From: Kai Moritz <kai@juplo.de>
Date: Wed, 10 Jun 2026 12:32:13 +0000 (+0200)
Subject: `ConsumerRebalanceListener` implementiert, der die Änderungen logged
X-Git-Tag: grundlagen/simple-consumer--2026-06-lvm--rebase-vollständig
X-Git-Url: http://juplo.de/gitweb/?a=commitdiff_plain;h=9d0c92f01c4d393b70655615abae808619530aac;p=demos%2Fkafka%2Ftraining

`ConsumerRebalanceListener` implementiert, der die Änderungen logged
---

diff --git a/src/main/java/de/juplo/kafka/ExampleConsumer.java b/src/main/java/de/juplo/kafka/ExampleConsumer.java
index 6f4e4e88..36ddc70d 100644
--- a/src/main/java/de/juplo/kafka/ExampleConsumer.java
+++ b/src/main/java/de/juplo/kafka/ExampleConsumer.java
@@ -1,20 +1,23 @@
 package de.juplo.kafka;
 
 import lombok.extern.slf4j.Slf4j;
+import org.apache.kafka.clients.consumer.ConsumerRebalanceListener;
 import org.apache.kafka.clients.consumer.ConsumerRecord;
 import org.apache.kafka.clients.consumer.ConsumerRecords;
 import org.apache.kafka.clients.consumer.Consumer;
 import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.common.TopicPartition;
 import org.apache.kafka.common.errors.WakeupException;
 import org.apache.kafka.common.serialization.StringDeserializer;
 
 import java.time.Duration;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.Properties;
 
 
 @Slf4j
-public class ExampleConsumer
+public class ExampleConsumer implements ConsumerRebalanceListener
 {
   private final String id;
   private final String topic;
@@ -47,7 +50,7 @@ public class ExampleConsumer
     try
     {
       log.info("{} - Subscribing to topic {}", id, topic);
-      consumer.subscribe(Arrays.asList(topic));
+      consumer.subscribe(Arrays.asList(topic), this);
       running = true;
 
       while (true)
@@ -95,6 +98,30 @@ public class ExampleConsumer
     log.info("{} - partition={}-{}, offset={}: {}={}", id, topic, partition, offset, key, value);
   }
 
+  @Override
+  public void onPartitionsAssigned(Collection<TopicPartition> partitions)
+  {
+    partitions
+      .stream()
+      .forEach(partition -> log.info("{} - partition assigned: {}", id, partition));
+  }
+
+  @Override
+  public void onPartitionsRevoked(Collection<TopicPartition> partitions)
+  {
+    partitions
+      .stream()
+      .forEach(partition -> log.info("{} - partition revoked: {}", id, partition));
+  }
+
+  @Override
+  public void onPartitionsLost(Collection<TopicPartition> partitions)
+  {
+    partitions
+      .stream()
+      .forEach(partition -> log.info("{} - partition lost: {}", id, partition));
+  }
+
 
   public static void main(String[] args) throws Exception
   {