Multi tool use

Android kotlin Object Any type mismatch

How to assign kotlin map to java library map.
This gives type mismatch error for Object and Any.

I need to assign java map variable in a 3rd party java library, from my kotlin code map.

val model = JavaModel() //from 3rd party java library

val params:MutableMap<String, Any> = HashMap()
params.put("key","value")
model.params = params //gives error below


Type mismatch: inferred type is MutableMap<String, Any> but Map<String, Object>? was expected

MutableMap<String, Any>

Map<String, Object>?

JavaModel

params

3 Answers
3

Java's Object is not the same as Kotlin's Any, so the type MutableMap<String, Any> and Map<String, Object>? mismatched, because you cannot change the 3rd party java library, just declare the params as:

Object

Any

MutableMap<String, Any>

Map<String, Object>?

params

val params: MutableMap<String, Object> = HashMap()


var param: MutableMap<String, Object?> = hashMapOf(); param.put("key", "")

JavaModel

JavaModel.paramsrequires explicitly <String, Object>. You cannot use Kotlin Any there. Also HashMap in Kotlin is mapped type so your best shot is to do simple workaround:

JavaModel.params

<String, Object>

Any

HashMap

Extend HashMap from java, ex. ParamsMap.java:

ParamsMap.java

public class ParamsMap extends HashMap<String, Object> { }


And use it like this:

val model = JavaModel()

val params = ParamsMap()
params.put("key","value")
model.params = params


The only thing I can achieve this is to create a new Java class and do the operation inside it. I give the params Java Map as parameter and and I made the operation inside the Java class.

Kotlin automatically behaves any Object as Any so it gives type mismatch for the assignment.

public class ObjectMapper {
public static void setParam(Map<String, Object> params, String key, String value) {
params.put(key, value);
}
}


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