Moshi Kotlin Codegen + R8 出現 parameter type is null

Moshi 是一個 JSON serialization/deserialization 的 library。和 Gson 不同的是它提供了 Kotlin Codegen，它可以生成 serialization/deserialization 的 adapter class，所以可以避免使用 reflection，而且 adapter 還會參照 Kotlin 的 non-null 和 default value。不過最近發現 production app 會出現 parameter type is null 的錯誤訊息。

java.lang.NoSuchMethodException: parameter type is null
    at java.lang.Class.getConstructor0(Class.java:2322)
    at java.lang.Class.getDeclaredConstructor(Class.java:2166)
    at net.swiftzer.metroride.remote.mtrupdate.status.LineStatusResponse_LineStatusJsonAdapter.a(LineStatusResponse_LineStatusJsonAdapter.kt:70)
    at net.swiftzer.metroride.remote.mtrupdate.status.LineStatusResponse_LineStatusJsonAdapter.a(LineStatusResponse_LineStatusJsonAdapter.kt:19)
    at f.d.a.t.a.a(NullSafeJsonAdapter.java:40)
    at f.d.a.d.a(CollectionJsonAdapter.java:76)
    at f.d.a.d$b.a(CollectionJsonAdapter.java:53)
    at f.d.a.t.a.a(NullSafeJsonAdapter.java:40)
    at net.swiftzer.metroride.remote.mtrupdate.status.LineStatusResponseJsonAdapter.a(LineStatusResponseJsonAdapter.kt:47)
    at net.swiftzer.metroride.remote.mtrupdate.status.LineStatusResponseJsonAdapter.a(LineStatusResponseJsonAdapter.kt:21)
    at f.d.a.t.a.a(NullSafeJsonAdapter.java:40)
    at q.z.a.c.a(MoshiResponseBodyConverter.java:45)
    at q.z.a.c.a(MoshiResponseBodyConverter.java:27)
    at q.m.a(OkHttpCall.java:225)
    at q.m.h(OkHttpCall.java:188)
    at q.y.a.c.b(CallExecuteObservable.java:45)
    at i.a.e.a(Observable.java:12268)
    at q.y.a.a.b(BodyObservable.java:34)
    at i.a.e.a(Observable.java:12268)
    at i.a.p.e.b.d.b(ObservableSingleSingle.java:35)
    at i.a.i.a(Single.java:3603)
    at i.a.p.e.c.b.b(SingleMap.java:34)
    at i.a.i.a(Single.java:3603)
    at i.a.p.e.c.e.b(SingleZipArray.java:63)
    at i.a.i.a(Single.java:3603)
    at i.a.p.e.c.b.b(SingleMap.java:34)
    at i.a.i.a(Single.java:3603)
    at i.a.p.e.c.d$a.run(SingleSubscribeOn.java:89)
    at i.a.h$a.run(Scheduler.java:578)
    at i.a.p.f.h.run(ScheduledRunnable.java:66)
    at i.a.p.f.h.call(ScheduledRunnable.java:57)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:301)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
    at java.lang.Thread.run(Thread.java:764)

Google 過才發現 R8 的問題。如果將 R8 改用 2.0.39 版就會變回正常。

buildscript {
    repositories {
        maven {
            url 'https://storage.googleapis.com/r8-releases/raw'
        }
    }

    dependencies {
        classpath 'com.android.tools:r8:2.0.39.         // Must be before the Gradle Plugin for Android.
        classpath 'com.android.tools.build:gradle:X.Y.Z' // Your current AGP version.
    }
}

效果：

參考

註

現在（2020 年 4 月 26 日）的 R8 版本應該沒有這個問題。

參考#

註#

參考

註