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kotlinlang

I have case where i need to find all duplicates in list by code and finally get values from duplicateList with lower dateTime.
Any ideas?
```
fun main() {
      val fileList = listOf&lt;FileName&gt;()
}

data class FileName(val code: String, val uid: String, val dateTime: LocalDateTime)
```

Does `distinctBy` do what you need?
<https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/distinct-by.html>

I need to do the opposite, get only duplicate codes :slightly_smiling_face:

```
list.groupingBy { it.key }
  .eachCount()
  .filterValues { it &gt; 1 }
```

that gives you all the duplicate keys as keys in the map. You can do `.keys` if you need them as a separate collection