Error(self.path.toString, clazz(actor), "changing Resume into Create after " + causedByFailure))
       faultCreate()
-    } else if (isFailedFatally && causedByFailure != null) {
+    } else if (isFailedFatally && (causedByFailure ne null)) {
       system.eventStream.publish(
         Error(self.path.toString, clazz(actor), "changing Resume into Restart after " + causedByFailure))
       faultRecreate(causedByFailure)
@@ -147,7 +147,7 @@ private[pekko] trait FaultHandling { this: ActorCell =>
       // done always to keep that suspend counter balanced
       // must happen “atomically”
       try resumeNonRecursive()
-      finally if (causedByFailure != null) clearFailed()
+      finally if (causedByFailure ne null) clearFailed()
       resumeChildren(causedByFailure, perp)
     }
   }
@@ -331,7 +331,7 @@ private[pekko] trait FaultHandling { this: ActorCell =>
      * otherwise tell the supervisor etc. (in that second case, the match
      * below will hit the empty default case, too)
      */
-    if (actor != null) {
+    if (actor ne null) {
       try actor.supervisorStrategy.handleChildTerminated(this, child, children)
       catch handleNonFatalOrInterruptedException { e =>
           publish(Error(e, self.path.toString, clazz(actor), "handleChildTerminated failed"))

actor/src/main/scala/org/apache/pekko/dispatch/VirtualThreadSupport.scala

@@ -85,7 +85,7 @@ private[dispatch] object VirtualThreadSupport {
       val ofVirtualClass = ClassLoader.getSystemClassLoader.loadClass("java.lang.Thread$Builder$OfVirtual")
       val ofVirtualMethod = classOf[Thread].getDeclaredMethod("ofVirtual")
       var builder = ofVirtualMethod.invoke(null)
-      if (executor != null) {
+      if (executor ne null) {
         val clazz = builder.getClass
         val field = clazz.getDeclaredField("scheduler")
         field.setAccessible(true)

actor/src/main/scala/org/apache/pekko/event/EventStream.scala

@@ -49,7 +49,7 @@ class EventStream(sys: ActorSystem, private val debug: Boolean) extends LoggingB
   protected def classify(event: Any): Class[_] = event.getClass
 
   protected def publish(event: Any, subscriber: ActorRef) = {
-    if (sys == null && subscriber.isTerminated) unsubscribe(subscriber)
+    if ((sys eq null) && subscriber.isTerminated) unsubscribe(subscriber)
     else subscriber ! event
   }
 

actor/src/main/scala/org/apache/pekko/event/Logging.scala

@@ -1647,7 +1647,7 @@ trait DiagnosticLoggingAdapter extends LoggingAdapter {
    * These values can be used in PatternLayout when `org.apache.pekko.event.slf4j.Slf4jLogger` is configured.
    * Visit <a href="https://logback.qos.ch/manual/mdc.html">Logback Docs: MDC</a> for more information.
    */
-  def mdc(mdc: MDC): Unit = _mdc = if (mdc != null) mdc else emptyMDC
+  def mdc(mdc: MDC): Unit = _mdc = if (mdc ne null) mdc else emptyMDC
 
   /**
    * Java API:
@@ -1675,7 +1675,7 @@ trait DiagnosticLoggingAdapter extends LoggingAdapter {
    * These values can be used in PatternLayout when `org.apache.pekko.event.slf4j.Slf4jLogger` is configured.
    * Visit <a href="https://logback.qos.ch/manual/mdc.html">Logback Docs: MDC</a> for more information.
    */
-  def setMDC(jMdc: java.util.Map[String, Any]): Unit = mdc(if (jMdc != null) jMdc.asScala.toMap else emptyMDC)
+  def setMDC(jMdc: java.util.Map[String, Any]): Unit = mdc(if (jMdc ne null) jMdc.asScala.toMap else emptyMDC)
 
   /**
    * Clear all entries in the MDC

actor/src/main/scala/org/apache/pekko/io/DirectByteBufferPool.scala

@@ -57,7 +57,7 @@ private[pekko] class DirectByteBufferPool(defaultBufferSize: Int, maxPoolEntries
     }
 
