Receiving the Json data which i simply want to map on CarClass and want to create new stream but map method doesn't allow me it to map on custom datatype The method map(KeyValueMapper>) in the type KStream is not applicable for the arguments (new KeyValueMapper>(){})?
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Can you share your code and topology configuration? Basically, map should be applicable for KeyValueMapper, but without your code I can not find the issue.Yoav Naaman– Yoav Naaman2023-09-26 13:07:09 +00:00Commented Sep 26, 2023 at 13:07
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1 Answer
From http://docs.confluent.io/current/streams/developer-guide.html#stateless-transformations:
The example changes the value type from byte[] to Integer. For String to CarClass is would be the same.
KStream<byte[], String> stream = ...;
// Java 8+ example, using lambda expressions
// Note how we change the key and the key type (similar to `selectKey`)
// as well as the value and the value type.
KStream<String, Integer> transformed = stream.map(
(key, value) -> KeyValue.pair(value.toLowerCase(), value.length()));
// Java 7 example
KStream<String, Integer> transformed = stream.map(
new KeyValueMapper<byte[], String, KeyValue<String, Integer>>() {
@Override
public KeyValue<String, Integer> apply(byte[] key, String value) {
return new KeyValue<>(value.toLowerCase(), value.length());
}
});
However, if you want to only modify the value, I would recommend to use mapValues() instead of map().
