Default interface methods are only supported starting with Android N

[ArcherEmiya05]

ExoPlayer version:
implementation 'com.google.android.exoplayer:exoplayer:2.9.2'

Issue:
While rebuilding the app I encountered so many deprecated code as expected so I refactor it but now I am getting this new error:
Error: Default interface methods are only supported starting with Android N (--min-api 24): void com.google.android.exoplayer2.Player$EventListener.onSeekProcessed().

Codes Before:

private final Player.EventListener eventListener = new Player.DefaultEventListener(){
@OverRide
public void onPlayerStateChanged(boolean playWhenReady, int playbackState) {
switch (playbackState){
//Buffer after doing forward,backward, or seek
case Player.STATE_BUFFERING:
break;
//Ready when it starts playing or start/stop is clicked
case Player.STATE_READY:
break;
//Idle after calling error or still no internet connection after doing forward,backward, or seek
case Player.STATE_IDLE:
//Save the last seek position
saveLastPosition();
createPlayers();
break;
//Ended if the streaming is finish
case Player.STATE_ENDED:
playerView.showController();
break;
}

//Since isRepeating is only true in RecyclerView this will not be triggered unless Player is hosted by Activity
if (!isRepeating)
EventBus.getDefault().post(new UpdateOption(itemPosition));
}

Then it says @deprecated Use {@link EventListener} interface directly for selective overrides as all methods are implemented as no-op default methods. so I update it to this

private final Player.EventListener eventListener = new Player.EventListener(){
@OverRide
public void onPlayerStateChanged(boolean playWhenReady, int playbackState) {
switch (playbackState){
//Buffer after doing forward,backward, or seek
case Player.STATE_BUFFERING:
break;
//Ready when it starts playing or start/stop is clicked
case Player.STATE_READY:
break;
//Idle after calling error or still no internet connection after doing forward,backward, or seek
case Player.STATE_IDLE:
//Save the last seek position
saveLastPosition();
createPlayers();
break;
//Ended if the streaming is finish
case Player.STATE_ENDED:
playerView.showController();
break;
}

//Since isRepeating is only true in RecyclerView this will not be triggered unless Player is hosted by Activity
if (!isRepeating)
EventBus.getDefault().post(new UpdateOption(itemPosition));
}

@OverRide
public void onPositionDiscontinuity(int reason) {
if (player.getPlaybackError() != null) {
//The user has performed a seek whilst in the error state. Update the resume position so
//that if the user then retries, playback resumes from the position to which they seek.
position = Math.max(0, player.getContentPosition());
}
}

};

[ojw28]

You need to add

compileOptions {
    targetCompatibility JavaVersion.VERSION_1_8
}

to your build.gradle files, as described in the developer guide. You can refer to the ExoPlayer demo app for an example (and also confirm that it compiles fine, despite having minSdkVersion 16.

[AndroidDeveloperLB]

@ojw28 This didn't work for me. I've even tested on the Canary build of the IDE, and on a sample project that doesn't even use ExoPlayer, and it doesn't even work if the minSdk is 24 . See here:

https://youtrack.jetbrains.com/issue/KT-29138

In my case, I wanted to use this:

 player!!.addListener(object : Player.EventListener {
                    override fun onPositionDiscontinuity(reason: Int) {
                        super.onPositionDiscontinuity(reason)
                        Log.d("AppLog", "onPositionDiscontinuity: reason : $reason currentWindowIndex: ${player?.currentWindowIndex}")
                    }
                })

But I still got this error.
Please fix this issue.

[tonihei]

I needed to set the Kotlin JVM version in the Android Studio settings to get that to work.
File -> Settings -> Other Settings -> Kotlin Compiler -> Target JVM version. The default in my Android Studio is 1.6. but should be 1.8.

[AndroidDeveloperLB]

@tonihei Then it's not enabled by default, doesn't tell to change it, and doesn't offer this fix.

Also, after changing it, it didn't help. I tried to re-build the project. Didn't help. Still got the error.
Restarting the IDE also didn't help.

On the sample project, it only seemed to be fine as it doesn't mark the error on the textual editor of the Kotlin file, but on the large one it showed it. However, when trying to launch the sample, it failed with this error. How could it be?

Here's how it looks on the sample project:

Attached a sample project, where it works fine, and a screenshot of the large one...

ExoPlayerTest.zip

[tonihei]

Unfortunately, we can't help you debug your app. Given that it works fine in a small example suggests that it works in principle and something else in your larger project is misconfigured. This kind of question is better posted in StackOverflow or similar sites.

We'll update our docs to note how the configuration for Kotlin looks like.

[AndroidDeveloperLB]

@tonihei It only visually works on the ExoPlayer sample I've made (doesn't mark the line with an error). When trying to build&run, it gave an error. Please check the updated post.

So it doesn't matter if it's on the large project or the sample. On both it didn't work.

Please explain what I should do.

