Question

I want to copy one primitve property from one JsonObject to another

JsonObject propertyToBeCopied = source.getAsJsonObject(propertyName);

but I always run into this exception:

com.google.gson.JsonNull cannot be cast to com.google.gson.JsonObject

According to the documentation it should be possible to do the cast, or am I wrong?

Answer 1

According to the docsJsonNull is a JsonElement but not a JsonObject (which is itself a JsonElement). Using

JsonElement element = source.get(propertyName);
if (!(element instanceof JsonNull)) {
    JsonObject propertyToBeCopied = (JsonObject) element;
}

would return a JsonElement that is cast to JsonObject if it is not of the type JsonNull.