Sending using KafkaTemplate returns a exception for using String as a key

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1















When using Integer as a key this is not a problem, kafka should be able to handle Strings as a key.



ProducerFactory<String, String> pf =
new DefaultKafkaProducerFactory<String, String>(senderProps);
KafkaTemplate<String, String> template = new KafkaTemplate<>(pf);
ProducerRecord<String,String> pr = new ProducerRecord<>("my-topic", "key1","test");
template.send(pr);`


It throws below exception:




Org.apache.kafka.common.errors.SerializationException: Can't convert
key of class java.lang.String to class
org.apache.kafka.common.serialization.IntegerSerializer specified in
key.serializer



Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Integer
at org.apache.kafka.common.serialization.IntegerSerializer.serialize(IntegerSerializer.java:21)
at org.apache.kafka.common.serialization.ExtendedSerializer$Wrapper.serialize(ExtendedSerializer.java:65)
at org.apache.kafka.common.serialization.ExtendedSerializer$Wrapper.serialize(ExtendedSerializer.java:55)
at org.apache.kafka.clients.producer.KafkaProducer.doSend(KafkaProducer.java:799)
at org.apache.kafka.clients.producer.KafkaProducer.send(KafkaProducer.java:784)
at org.springframework.kafka.core.DefaultKafkaProducerFactory$CloseSafeProducer.send(DefaultKafkaProducerFactory.java:285)
at org.springframework.kafka.core.KafkaTemplate.doSend(KafkaTemplate.java:357)
at org.springframework.kafka.core.KafkaTemplate.send(KafkaTemplate.java:206)











share|improve this question





























    1















    When using Integer as a key this is not a problem, kafka should be able to handle Strings as a key.



    ProducerFactory<String, String> pf =
    new DefaultKafkaProducerFactory<String, String>(senderProps);
    KafkaTemplate<String, String> template = new KafkaTemplate<>(pf);
    ProducerRecord<String,String> pr = new ProducerRecord<>("my-topic", "key1","test");
    template.send(pr);`


    It throws below exception:




    Org.apache.kafka.common.errors.SerializationException: Can't convert
    key of class java.lang.String to class
    org.apache.kafka.common.serialization.IntegerSerializer specified in
    key.serializer



    Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Integer
    at org.apache.kafka.common.serialization.IntegerSerializer.serialize(IntegerSerializer.java:21)
    at org.apache.kafka.common.serialization.ExtendedSerializer$Wrapper.serialize(ExtendedSerializer.java:65)
    at org.apache.kafka.common.serialization.ExtendedSerializer$Wrapper.serialize(ExtendedSerializer.java:55)
    at org.apache.kafka.clients.producer.KafkaProducer.doSend(KafkaProducer.java:799)
    at org.apache.kafka.clients.producer.KafkaProducer.send(KafkaProducer.java:784)
    at org.springframework.kafka.core.DefaultKafkaProducerFactory$CloseSafeProducer.send(DefaultKafkaProducerFactory.java:285)
    at org.springframework.kafka.core.KafkaTemplate.doSend(KafkaTemplate.java:357)
    at org.springframework.kafka.core.KafkaTemplate.send(KafkaTemplate.java:206)











    share|improve this question



























      1












      1








      1








      When using Integer as a key this is not a problem, kafka should be able to handle Strings as a key.



      ProducerFactory<String, String> pf =
      new DefaultKafkaProducerFactory<String, String>(senderProps);
      KafkaTemplate<String, String> template = new KafkaTemplate<>(pf);
      ProducerRecord<String,String> pr = new ProducerRecord<>("my-topic", "key1","test");
      template.send(pr);`


      It throws below exception:




      Org.apache.kafka.common.errors.SerializationException: Can't convert
      key of class java.lang.String to class
      org.apache.kafka.common.serialization.IntegerSerializer specified in
      key.serializer



      Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Integer
      at org.apache.kafka.common.serialization.IntegerSerializer.serialize(IntegerSerializer.java:21)
      at org.apache.kafka.common.serialization.ExtendedSerializer$Wrapper.serialize(ExtendedSerializer.java:65)
      at org.apache.kafka.common.serialization.ExtendedSerializer$Wrapper.serialize(ExtendedSerializer.java:55)
      at org.apache.kafka.clients.producer.KafkaProducer.doSend(KafkaProducer.java:799)
      at org.apache.kafka.clients.producer.KafkaProducer.send(KafkaProducer.java:784)
      at org.springframework.kafka.core.DefaultKafkaProducerFactory$CloseSafeProducer.send(DefaultKafkaProducerFactory.java:285)
      at org.springframework.kafka.core.KafkaTemplate.doSend(KafkaTemplate.java:357)
      at org.springframework.kafka.core.KafkaTemplate.send(KafkaTemplate.java:206)











      share|improve this question
















      When using Integer as a key this is not a problem, kafka should be able to handle Strings as a key.