[tonihei]

On the sample project, it seemed to fine as it doesn't mark the error, but on the large one it showed it.

Doesn't that say that it works on the sample project?

[AndroidDeveloperLB]

No. Look at the screenshot. It clearly shows that I can't build&run the project because of it. It just doesn't mark the line.

Only when I remove the call to "super...", it works perfectly fine, both visually and when trying to build&run.

[AndroidDeveloperLB]

Here, I've made a video for you to understand:

2019-01-07_12-40-52.zip

Please talk to the Kotlin or Android-Studio guys (or IntelliJ). It's a problem that will exist not just for ExoPlayer...

[tonihei]

It works perfectly fine for a fresh Kotlin project using ExoPlayer and the listener call as in your example in Android Studio 3.2.1. I'd suggest copying parts of your code to a new project to see at which point it goes wrong.

[tonihei]

Aside: There is no point in calling super for a default interface implementation because these are not meant to be called anyway and are only there for interface implementations which don't override the methods themselves. As soon as you provide your own implementation for a method, you shouldn't call into the default interface implementation.

[AndroidDeveloperLB]

So the IDE auto-completes the call to "super" for the wrong reason?
When you say "these are not meant to be called", does it mean they can't be called in general, or just on this specific case of ExoPlayer?
In general, is the default implementation (on Kotlin and Java) available only in case you don't override them? It won't run in case you override them?

Also, what exactly works? With, or without the call to the "super" ? Can you please share a sample project with this listener?

[tonihei]

When you say "these are not meant to be called", does it mean they can't be called in general, or just on this specific case of ExoPlayer?

That depends on how you use them. A common interpretation is to use them as a fallback if no other implementation is provided and you therefore shouldn't call them directly from a subclass (that's what we do in ExoPlayer). But of course the language allows to call them and it's unclear how the IDE should implement that correctly.

[AndroidDeveloperLB]

So the IDE is fine when it suggests it, then, just like in similar cases. In general, the default implementation should be called in some cases, which might not always be clear for people who use the interface.

But why does it show an error ? Can you please share me your sample project? I want to know what causes it, and if your sample project would produce the same issue.

Is it ok on ExoPlayer, at least, not to ever call "super" here? I think the Listener doesn't need a default implementation anyway. It's just a nice replacement to a normal interface, so that we won't have to create multiple empty implementations, one for each function...

[tonihei]

Is it ok on ExoPlayer, at least, not to ever call "super" here?

Yes, it is. The default implementations are all empty anyway.

[AndroidDeveloperLB]

Yes I know, but technically they might still not be empty in the future. I mean to ask if it will always be this way.

[tonihei]

Yes, pretty sure. And even if not, we will never oblige an implementation to call the default super method in an interface.

[AndroidDeveloperLB]

I see. Can you please send me a sample nevertheless? One that does call "super" and yet builds&runs fine for you?

[tonihei]

That's my project. More or less the auto-generated example project with ExoPlayer dependency.
public_exoplayer.zip

[AndroidDeveloperLB]

I can see you've added this, which wasn't added automatically by any of the settings screens of the IDE:

    kotlinOptions {
        jvmTarget = JavaVersion.VERSION_1_8
    }

Adding it fixed the issue completely. Please tell whoever's in charge about this.

[tonihei]

That's the equivalent of the Settings option in gradle. Both worked for me.

[AndroidDeveloperLB]

I don't know. Nothing on the IDE has added it so far, and I'm using the Canary build of it. I had to add it manually.

Maybe you've created a new project and it added it for you. On the current projects, it doesn't do it. Not even on the sample project that I've sent you, which isn't that old.

[AndroidDeveloperLB]

Say, is there a way in Kotlin/Java, to mark an interface easily that all of its functions are set to be "default" with empty implementation?
Currently I think that on Java you have to add "default" for each function and "{}" , and on Kotlin you have to add only "{}". But for both you have to do it for each function.

I've requested something similar in the past, here:

https://youtrack.jetbrains.com/issue/KT-22827

[zishanj]

I am also facing this issue in my Android Java app even I have added targetCompatibility JavaVersion.VERSION_1_8

[tonihei]

See commit above for how to configure Kotlin to use Java 8 features.

Closing this issue now as the doc has been updated.

[zishanj]

@tonihei as I have mentioned, my issue is Java related not Kotlin.

[zishanj]

I have added these both lines in my Java app as mentioned in doc:

sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8

but its still throwing this error.

[ALi-Moslehi]

hi, i added

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

but not work.

Error: Static interface methods are only supported starting with Android N (--min-api 24):

java.lang.Object com.google.android.exoplayer2.analytics.AnalyticsListener.access$super(com.google.android.exoplayer2.analytics.AnalyticsListener, java.lang.String, java.lang.Object[])

[AndroidDeveloperLB]

@ALi-Moslehi Try as such instead:

compileOptions {
    sourceCompatibility = 1.8
    targetCompatibility = 1.8
}