MediaBrowserServiceCompat无法绑定到服务

Question

我的代码非常简单,我只想使用MediaBrowserServiceCompat绑定到音乐服务,实际上我有一个更大的程序有同样的问题,所以我试图做一个较小的没有所有不重要的部分,我得到以下错误:

08-27 11:31:30.848 12214-12214/com.example.android.newcheck E/AndroidRuntime:FATAL EXCEPTION:main进程:com.example.android.newcheck,PID:12214 java.lang.RuntimeException:无法绑定到使用Intent服务com.example.android.newcheck.MusicStreamService@8c043ff {act = android.media.browse.MediaBrowserService cmp = com.example.android.newcheck/.MusicStreamService}:java.lang.NullPointerException:尝试调用接口方法' android.os.IBinder android.support.v4.media.MediaBrowserServiceCompat $ MediaBrowserServiceImpl.onBind(android.content.Intent)'在android.app.ActivityThread.handleBindService(ActivityThread.java:3847)的空对象引用上android.app .ActivityThread.access $ 2200(ActivityThread.java:221)在android.app.Aoo运行android.app.Handler.dispatchMessage(Handler.java:102)的android.app.ActivityThread $ H.handleMessage(ActivityThread.java:1887) .loop(Looper.java:158)在java.lang.reflect.Method.inv的android.app.ActivityThread.main(ActivityThread.java:7224)在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:1230)的com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)中的oke(Native Method)引起:java. lang.NullPointerException:尝试在android.support.v4.media上的空对象引用上调用接口方法'android.os.IBinder android.support.v4.media.MediaBrowserServiceCompat $ MediaBrowserServiceImpl.onBind(android.content.Intent)'. MediaBrowserServiceCompat.onBind(MediaBrowserServiceCompat.java:613)位于android.app.ActivityThread.access上的android.app.ActivityThread.handleBindService(ActivityThread.java:3834)$ 2200(ActivityThread.java:221),android.app.ActivityThread $ H. handleMessage(ActivityThread.java:1887)位于android.app.AtoT.Thread.main上的android.os.Handler.dispatchMessage(Handler.java:102)android.os.Looper.loop(Looper.java:158)(ActivityThread.java) :7224)at com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:12)中的java.lang.reflect.Method.invoke(Native Method)30)在com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120) 

我主要在youtube上使用伊恩湖讲座并做了他说的所有事情,但我不知道为什么我得到这个错误,我试图在网上找到答案,但找不到任何答案.谢谢您的帮助.

AndroidManifest:

    <service
        android:name=".MusicStreamService"
        android:exported="true">
        <intent-filter>
            <action android:name="android.media.browse.MediaBrowserService" />
        </intent-filter>
    </service>

主要活动:

    @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    MediaBrowserCompat mediaBrowser = new MediaBrowserCompat(MainActivity.this, new ComponentName(MainActivity.this, MusicStreamService.class),
            new MediaBrowserCompat.ConnectionCallback() {
                @Override
                public void onConnected() {
                    Log.v("MainActivity","connected");
                }
                @Override
                public void onConnectionSuspended() {
                    super.onConnectionSuspended();
                }
                @Override
                public void onConnectionFailed() {
                    super.onConnectionFailed();
                }
            }, null);
    mediaBrowser.connect();
    Button click = (Button) findViewById(R.id.button);
    click.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            startService(new Intent(MainActivity.this, MusicStreamService.class));
        }
    });
}

MusicStreamService:

public class MusicStreamService extends MediaBrowserServiceCompat {
@Nullable
@Override
public BrowserRoot onGetRoot(@NonNull String clientPackageName, int clientUid, @Nullable Bundle rootHints) {
    Log.v("***********", "getroot");
    return new BrowserRoot(getString(R.string.app_name), // Name visible in Android Auto
            null); // Bundle of optional extras
}

@Override
public void onLoadChildren(@NonNull String parentId, @NonNull Result<List<MediaBrowserCompat.MediaItem>> result) {
    Log.v("*********", "one step before connect2");
    result.sendResult(null);
}

@Override
public void onCreate() {
    MediaSessionCompat mediaSession = new MediaSessionCompat(this, MusicStreamService.class.getSimpleName());
    setSessionToken(mediaSession.getSessionToken());
    mediaSession.setFlags(MediaSessionCompat.FLAG_HANDLES_MEDIA_BUTTONS |
            MediaSessionCompat.FLAG_HANDLES_TRANSPORT_CONTROLS);
    mediaSession.setActive(true);
}

Answer 1

我忘了在MusicStreamService类的onCreate方法中编写super.onCreate().解决了.