ClassCastException kotlin.coroutines.intrinsics.CoroutineSingletons cannot be cast to java.util.List

[vtoupet]

Current behavior

I am trying to access async storage from Java (i.e. Brownfield integration ->I implemented a widget in Java). I've followed the guide to read values

void readStorageValue(Context ctx, String key) {
    AsyncStorageAccess asyncStorage = StorageModule.getStorageInstance(ctx);

    BuildersKt.launch(GlobalScope.INSTANCE,
            Dispatchers.getIO(),
            CoroutineStart.DEFAULT,
            (scope, continuation) -> {
                List<String> keys = new ArrayList<>();
                keys.add(key);

                List<Entry> entries = (List<Entry>) asyncStorage.getValues(keys, (Continuation<? super List<? extends Entry>>) continuation);
                doSomethingWithValues(entries);

                return Unit.INSTANCE;
            });

}

When readStorageValue method gets called, my application crashes: ClassCastException kotlin.coroutines.intrinsics.CoroutineSingletons cannot be cast to java.util.List

Expected behavior

The application should not crash

Repro steps

Environment

• Platforms tested:
  • Android
  • iOS
  • macOS
  • Windows
• AsyncStorage version: 1.15.1
• Environment:
  System:
  OS: macOS 11.2.3
  CPU: (8) x64 Intel(R) Core(TM) i7-4770HQ CPU @ 2.20GHz
  Memory: 66.86 MB / 16.00 GB
  Shell: 5.8 - /bin/zsh
  Binaries:
  Node: 15.11.0 - /usr/local/bin/node
  Yarn: 1.22.10 - /usr/local/bin/yarn
  npm: 7.6.0 - /usr/local/bin/npm
  Watchman: 4.9.0 - /usr/local/bin/watchman
  Managers:
  CocoaPods: 1.10.1 - /usr/local/bin/pod
  SDKs:
  iOS SDK:
  Platforms: iOS 14.4, DriverKit 20.2, macOS 11.1, tvOS 14.3, watchOS 7.2
  Android SDK: Not Found
  IDEs:
  Android Studio: 4.1 AI-201.8743.12.41.7199119
  Xcode: 12.4/12D4e - /usr/bin/xcodebuild
  Languages:
  Java: 15.0.2 - /usr/bin/javac
  npmPackages:
  @react-native-community/cli: Not Found
  react: 17.0.1 => 17.0.1
  react-native: 0.64.0 => 0.64.0
  react-native-macos: Not Found
  npmGlobalPackages:
  react-native: Not Found

Kotlin version 1.4.32

• Logs/Errors that may be relevant:

java.lang.ClassCastException: kotlin.coroutines.intrinsics.CoroutineSingletons cannot be cast to java.util.List
    at com.vtoupet.smartmixin.utils.Storage.lambda$readStorageValue$0(Storage.java:43)
    at com.vtoupet.smartmixin.utils.-$$Lambda$Storage$DXdrLrbhpt1sIvFEJaj9B7vmyWg.invoke
    at kotlin.coroutines.intrinsics.IntrinsicsKt__IntrinsicsJvmKt$createCoroutineUnintercepted$$inlined$createCoroutineFromSuspendFunction$IntrinsicsKt__IntrinsicsJvmKt$4.invokeSuspend(IntrinsicsJvm.kt:205)
    at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
    at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:106)
    at kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.kt:571)
    at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.executeTask(CoroutineScheduler.kt:750)
    at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.runWorker(CoroutineScheduler.kt:678)
    at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:665)

[vtoupet]

@krizzu did you make the Java code provided in the documentation work? Any idea why I am getting this error?

Do you need additional information ?

[krizzu]

@vtoupet hey,

That's right, this example is out of date, since I made all storage methods suspend as the last step, sorry.
I still recommend accessing storage through Kotlin.

Here's updated way of how you can access storage from Java:

        BuildersKt.launch(GlobalScope.INSTANCE,
                Dispatchers.getIO(),
                CoroutineStart.DEFAULT,
                (scope, continuation) -> {
                    List<String> keys = new ArrayList<>();
                    keys.add("kkk");

                    Continuation<? super List<? extends Entry>> cont = new Continuation() {
                        @NotNull
                        @Override
                        public CoroutineContext getContext() {
                            return scope.getCoroutineContext();
                        }

                        @Override
                        public void resumeWith(@NotNull Object o) {
                            List<Entry> entries = (List<Entry>) o;
                            doSomethingWithEntries(entries);
                        }
                    };

                    asyncStorage.getValues(keys, cont);
                    return Unit.INSTANCE;
                });

It's a nice opportunity to contribute to docs, if you're interested. Here's updated version of how you can save data to storage on Java:

        BuildersKt.launch(GlobalScope.INSTANCE,
                Dispatchers.getIO(),
                CoroutineStart.DEFAULT,
                (scope, continuation) -> {
                    List<String> keys = new ArrayList<>();
                    keys.add("kkk");

                    Continuation cont = new Continuation() {
                        @NotNull
                        @Override
                        public CoroutineContext getContext() {
                            return scope.getCoroutineContext();
                        }

                        @Override
                        public void resumeWith(@NotNull Object o) {}
                    };

                    List<Entry> entries = new ArrayList<>();
                    Entry entry = new Entry("my_key", "my_value");
                    entries.add(entry);
                    asyncStorage.setValues(entries, cont);
                    return Unit.INSTANCE;
                });

[vtoupet]

Thanks @krizzu. Sure I will send a PR with the updated docs.

[vtoupet]

@krizzu I've just submitted a PR #583 with the updated doc

[krizzu]

Thanks, I'm going to close this issue then