Using CellSignalStrengthGsm only gives Integer.MAX_VALUE

after seeing that question and the answers (thanks by the way) I wrote this code wich is pretty much the same as in the answers:

try {
        List<CellInfo> cellInfoList = telephonyManager.getAllCellInfo();
        for (CellInfo cellInfo : cellInfoList) {
            if (cellInfo instanceof CellInfoGsm) {
                CellInfoGsm cellInfoGsm = (CellInfoGsm) cellInfo;
                CellIdentityGsm cellIdentity = cellInfoGsm.getCellIdentity();
                final CellSignalStrengthGsm gsm = ((CellInfoGsm) cellInfo).getCellSignalStrength();
                rsrpValue = gsm.getDbm();
                pciValue = cellIdentity.getCid();
            } else if (cellInfo instanceof CellInfoCdma) {
                CellInfoCdma cellInfoCdma = (CellInfoCdma) cellInfo;
                CellIdentityCdma cellIdentity = cellInfoCdma.getCellIdentity();
                pciValue = cellIdentity.getBasestationId();
            } else if (cellInfo instanceof CellInfoLte){
                    CellInfoLte cellInfoLte = (CellInfoLte) cellInfo;
                    CellIdentityLte cellIdentity = cellInfoLte.getCellIdentity();
                    pciValue = cellIdentity.getPci();
            } else {
                throw new Exception("Unknown type of cell signal!");
            }
        }
    } catch (Exception e) {
        Log.e(TAG, "Unable to obtain cell signal information", e);
    }

But when I display rsrpValue or pciValue for GSM, I always get the maximum integer value (2147483647). I tried this on a phone with the API 17. Is there something wrong in my code?

Thanks

Solution

Try to use the good old PhoneStateListener to listen for signal strength changes. Here is what worked for me. Use this to register the listener:

private TelephonyManager telManager = (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);
int currentSignalStrength = 0;
int asu = 0;

telManager.listen(new SignalStrengthListener(), PhoneStateListener.LISTEN_SIGNAL_STRENGTHS);

And this is the actual listener:

private class SignalStrengthListener extends PhoneStateListener{

    @Override
    public void onSignalStrengthsChanged(SignalStrength signalStrength)
        {
            super.onSignalStrengthsChanged(signalStrength);
            if (telManager.getPhoneType()== TelephonyManager.PHONE_TYPE_CDMA)
                currentSignalStrength = signalStrength.getCdmaDbm();                  
            else
                asu = signalStrength.getGsmSignalStrength();
        }
    }

Tested on Xperia Z which has the same problems using CellInfoGsm.