      ProducerFactory<String, String> pf =
      new DefaultKafkaProducerFactory<String, String>(senderProps);
      KafkaTemplate<String, String> template = new KafkaTemplate<>(pf);
      ProducerRecord<String,String> pr = new ProducerRecord<>("my-topic", "key1","test");
      template.send(pr);`


      It throws below exception:




      Org.apache.kafka.common.errors.SerializationException: Can't convert
      key of class java.lang.String to class
      org.apache.kafka.common.serialization.IntegerSerializer specified in
      key.serializer



      Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Integer
      at org.apache.kafka.common.serialization.IntegerSerializer.serialize(IntegerSerializer.java:21)
      at org.apache.kafka.common.serialization.ExtendedSerializer$Wrapper.serialize(ExtendedSerializer.java:65)
      at org.apache.kafka.common.serialization.ExtendedSerializer$Wrapper.serialize(ExtendedSerializer.java:55)
      at org.apache.kafka.clients.producer.KafkaProducer.doSend(KafkaProducer.java:799)
      at org.apache.kafka.clients.producer.KafkaProducer.send(KafkaProducer.java:784)
      at org.springframework.kafka.core.DefaultKafkaProducerFactory$CloseSafeProducer.send(DefaultKafkaProducerFactory.java:285)
      at org.springframework.kafka.core.KafkaTemplate.doSend(KafkaTemplate.java:357)
      at org.springframework.kafka.core.KafkaTemplate.send(KafkaTemplate.java:206)








      spring apache-kafka spring-kafka spring-kafka-test






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      edited Jan 3 at 9:20









      Nishu Tayal

      12.9k73584




      12.9k73584










      asked Jan 3 at 9:12









      kambokambo

      104




      104
























          2 Answers
          2






          active

          oldest

          votes


















          2














          Seems, your Key serializer is set as Integer in ProducerConfig. You need to set the KEY_SERIALIZER_CLASS_CONFIG as String :



          @Bean
          public Map<String, Object> producerConfigs() {
          Map<String, Object> props = new HashMap<>();
          props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
          props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
          props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
          return props;
          }





          share|improve this answer
























          • Thank you :) had to add StringDeserializer to the DefaultKafkaConsumerFactory aswell. Now it works well !

            – kambo
            Jan 3 at 9:43






          • 1





            Yeah, You need to add in Producer and consumer both whatever key and value type you are using :) If it helps you, please feel free to accept/upvote the answer :)

            – Nishu Tayal
            Jan 3 at 9:49






          • 1





            Please don't forget to accept the answer which solves your problem. It will help others :)

            – Nishu Tayal
            Jan 3 at 12:18











          • +1 for accepting this answer, please. That's the way how SO works: stackoverflow.com/help/someone-answers

            – Artem Bilan
            Jan 3 at 14:40











          • thank you, didn't know about that :)

            – kambo
            Jan 4 at 21:45



















          0














          It looks like you have configured as keySerializer: IntegerSerializer, but you sent messages with key of type String. You should change serializer type or type of key, to match to each other






          share|improve this answer























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            2 Answers
            2






            active

            oldest

            votes








            2 Answers
            2






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            2














            Seems, your Key serializer is set as Integer in ProducerConfig. You need to set the KEY_SERIALIZER_CLASS_CONFIG as String :



            @Bean
            public Map<String, Object> producerConfigs() {
            Map<String, Object> props = new HashMap<>();
            props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
            props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
            props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
            return props;
            }





            share|improve this answer
























            • Thank you :) had to add StringDeserializer to the DefaultKafkaConsumerFactory aswell. Now it works well !

              – kambo
              Jan 3 at 9:43






            • 1





              Yeah, You need to add in Producer and consumer both whatever key and value type you are using :) If it helps you, please feel free to accept/upvote the answer :)

              – Nishu Tayal
              Jan 3 at 9:49






            • 1





              Please don't forget to accept the answer which solves your problem. It will help others :)

              – Nishu Tayal
              Jan 3 at 12:18











            • +1 for accepting this answer, please. That's the way how SO works: stackoverflow.com/help/someone-answers

              – Artem Bilan
              Jan 3 at 14:40











            • thank you, didn't know about that :)

              – kambo
              Jan 4 at 21:45
















            2














            Seems, your Key serializer is set as Integer in ProducerConfig. You need to set the KEY_SERIALIZER_CLASS_CONFIG as String :



            @Bean
            public Map<String, Object> producerConfigs() {
            Map<String, Object> props = new HashMap<>();
            props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
            props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
            props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
            return props;
            }





            share|improve this answer
























            • Thank you :) had to add StringDeserializer to the DefaultKafkaConsumerFactory aswell. Now it works well !

