Issue in Type Converter of Room Database Kotlin - kotlin

Question

Type Convertor Class :
class ProductTypeConvertor {
var gson = Gson()
#TypeConverter
fun foodRecipeToString(foodRecipe: ProductList): String {
return gson.toJson(foodRecipe)
}
#TypeConverter
fun stringToFoodRecipe(data: String): ProductList {
val listType = object : TypeToken<ProductList>() {}.type
return gson.fromJson(data, listType)
}
#TypeConverter
fun resultToString(result: Products): String {
return gson.toJson(result)
}
#TypeConverter
fun stringToResult(data: String): Products {
val listType = object : TypeToken<Products>() {}.type
return gson.fromJson(data, listType)
}
#TypeConverter
fun stringToVListServer(data: String?): List<Variants?>? {
if (data == null) {
return Collections.emptyList()
}
val listType: Type = object :
TypeToken<List<Variants?>?>() {}.type
return gson.fromJson<List<Variants?>>(data, listType)
}
#TypeConverter
fun VlistServerToString(someObjects: List<Variants?>?): String? {
return gson.toJson(someObjects)
}
#TypeConverter
fun stringToListServer(data: String?): List<String?>? {
if (data == null) {
return Collections.emptyList()
}
val listType: Type = object :
TypeToken<List<String?>?>() {}.type
return gson.fromJson<List<String?>>(data, listType)
}
#TypeConverter
fun listServerToString(someObjects: List<String?>?): String? {
return gson.toJson(someObjects)
}
}
Product Entity :
#ColumnInfo(name = "other_images")
var other_images: ArrayList<String> = arrayListOf(),
#ColumnInfo(name = "variants")
var variants : ArrayList<Variants> = arrayListOf()
Error :
error: incompatible types: List cannot be converted to ArrayList
_tmpVariants = __productTypeConvertor.stringToVListServer(_tmp_3);
error: incompatible types: List cannot be converted to ArrayList
_tmpOther_images = __productTypeConvertor.stringToListServer(_tmp);

Answer 1

The types do no match it's like the anecdotal apples(List type) and oranges(ArrayList type).
Either use ArrayList or List as both
a) the column type and
b) as the input parameter and the result from the converters.