Gson ignore null when deserializing object

Question

I want to deserialize a json string that containts a null value in Java. I want to deserialize the object to a Properties object. The json string is something l

Answer 1

We have this solution:

1. All of your data classes need to extends abstract class

abstract class PoJoClass

2. Create this safe deserializer to delete nulls from JSON

class SafeDeserializer(private val gson: Gson) :JsonDeserializer {
    override fun deserialize(json: JsonElement?, typeOfT: Type?, context: JsonDeserializationContext?): T {

        val jsonObject = json as JsonObject
        removeNullsFromJson(jsonObject)
        return gson.fromJson(jsonObject, typeOfT)
    }

    private fun removeNullsFromJson(jsonObject: JsonObject) {
        val iterator = jsonObject.keySet().iterator()

        while (iterator.hasNext()) {
            val key = iterator.next()
            when(val json = jsonObject[key]){
                is JsonObject -> removeNullsFromJson(json)
                is JsonNull -> iterator.remove()
            }
        }
    }
}

3. And register it in your GSON instance

val gson = Gson().newBuilder()
                .registerTypeHierarchyAdapter(PoJoClass::class.java, SafeDeserializer(Gson()))
                .create()