kotlin : toJson return null

[zhaoxiong123]

`
val gson = Gson()

        data class TestModel(
            val id: Int,
            val description: String
        )

        val jsonString = gson.toJson(TestModel(1,"Test"))

        println(jsonString)

`
why jsonString is null ?
who knows ?
my kotlin version is 1.4.10.
my jdk version is 1.8

[yerlikayao]

Gson doesn't support serializing anonymous types.

https://stackoverflow.com/questions/39538677/why-does-gson-tojson-always-return-null

[Richyeoh]

我测试了一下，匿名类或者局部类都会有这个问题。
可能Kotlin不支持吧。

[Marcono1234]

As mentioned above, most likely Gson's default behavior for anonymous and local classes caused the null return value.

However, in the latest Gson versions this might actually be fixed for local Kotlin data classes due to #1969.