Building Error : Cannot find symbol

[strangerweather]

Hello, I'm looking for help with this error. I've googled it but still can't understand what to do.
Here it is:

frameworks/base/media/java/android/media/RingtoneManager.java:822: cannot find symbol
symbol  : variable MAX_NUM_RINGTONES
location: class android.provider.Settings.System
        if (!(subId >= 0 &&  subId < Settings.System.MAX_NUM_RINGTONES)) {
                                                    ^

I understand that at line 822 of RingtoneManager.java there is a variable called MAX_NUM_RINGTONES, and that this MAX_NUM_RINGTONES is not found in the file "android.provider.Settings.System". However, what do I need to do? Do I need to know how to code to sort this one out?

Thanks for any help, I would really appreciate it!