Question

我写这个是因为当我从sdCard中选择音频时遇到问题，我尝试用MediaPlayer播放它。

以下是我的代码的一部分：

Intent intent = new Intent();
intent.setType("audio/*");
intent.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(Intent.createChooser(intent,"Selecciona la música de Fondo "), PETICION_ESCOGER_AUDIO);


protected void onActivityResult(int requestCode, int resultCode, Intent data) 
{
    super.onActivityResult(requestCode, resultCode, data);
    musicaDeFondo.reset();
    if (requestCode == PETICION_ESCOGER_AUDIO)
    {

        Uri musicaFondoSeleccion = data.getData();
        if (musicaFondoSeleccion != null)
        {
            System.out.println(musicaFondoSeleccion.toString());
            // Here fails
            musicaDeFondo = (AndroidMusica) sonidoManager.nuevaMusicaSDCARD(Piano.this, musicaFondoSeleccion); // Here fails

        }

    }
}

我的AndroidMusica类构造函数：

public AndroidMusica (Context ctx, Uri path){
    try {
        mediaPlayer.setDataSource(ctx, path);  // Here files. line 37
        mediaPlayer.prepareAsync();
        isPrepared = true;
        mediaPlayer.setOnCompletionListener(this);
    } catch (IllegalStateException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

日志：

02-19 02:31:24.792: E/AndroidRuntime(19447): FATAL EXCEPTION: main
02-19 02:31:24.792: E/AndroidRuntime(19447): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=42, result=-1, data=Intent { dat=content://media/external/audio/media/434 }} to activity {com.psdmple.piano/com.psdmple.piano.Piano}: java.lang.NullPointerException
02-19 02:31:24.792: E/AndroidRuntime(19447):    at android.app.ActivityThread.deliverResults(ActivityThread.java:2997)
02-19 02:31:24.792: E/AndroidRuntime(19447):    at android.app.ActivityThread.handleSendResult(ActivityThread.java:3040)
02-19 02:31:24.792: E/AndroidRuntime(19447):    at android.app.ActivityThread.access$1100(ActivityThread.java:128)
02-19 02:31:24.792: E/AndroidRuntime(19447):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1191)
02-19 02:31:24.792: E/AndroidRuntime(19447):    at android.os.Handler.dispatchMessage(Handler.java:99)
02-19 02:31:24.792: E/AndroidRuntime(19447):    at android.os.Looper.loop(Looper.java:137)
02-19 02:31:24.792: E/AndroidRuntime(19447):    at android.app.ActivityThread.main(ActivityThread.java:4517)
02-19 02:31:24.792: E/AndroidRuntime(19447):    at java.lang.reflect.Method.invokeNative(Native Method)
02-19 02:31:24.792: E/AndroidRuntime(19447):    at java.lang.reflect.Method.invoke(Method.java:511)
02-19 02:31:24.792: E/AndroidRuntime(19447):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:993)
02-19 02:31:24.792: E/AndroidRuntime(19447):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:760)
02-19 02:31:24.792: E/AndroidRuntime(19447):    at dalvik.system.NativeStart.main(Native Method)
02-19 02:31:24.792: E/AndroidRuntime(19447): Caused by: java.lang.NullPointerException
02-19 02:31:24.792: E/AndroidRuntime(19447):    at logica.AndroidMusica.<init>(AndroidMusica.java:37)
02-19 02:31:24.792: E/AndroidRuntime(19447):    at logica.SonidoManager.nuevaMusicaSDCARD(SonidoManager.java:60)
02-19 02:31:24.792: E/AndroidRuntime(19447):    at com.psdmple.piano.Piano.onActivityResult(Piano.java:101)
02-19 02:31:24.792: E/AndroidRuntime(19447):    at android.app.Activity.dispatchActivityResult(Activity.java:4654)
02-19 02:31:24.792: E/AndroidRuntime(19447):    at android.app.ActivityThread.deliverResults(ActivityThread.java:2993)
02-19 02:31:24.792: E/AndroidRuntime(19447):    ... 11 more

我真的很感谢你的帮助=）

Answer 1

对象mediaPlayer永远不会使用构造函数启动，因此为null。

试图从SD卡播放音频

1 个答案: