I have a strange problem. ```@Parcelize data class Post( @SerializedName("topic_list") val topics: M...

# android

[haoxiqiang]

I have a strange problem.

@Parcelize
data class Post(
@SerializedName("topic_list")
val topics: MutableList<Topic> = mutableListOf(),
@SerializedName("tag_list")
val tagList: MutableList<PostTag> = mutableListOf()
)

I build a android project with the kotlin-parcelize, if json with out topic_list/tag_list, I think it will be the default value which two empty list.
but in last week. it’s generate by kapt without default value.
after decompile:

@SerializedName("media_list")
    @NotNull
    private List<Media> mediaList;

Why….😅

[Tim Oltjenbruns]

So you mention JSON and Parcelize together, and I’m getting confused. I didn’t think those two were related.

[Tim Oltjenbruns]

So set me straight here - we are definitely talking about Parcels and not json right?

[haoxiqiang]

yeah, now the data class post will failed when parcel write the topic list, because it generated with @NotNull but with init value.
I want to get the real reason.

[haoxiqiang]

sorry, i have decompile the diff version. the parcelize generate the same code. It’s may be the gson config problem. I’ll find out why.

[Tim Oltjenbruns]

I guess its possible that if Parcelize was giving you default values, that would affect Gson!

[haoxiqiang]

In the weekend, i have find the reason. the gson library use an unsafe operator to create a obj.
some related:
https://github.com/google/gson/issues/1657
https://github.com/google/gson/issues/1550
https://github.com/google/gson/issues/1444

in consideration of the kotlin null/no-null is a very clear define. the gson is a bad impl.

It took me an hour to switch to moshi. kotln frindly is important.

[haoxiqiang]

A parameterless constructor must be provided. If not, the gson will use a unsafe new instance api.

[haoxiqiang]

// is OK
data class A (
@SerializedName(“a”)
val a:String=“”,
@SerializedName(“b”)
val b:Int=0
)

// is Failed
data class A (
@SerializedName(“a”)
val a:String,
@SerializedName(“b”)
val b:Int=0
)