Error checking in parameters reading

Hello:

I need to read some data as resting heart rate and heart rate zones. I do that as
rht = UserProfile.getProfile().restingHeartRate;
hrz = UserProfile.getHeartRateZones(UserProfile.getCurrentSport());


How can I check if the read was correct (it can fail for example because the used has not configured these fields in the device)? I can't find information in the docs. Can I perform the check via a null test such as?:
if(rht==null)
{
rht = some value;
}
if(hrz==null)
{
hrz = new[6];
}


Thanks