Android - getAltitude only return integer numbers

I've implemented an app that uses GPS, with google API. As far as I read the documentation, the Location.getAltitude returns a double, but all the values I got are round integer numbers.

I wanted the value with at least 1 decimal place.

Am I doing something wrong, or is it expected to behave like that?

Here's relevant parts of my code:

protected void createLocationRequest() {
    mLocationRequest = new LocationRequest();
    mLocationRequest.setInterval(UPDATE_INTERVAL);
    mLocationRequest.setFastestInterval(FASTEST_INTERVAL);
    mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    mLocationRequest.setSmallestDisplacement(DISPLACEMENT);
}

@Override
public void onLocationChanged(Location locationRead) {

//a lot of stuff, check signal, filter wrong reading, etc...

currentLocation = locationRead;

//compare last location with current location, some calculation, etc...

//already used String.format("%.1f",currentLocation.getLongitude()).replace(",", "."),
DecimalFormat df = new DecimalFormat("#.0");

//Send information to another class
GPS.this.interfaceGPS_Activity.locationChanged(
                (currentLocation.distanceTo(lastLocation) / 1000),
                (timeSplit),
                formatter.format(dateTimeOfGPS),
                String.format("%.7f", currentLocation.getLatitude()).replace(",", "."),
                String.format("%.7f", currentLocation.getLongitude()).replace(",", "."),
                df.format(currentLocation.getAltitude()).replace(",","."),
                currentPaceForLabel
        );

The altitude sent is always xyz.0, like 920.0 921.0 1011.0, it's never 920.6 or 921.2 always .0

You aren't doing anything wrong, it just isn't that accurate. GPS doesn't even give you 1m of accuracy, much less tenth of a meter.