gerrenta.blogg.se - Kotlin map not null

It’s not “well-behaved.” And yet, it was working fine up till now. How does Gson handle poorly-behaved classes?īut this data class doesn’t have a no-args constructor.

Doesn’t matter whether public or private.

Well-behaved classes that are meant for serialization and deserialization should have a no-argument constructor. While deserializing an Object, Gson needs to create a default instance of the class. Well, let’s step back and ask: How did this work in the first place, when we didn’t encounter bogus data? Gson’s docs on “Writing an Instance Creator” say: If you slurp in, Gson will apparently poke a null value into your not-null field.

While deserializing, a missing entry in JSON results in setting the corresponding field in the object to its default value: null for object types, zero for numeric types, and false for booleans.

While serializing, a null field is omitted from the output.

This implementation handles nulls correctly. Gson makes slurping in JSON as objects painless. There’s one more actor in this drama: Gson. Nope, it was Retrofit2’s little helper: Gson.

And, indeed, the corresponding field proved to be missing from the API response.īut why did this not error out at that point? How did an Invitation ever get created with a null placeName property in the first place? Kotlin told us that would be impossible, but exception logging doesn’t lie.

So the bogus data probably came from there.

How does a not-null property wind up null? The exception that shouldn’t have been possible had left the database locked, and ultimately, the app had crashed. While I might personally prefer sticking with null-safe calls and elvis operators, it sounds like you'd prefer cleaner code at the call site (especially considering you know these keys exist and have associated non-null values).E/AndroidRuntime: FATAL EXCEPTION: pool-2-thread-2Ī: database is locked (code 5): retrycount exceeded MapOf() is providing a Map with no guarantees for the presence of a key- something which is kind of expected especially considering the Java implementation of Map.