Maxwell 10 API documentation

public void onResume() {
    IntentFilter intentFilter = new IntentFilter(Intent.ACTION_HEADSET_PLUG);
    registerReceiver(mMyHeadsetObserver, intentFilter);
    super.onResume();
}

public void onDestroy() {
    unregisterReceiver(mMyHeadsetObserver);
    super.onDestroy();
}

private class MyHeadsetObserver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        if (intent.getAction().equals(Intent.ACTION_HEADSET_PLUG)) {
            int state = intent.getIntExtra("state", -1);
            switch (state) {
                case 0:
                    mTextView.setText("Handset / Headset: Disconnected");
                    break;
                case 1:
                    mTextView.setText("Handset / Headset: Connected");
                    break;
            }
        }
    }
}

In AndroidManifest.xml
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />