MongoDB getList("field-name", Double::class.java); produces ClassCastException in Kotlin

user_5803704 0
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I'm trying to retrieve a field containing an array of Double from MongoDB, but I'm receiving a 

ClassCastException: List element cannot be cast to double.

The class is written in Kotlin, and the part of the code that produces the exception is: 

val coordinates = doc.getList(FIELD_COORDINATES, Double::class.java)

This works: 

val coordinates = doc.get(FIELD_COORDINATES) as List<Double>

And the equivalent code in Java works too: 

final List<Double> coordinates = doc.getList(FIELD_COORDINATES, Double.class);

enter image description here

Please let me know if this is a bug in Kotlin or there's a mistake in my code.

kotlin mongodb java
2 Answers

The equivalent of Double::class.java in Java is double.class, not Double.class. That would be written as java.lang.Double::class.java in Kotlin, or Double::class.javaObjectType.

alexey_r_92040

The answer of Alexey is correct. Here is an example how it should look like:

val coordinates = doc.getList("coordinates", Double::class.javaObjectType)

Notice the use of the Java ObjectType of Double.

user_11519830
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