Converting a HashMap using moshi

Question

I'm trying to convert a HashMap of elements into a JSON string. I'm using the method used in this link.

 val elementsNew: HashMap<String, Element> = HashMap(elements)
 val type = Types.newParameterizedType(Map::class.java, String::class.java, Element::class.java)
 var json: String = builder.adapter(type).toJson(elementsNew)

But this gives the following error

Error:(236, 40) Type inference failed: Not enough information to infer parameter T in fun adapter(p0: Type!): JsonAdapter! Please specify it explicitly.

Can any one tell me where's the fault? Is it because of Kotlin?

worth noting that it's not exactly because of Kotlin. In Java, you'd end up with JsonAdapter<Object> (wouldn't be able to use that for your Map<String, Element> type). Kotlin forces you to provide the parameterizing arguments, so you can see the mistake sooner. — Eric Cochran

Egor Egor · Accepted Answer · 2017-12-15T11:37:46

Looking at the signature of the adapter() method, it can't infer its type parameter from the argument:

public <T> JsonAdapter<T> adapter(Type type)

Hence you have to provide the type explicitly:

var json = builder.adapter<Map<String, Element>>(type).toJson(elementsNew)

or alternatively:

val adapter: JsonAdapter<Map<String, Element>> = builder.adapter(type)
var json = adapter.toJson(elementsNew)

Converting a HashMap using moshi

1 Answers