Error creating Media Player; Java, Android Studio

Question

Well i know, that there are 2 results of MediaPlayer.create() function: created stream or null, and in this case i get the second one result. Got some thoughts about file path, but still don't know where i'm wrong. (Trying to play a random track from assets folder). Thanks in advance!

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Button play36 = (Button)findViewById(R.id.threesix);


    String[] listOfFiles = new String[0];
    try {
        listOfFiles = getAssets().list("");
    } catch (IOException e) {
        e.printStackTrace();
    }

        int itemIndex = (int) (Math.random() * listOfFiles.length);
        String file = listOfFiles[itemIndex];
        String filePath = "file:///android_asset/".concat(file);
        Uri uri = Uri.parse(filePath);
        final MediaPlayer mediaPlayer = MediaPlayer.create(MainActivity.this, uri);

        play36.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mediaPlayer.start();
            }
        });

}

Answer 1

I tried your code and i too got that exception i have modified the code. You can try it. It is working on my device

                    String[] listOfFiles = new String[0];
                    try {
                        listOfFiles = getAssets().list("");
                        //  int itemIndex = (int) (Math.random() * listOfFiles.length);
                        int itemIndex = 1;
                        String file = listOfFiles[itemIndex];
                        AssetFileDescriptor afd = null;
                        afd = getAssets().openFd(file);

                        MediaPlayer mediaPlayer = new MediaPlayer();
                        mediaPlayer.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(), afd.getLength());

                        mediaPlayer.prepare();
                        mediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
                            @Override
                            public void onPrepared(MediaPlayer mediaPlayer) {
                                mediaPlayer.start();
                            }
                        });

                    } catch (IOException e) {
                        e.printStackTrace();
                    }

NOTE: I have commented the random itemIndex because assets folder contain other things too. Like i had these in my folder so mind this thing.

For this you can limit the random number generation to number of your audio files in assets folder.