Android user object parcelable issue
<p>I am developing simple travel agent android application. When application starts it loads list of cities, in the next activity user will see source and destination spinners, once user selects proper source and destination, it will take to third activity, it displays available travels if user selects one it takes to fourth activity in which user selects seat and continues to book ticket. In order to maintain complete user session I am maintaining a UserSession class, which is as follows (removing unnecessary logic in the code which is irrelevant to problems)</p>

<pre><code>    public class UserSession implements Parcelable {
        List&lt;City&gt; citiesList;
        HashMap&lt;String, City&gt; cityMap; // Map city name to code
        RouteSearchResult searchedRoutes;
        String sourceCity;
        String destinationCity;
        LocalStop selectedBoardingPoint;
        LocalStop selectedArrivalPoint;

        @Override
        public void writeToParcel(Parcel parcel, int flags) {
            try {
                parcel.writeList(citiesList);
                parcel.writeMap(cityMap);
                parcel.writeValue(searchedRoutes);
                parcel.writeString(sourceCity);
                parcel.writeString(destinationCity);
                parcel.writeValue(selectedBoardingPoint);
                parcel.writeValue(selectedArrivalPoint);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
    public class City implements Parcelable {
        String cityName;
        String cityId;
        @Override
        public void writeToParcel(Parcel parcel, int flags) {
            parcel.writeString(cityName);
            parcel.writeString(cityId);
        }
    }
    public class RouteSearchResult {
            City source;
            City destination;
            String date;
            List&lt;RouteDetails&gt; routeDetails;
    }
</code></pre>

<p>I have the following problems
1) I am getting run time exception while writing </p>

<pre><code>W/System.err(  817): java.lang.RuntimeException: Parcel: unable to marshal value com.travelagent.City@40605878
W/System.err(  817):    at android.os.Parcel.writeValue(Parcel.java:1132)
W/System.err(  817):    at android.os.Parcel.writeList(Parcel.java:519)
W/System.err(  817):    at com.travelagent.UserSession.writeToParcel(UserSession.java:201)
W/System.err(  817):    at android.os.Parcel.writeParcelable(Parcel.java:1151)
</code></pre>

<p>2) I commented <code>parcel.writeList(citiesList);</code> statement to see if I get any more problems, I got similar problem with <code>parcel.writeValue(searchedRoutes);</code></p>

<p>I have following questions, 
1) How to make a list of custom objects as parcelable?
2) Is it mandatory to make custom class like <code>City</code> also parcelable, which is part of actual class to be parceled. 
3) Is there any approach to solve this kind of problems like passing user session to all activities.</p>

<p>Please help, I searched, but I couldn't find  appropriate solution to make custom class parcelable. </p>
