Java Programming

I have a method that reads a value from a device and returns a double. The method is defined like this:

public class Device {
    // variables and stuff here.

    public double readValue() {
        double value = 0;
        try {
            // communicate with device here.
            // set value.
        } catch(Exception ex) {
            log.error(ex.getMessage());
            // tell parent I've failed somehow???
        }
        return value;
    }
}

...and is used like this (myDevice is an instance of the Device class):

double a = myDevice.readValue();

However I would really like to have a way of knowing if there has been an error. If my device has a read error how can I tell the parent class? I though of adding another parameter to the Device class like this:...

if (myDevice.errorStatus != 0) {
    // error!
}

...but obviously I can only call this after my readValue() has failed. Also, having readValue() return '0' to signify an error won't work, because zero may be a valid reading from the device. I cannot use a null value to signify an error either because I am not allowed to return a null double (compiler error). I feel that I'm going about this the wrong way. Can anyone please offer some advice? It's late and my brain is melting.

Many thanks,
MrQuan