java.lang.RuntimeException: setAudioSource failed Google Guide Code is throwing error

This is my code and actually Google Developer Android Guide's code. But this code throwing error "java.lang.RuntimeException: setAudioSource failed.". I tried all the solutions and it still gives error.

private static final String LOG_TAG = "AudioRecordTest";
private static String mFileName = null;

private RecordButton mRecordButton = null;
private MediaRecorder mRecorder = null;

private PlayButton   mPlayButton = null;
private MediaPlayer   mPlayer = null;

private void onRecord(boolean start) {
    if (start) {
        startRecording();
    } else {
        stopRecording();
    }
}

private void onPlay(boolean start) {
    if (start) {
        startPlaying();
    } else {
        stopPlaying();
    }
}

private void startPlaying() {
    mPlayer = new MediaPlayer();
    try {
        mPlayer.setDataSource(mFileName);
        mPlayer.prepare();
        mPlayer.start();
    } catch (IOException e) {
        Log.e(LOG_TAG, "prepare() failed");
    }
}

private void stopPlaying() {
    mPlayer.release();
    mPlayer = null;
}

private void startRecording() {
    mRecorder = new MediaRecorder();
    mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);  // This row is throwing error. 
    mRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
    mRecorder.setOutputFile(mFileName);
    mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);

    try {
        mRecorder.prepare();
    } catch (IOException e) {
        Log.e(LOG_TAG, "prepare() failed");
    }

    mRecorder.start();
}

private void stopRecording() {
    mRecorder.stop();
    mRecorder.release();
    mRecorder = null;
}

class RecordButton extends Button {
    boolean mStartRecording = true;

    OnClickListener clicker = new OnClickListener() {
        public void onClick(View v) {
            onRecord(mStartRecording);
            if (mStartRecording) {
                setText("Stop recording");
            } else {
                setText("Start recording");
            }
            mStartRecording = !mStartRecording;
        }
    };

    public RecordButton(Context ctx) {
        super(ctx);
        setText("Start recording");
        setOnClickListener(clicker);
    }
}

class PlayButton extends Button {
    boolean mStartPlaying = true;

    OnClickListener clicker = new View.OnClickListener() {
        public void onClick(View v) {
            onPlay(mStartPlaying);
            if (mStartPlaying) {
                setText("Stop playing");
            } else {
                setText("Start playing");
            }
            mStartPlaying = !mStartPlaying;
        }
    };

    public PlayButton(Context ctx) {
        super(ctx);
        setText("Start playing");
        setOnClickListener(clicker);
    }
}

public MainActivity() {
    mFileName = Environment.getExternalStorageDirectory().getAbsolutePath();
    mFileName += "/audiorecordtest.mp4";
}

@Override
public void onCreate(Bundle icicle) {
    super.onCreate(icicle);

    LinearLayout ll = new LinearLayout(this);
    mRecordButton = new RecordButton(this);
    ll.addView(mRecordButton,
            new LinearLayout.LayoutParams(
                    ViewGroup.LayoutParams.WRAP_CONTENT,
                    ViewGroup.LayoutParams.WRAP_CONTENT,
                    0));
    mPlayButton = new PlayButton(this);
    ll.addView(mPlayButton,
            new LinearLayout.LayoutParams(
                    ViewGroup.LayoutParams.WRAP_CONTENT,
                    ViewGroup.LayoutParams.WRAP_CONTENT,
                    0));
    setContentView(ll);
}

@Override
public void onPause() {
    super.onPause();
    if (mRecorder != null) {
        mRecorder.release();
        mRecorder = null;
    }

    if (mPlayer != null) {
        mPlayer.release();
        mPlayer = null;
    }
}

}

This is my Android Manifest

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
<uses-permission android:name="android.permission.RECORD_AUDIO"></uses-permission>

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

Pls help. I'm trying solve the problem for three days.

I solved this problem. Use of Android Permissions is changed after the Android 6.0 . I added this method my cod:

private boolean Permissions(){
        int permissionWRITE_EXTERNAL_STORAGE = ContextCompat.checkSelfPermission(this, android.Manifest.permission.WRITE_EXTERNAL_STORAGE);
        int permissionRECORD = ContextCompat.checkSelfPermission(this, Manifest.permission.RECORD_AUDIO);
        List<String> listPermissionsNeeded = new ArrayList<>();

        if (permissionWRITE_EXTERNAL_STORAGE != PackageManager.PERMISSION_GRANTED) {
            listPermissionsNeeded.add(android.Manifest.permission.WRITE_EXTERNAL_STORAGE);
        }
        if (permissionRECORD != PackageManager.PERMISSION_GRANTED) {
            listPermissionsNeeded.add(android.Manifest.permission.RECORD_AUDIO);
        }

        if (!listPermissionsNeeded.isEmpty()) {
            ActivityCompat.requestPermissions(this, listPermissionsNeeded.toArray(new String[listPermissionsNeeded.size()]), REQUEST_ID_MULTIPLE_PERMISSIONS);
            return false;
        }

        return  true;


    }

And ı use this method in my onCreate method.

if (!Permissions()) {
            return;
        }