How to handle errors thrown within AudioHandler implementations?-CodePudding

For the sake of the argument let's say I have an implementation of BaseAudioHandler in my application:

class AudioPlayerHandler extends BaseAudioHandler {

    @override
    Future<void> play() async {
      throw Error();
    }

}

Then when I call this function from an event handler:

void onPlayButtonTap() {
    try {
        audioPlayerHandler.play();
    } catch (error) {
        // Error is not caught, but in the console I see unhandled error message.
        print(error.toString())
    } 
}

It doesn't catch the error thrown within the method.

Of course the example this way doesn't make sense, but I've run into this problem when trying to load an invalid url which i could not handle in 'regular' way.

[VERBOSE-2:dart_vm_initializer.cc(41)] Unhandled Exception: Instance of 'Error'
#0      AudioPlayerHandler.play (package:audio_service_example/main.dart:197:5)
#1      MainScreen._button.<anonymous closure> (package:audio_service_example/main.dart:145:22)
#2      _InkResponseState.handleTap (package:flutter/src/material/ink_well.dart:1072:21)
#3      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:253:24)
#4      TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:627:11)
#5      BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:306:5)
#6      BaseTapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:239:7)
#7      PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:615:9)
#8      PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:98:12)
#9      PointerRouter._dispatchEventToRoutes.<anonymous closure> (package:flutter/src/gestures/pointer_ro<…>

I expected to be able to use a try-catch block to handle the error.

I can handle the error inside the audiohandler implementation and let's say I can propagate a custom event that tells the user of the handler that an error occured, but that solution seems to be a bit clumsy.

I'm also not sure if this is a dart programming language quirk unknown to me or an implementation problem? Tried to step through with debugger but did not find anything meaningful.

Could you please help me how this error handling should work?

Thanks you in advance!

CodePudding user response：

This concerns the Dart language.

Because you defined play as an async method, play doesn't actually throw an error. It returns a future which evaluates to an error. If you await that future, you'll be able to catch the error:

    try {
        await audioPlayerHandler.play();