Voice Recording in Android

private static final String AUDIO_RECORDER_FILE_EXT_3GP = ".3gp";
private static final String AUDIO_RECORDER_FILE_EXT_MP4 = ".mp4";
private static final String AUDIO_RECORDER_FOLDER = "AudioRecorder";
private MediaRecorder recorder = null;
private int currentFormat = 0;
private int output_formats[] = { MediaRecorder.OutputFormat.MPEG_4, MediaRecorder.OutputFormat.THREE_GPP };
private String file_exts[] = { AUDIO_RECORDER_FILE_EXT_MP4, AUDIO_RECORDER_FILE_EXT_3GP };

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
setButtonHandlers();
enableButtons(false);
setFormatButtonCaption();
}

private void setButtonHandlers() {
((Button) findViewById(R.id.btnStart)).setOnClickListener(btnClick);
((Button) findViewById(R.id.btnStop)).setOnClickListener(btnClick);
((Button) findViewById(R.id.btnFormat)).setOnClickListener(btnClick);
}

private void enableButton(int id, boolean isEnable) {
((Button) findViewById(id)).setEnabled(isEnable);
}

private void enableButtons(boolean isRecording) {
enableButton(R.id.btnStart, !isRecording);
enableButton(R.id.btnFormat, !isRecording);
enableButton(R.id.btnStop, isRecording);
}

private void setFormatButtonCaption() {
((Button) findViewById(R.id.btnFormat)).setText(getString(R.string.audio_format) + " (" + file_exts[currentFormat] + ")");
}

private String getFilename() {
String filepath = Environment.getExternalStorageDirectory().getPath();
File file = new File(filepath, AUDIO_RECORDER_FOLDER);
if (!file.exists()) {
file.mkdirs();
}
return (file.getAbsolutePath() + "/" + System.currentTimeMillis() + file_exts[currentFormat]);
}

private void startRecording() {
recorder = new MediaRecorder();
recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
recorder.setOutputFormat(output_formats[currentFormat]);
recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
recorder.setOutputFile(getFilename());
recorder.setOnErrorListener(errorListener);
recorder.setOnInfoListener(infoListener);
try {
recorder.prepare();
recorder.start();
} catch (IllegalStateException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}

private void stopRecording() {
if (null != recorder) {
recorder.stop();
recorder.reset();
recorder.release();
recorder = null;
}
}

private void displayFormatDialog() {
AlertDialog.Builder builder = new AlertDialog.Builder(this);
String formats[] = { "MPEG 4", "3GPP" };
builder.setTitle(getString(R.string.choose_format_title)).setSingleChoiceItems(formats, currentFormat, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
currentFormat = which;
setFormatButtonCaption();
dialog.dismiss();
}
}).show();
}

private MediaRecorder.OnErrorListener errorListener = new MediaRecorder.OnErrorListener() {
@Override
public void onError(MediaRecorder mr, int what, int extra) {
Toast.makeText(AudioRecordingActivity.this, "Error: " + what + ", " + extra, Toast.LENGTH_SHORT).show();
}
};

private MediaRecorder.OnInfoListener infoListener = new MediaRecorder.OnInfoListener() {
@Override
public void onInfo(MediaRecorder mr, int what, int extra) {
Toast.makeText(AudioRecordingActivity.this, "Warning: " + what + ", " + extra, Toast.LENGTH_SHORT).show();
}
};