private static boolean equalsFloat(final Float f1, final Float f2, final float prec) {
        final boolean isF1Null = f1 == null;
        final boolean isF2Null = f2 == null;
        if (isF1Null != isF2Null) {
            return false;
        }
        if (isF1Null && isF2Null) {
            return true;
        }

        //if we come here, both are non-null
        return Math.abs(f1 - f2) < prec;
    }
Checks whether this instance contains changes relevant for saving the log
compared to a given previous instance
Note that this is NOT a hidden {@link #equals(Object)}-method!
main/src/main/java/cgeo/geocaching/log/OfflineLogEntry.java