In this tutorial, I'll be making a UI with a start/stop recording button. I am using MediaRecording class to record the audio.

After making the layout, Call the method below on click of the mike button in the respective class:

MediaRecorder recorder;
boolean isRecording = false;

recordAudio()
{
if(isRecording==true)
            {
                isRecording = false;
                stopRecording();
                mike_btn.setText("Start recording");
            }
else
 {
                mike_btn.setText("Stop recording");
                recorder = new MediaRecorder();
                recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
                recorder.setOutputFormat(MediaRecorder.OutputFormat.AMR_NB);
                recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);

            File path = new File(Environment.getExternalStorageDirectory()
                    .getAbsolutePath(), "/files/");
            path.mkdirs();
            try
            {
                audioFile = File.createTempFile("TestSound", ".amr", path);
                recorder.setOutputFile(audioFile.getAbsolutePath());
                recorder.prepare();
            }
            catch (Exception e)
            {
                throw new RuntimeException(
                        "IOException on MediaRecorder.prepare", e);
            }
            recorder.start();
            isRecording = true;
 }
}

/**
     * This method stop audio recording and release resources
     */
    private void stopRecording()
    {
        isRecording = false;

        if (recorder != null)
    {
        recorder.stop();
        recorder.release();
        recorder = null;
    }
}

Also, add following permissions in the manifest file:

android:name="android.permission.RECORD_AUDIO"
android:name="android.permission.WRITE_EXTERNAL_STORAGE"

That's all and just simple to record an audio.

Hope you find this helpful :)