     // allocate new and clear outside the lock
-    if (buffer == null)
+    if (buffer eq null)
       allocate(defaultBufferSize)
     else {
       buffer.clear()

actor/src/main/scala/org/apache/pekko/io/Tcp.scala

@@ -484,9 +484,9 @@ object Tcp extends ExtensionId[TcpExt] with ExtensionIdProvider {
       _cause
         .map(t => {
           val msg =
-            if (t.getCause == null)
+            if (t.getCause eq null)
               t.getMessage
-            else if (t.getCause.getCause == null)
+            else if (t.getCause.getCause eq null)
               s"${t.getMessage}, caused by: ${t.getCause}"
             else
               s"${t.getMessage}, caused by: ${t.getCause}, caused by: ${t.getCause.getCause}"

actor/src/main/scala/org/apache/pekko/io/TcpConnection.scala

@@ -366,7 +366,7 @@ private[io] abstract class TcpConnection(val tcp: TcpExt, val channel: SocketCha
     }
 
   @tailrec private[this] def extractMsg(t: Throwable): String =
-    if (t == null) "unknown"
+    if (t eq null) "unknown"
     else {
       t.getMessage match {
         case null | "" => extractMsg(t.getCause)

actor/src/main/scala/org/apache/pekko/io/TcpListener.scala

@@ -140,7 +140,7 @@ private[io] class TcpListener(
           case NonFatal(e) => { log.error(e, "Accept error: could not accept new connection"); null }
         }
       } else null
-    if (socketChannel != null) {
+    if (socketChannel ne null) {
       log.debug("New connection accepted")
       socketChannel.configureBlocking(false)
       def props(registry: ChannelRegistry) =

actor/src/main/scala/org/apache/pekko/io/UdpConnection.scala

@@ -170,7 +170,7 @@ private[io] class UdpConnection(
   }
 
   override def postStop(): Unit =
-    if (channel != null && channel.isOpen) {
+    if ((channel ne null) && channel.isOpen) {
       log.debug("Closing DatagramChannel after being stopped")
       try channel.close()
       catch {

actor/src/main/scala/org/apache/pekko/io/dns/DnsSettings.scala

@@ -222,7 +222,7 @@ object DnsSettings {
         val ctx = new InitialDirContext(env)
         val dnsUrls = ctx.getEnvironment.get("java.naming.provider.url").asInstanceOf[String]
         // Only try if not empty as otherwise we will produce an exception
-        if (dnsUrls != null && !dnsUrls.isEmpty) {
+        if ((dnsUrls ne null) && !dnsUrls.isEmpty) {
           val servers = dnsUrls.split(" ")
           servers.flatMap { server =>
             asInetSocketAddress(server).toOption

actor/src/main/scala/org/apache/pekko/pattern/AskSupport.scala

@@ -422,7 +422,7 @@ final class ExplicitlyAskableActorRef(val actorRef: ActorRef) extends AnyVal {
             s"question not sent to [$actorRef]."))
       case _ =>
         val message =
-          if (sender == null) null else messageFactory(sender.asInstanceOf[InternalActorRef].provider.deadLetters)
+          if (sender eq null) null else messageFactory(sender.asInstanceOf[InternalActorRef].provider.deadLetters)
         Future.failed[Any](AskableActorRef.unsupportedRecipientType(actorRef, message, sender))
     }
 }
@@ -501,7 +501,7 @@ final class ExplicitlyAskableActorSelection(val actorSel: ActorSelection) extend
             s"question not sent to [$actorSel]."))
       case _ =>
         val message =
-          if (sender == null) null else messageFactory(sender.asInstanceOf[InternalActorRef].provider.deadLetters)
+          if (sender eq null) null else messageFactory(sender.asInstanceOf[InternalActorRef].provider.deadLetters)
         Future.failed[Any](AskableActorRef.unsupportedRecipientType(actorSel, message, sender))
     }
 }

actor/src/main/scala/org/apache/pekko/pattern/CircuitBreaker.scala

@@ -764,7 +764,7 @@ class CircuitBreaker(
 
   private def isIgnoredException(ex: Any): Boolean =
     allowExceptions.nonEmpty && (ex match {
-      case ce: CompletionException => ce.getCause != null && allowExceptions.contains(ce.getCause.getClass.getName)
+      case ce: CompletionException => (ce.getCause ne null) && allowExceptions.contains(ce.getCause.getClass.getName)
       case _                       => allowExceptions.contains(ex.getClass.getName)
     })