When running spotbugs on a Kolin project I get errors such as:
[ERROR] Private method com.example.CSVRecord.component1() is never called [com.example.CSVRecord] In CSVRecord.kt UPM_UNCALLED_PRIVATE_METHOD
on classes such as:
data class CSVRecord(private val columns: SortedSet<CSVColumn>) : Iterable<String> {
override fun iterator(): Iterator<String> {
return columns.map { it.value }.iterator()
}
}
I'm not really clear where component1 came from!
According to the Data Classes documentation:
The compiler automatically derives the following members from all properties declared in the primary constructor:
- equals()/hashCode() pair;
- toString() of the form "User(name=John, age=42)";
- componentN() functions corresponding to the properties in their order of declaration;
- copy() function (see below).
This is one the features of data classes. The auto-generated componentN functions allow you to use Destructuring Declarations on this type of classes:
data class Result(val result: Int, val status: Status)
fun function(...): Result {
// computations
return Result(result, status)
}
// Now, to use this function:
val (result, status) = function(...)