              – kambo
              Jan 3 at 9:43






            • 1





              Yeah, You need to add in Producer and consumer both whatever key and value type you are using :) If it helps you, please feel free to accept/upvote the answer :)

              – Nishu Tayal
              Jan 3 at 9:49






            • 1





              Please don't forget to accept the answer which solves your problem. It will help others :)

              – Nishu Tayal
              Jan 3 at 12:18











            • +1 for accepting this answer, please. That's the way how SO works: stackoverflow.com/help/someone-answers

              – Artem Bilan
              Jan 3 at 14:40











            • thank you, didn't know about that :)

              – kambo
              Jan 4 at 21:45














            2












            2








            2







            Seems, your Key serializer is set as Integer in ProducerConfig. You need to set the KEY_SERIALIZER_CLASS_CONFIG as String :



            @Bean
            public Map<String, Object> producerConfigs() {
            Map<String, Object> props = new HashMap<>();
            props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
            props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
            props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
            return props;
            }





            share|improve this answer













            Seems, your Key serializer is set as Integer in ProducerConfig. You need to set the KEY_SERIALIZER_CLASS_CONFIG as String :



            @Bean
            public Map<String, Object> producerConfigs() {
            Map<String, Object> props = new HashMap<>();
            props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
            props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
            props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
            return props;
            }






            share|improve this answer












            share|improve this answer



            share|improve this answer










            answered Jan 3 at 9:23









            Nishu TayalNishu Tayal

            12.9k73584




            12.9k73584













            • Thank you :) had to add StringDeserializer to the DefaultKafkaConsumerFactory aswell. Now it works well !

              – kambo
              Jan 3 at 9:43






            • 1





              Yeah, You need to add in Producer and consumer both whatever key and value type you are using :) If it helps you, please feel free to accept/upvote the answer :)

              – Nishu Tayal
              Jan 3 at 9:49






            • 1





              Please don't forget to accept the answer which solves your problem. It will help others :)

              – Nishu Tayal
              Jan 3 at 12:18











            • +1 for accepting this answer, please. That's the way how SO works: stackoverflow.com/help/someone-answers

              – Artem Bilan
              Jan 3 at 14:40











            • thank you, didn't know about that :)

              – kambo
              Jan 4 at 21:45



















            • Thank you :) had to add StringDeserializer to the DefaultKafkaConsumerFactory aswell. Now it works well !

              – kambo
              Jan 3 at 9:43






            • 1





              Yeah, You need to add in Producer and consumer both whatever key and value type you are using :) If it helps you, please feel free to accept/upvote the answer :)

              – Nishu Tayal
              Jan 3 at 9:49






            • 1





              Please don't forget to accept the answer which solves your problem. It will help others :)

              – Nishu Tayal
              Jan 3 at 12:18











            • +1 for accepting this answer, please. That's the way how SO works: stackoverflow.com/help/someone-answers

              – Artem Bilan
              Jan 3 at 14:40











            • thank you, didn't know about that :)

              – kambo
              Jan 4 at 21:45

















            Thank you :) had to add StringDeserializer to the DefaultKafkaConsumerFactory aswell. Now it works well !

            – kambo
            Jan 3 at 9:43





            Thank you :) had to add StringDeserializer to the DefaultKafkaConsumerFactory aswell. Now it works well !

            – kambo
            Jan 3 at 9:43




            1




            1





            Yeah, You need to add in Producer and consumer both whatever key and value type you are using :) If it helps you, please feel free to accept/upvote the answer :)

            – Nishu Tayal
            Jan 3 at 9:49





            Yeah, You need to add in Producer and consumer both whatever key and value type you are using :) If it helps you, please feel free to accept/upvote the answer :)

            – Nishu Tayal
            Jan 3 at 9:49




            1




            1





            Please don't forget to accept the answer which solves your problem. It will help others :)

            – Nishu Tayal
            Jan 3 at 12:18





            Please don't forget to accept the answer which solves your problem. It will help others :)

            – Nishu Tayal
            Jan 3 at 12:18













            +1 for accepting this answer, please. That's the way how SO works: stackoverflow.com/help/someone-answers

            – Artem Bilan
            Jan 3 at 14:40





            +1 for accepting this answer, please. That's the way how SO works: stackoverflow.com/help/someone-answers

            – Artem Bilan
            Jan 3 at 14:40













            thank you, didn't know about that :)

            – kambo
            Jan 4 at 21:45





            thank you, didn't know about that :)

            – kambo
            Jan 4 at 21:45













            0














            It looks like you have configured as keySerializer: IntegerSerializer, but you sent messages with key of type String. You should change serializer type or type of key, to match to each other






            share|improve this answer




























              0














              It looks like you have configured as keySerializer: IntegerSerializer, but you sent messages with key of type String. You should change serializer type or type of key, to match to each other






              share|improve this answer


























                0












                0








                0







                It looks like you have configured as keySerializer: IntegerSerializer, but you sent messages with key of type String. You should change serializer type or type of key, to match to each other






                share|improve this answer













                It looks like you have configured as keySerializer: IntegerSerializer, but you sent messages with key of type String. You should change serializer type or type of key, to match to each other







                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Jan 3 at 9:22









                wardziniakwardziniak

                1,6021616




                1,6021616






























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