Since default maps want to fulfill this contract, they cannot return anything but null in the case of non-existent keys, which has been discussed in the Kotlin forum before.

Returns the value corresponding to the given, or null if such a key is not present in the map. The reason for this is the contract of the Map interface, which says: Instead, it provides a default value for unknown keys, which can be really helpful for grouping and counting algorithms like the following one: from collections import defaultdictĭata = The defaultdict can also be used with other types and makes sure that you don't get a KeyError when running your code. You can find the Python defaultdict documentation and some examples here but the basic use case is shown in the following snippet: from collections import defaultdict Kotlin also comes with a similar tool which I want to demonstrate in this little article. Have you ever used a default map or default dict before? If you know Python a bit, you probably saw its defaultdict in action at some point. We should note that the deleted value is also a String because JsonElement always saves its content as a String.By s1m0nw1 1 Comment Does Kotlin have a default Map? 'createdDate' to MapHelper.DATE_FORMAT.format(SERIALIZABLE_PROJECT.createdDate), Next, we can verify the result: val map = KotlinSerializationMapHelper.toMap(SERIALIZABLE_PROJECT) Is JsonObject -> jsonObjectToMap(element) If we want to match this behavior in our toMap function, we could add a filtering step: fun toMapWithOnlyPrimar圜onstructorProperties(obj: T): Map However, this string contains only the properties from the primary constructor: assertFalse(project.toString().contains(Project::description.name)) As we know, the default toString function of a data class will convert a data object to a string.

Kotlin map not null