[json-lib-user] Converting GregorianCalendar object, Java to JSON and back

[Darlene W. <dar...@gm...>]

Hi, I'm new to json-lib.  I want to convert a Java class into JSONObject and
then back again.  I am able to do this conversion with a Date class.
However, the class I want to convert contains a nested XMLGregorianCalendar
object, which has issues when converting from JSONObject to Java.

I've tried to create a simple test case that converts only a
GregorianCalendar object (
http://java.sun.com/javase/6/docs/api/java/util/GregorianCalendar.html).
This works fine when converting from Java to JSONObject, but the reverse
conversion gives an InstantiationException error when calling toJava().
Here is my sample code:


            GregorianCalendar gc = DateUtil.getCalendar(-7);
            System.out.println(gc.toString());

            // Convert object to JSON
            JSONObject jsonObject = (JSONObject) JSONSerializer.toJSON(gc);
            System.out.println(jsonObject.toString());


            // Convert JSON object back into Java object
            GregorianCalendar gc2;
            JsonConfig jsonConfig = new JsonConfig();
            jsonConfig.setRootClass(GregorianCalendar.class);
            gc2 = (GregorianCalendar) JSONSerializer.toJava(jsonObject,
jsonConfig);
            System.out.println(gc2.toString());


The output is as follows:
java.util.GregorianCalendar[time=1212788878236,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=java.util.SimpleTimeZone[id=GMT-07:00,offset=-25200000,dstSavings=3600000,useDaylight=true,startYear=0,startMode=3,startMonth=3,startDay=1,startDayOfWeek=1,startTime=7200000,startTimeMode=0,endMode=2,endMonth=9,endDay=-1,endDayOfWeek=1,endTime=7200000,endTimeMode=0],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2008,MONTH=5,WEEK_OF_YEAR=23,WEEK_OF_MONTH=1,DAY_OF_MONTH=6,DAY_OF_YEAR=158,DAY_OF_WEEK=6,DAY_OF_WEEK_IN_MONTH=1,AM_PM=1,HOUR=3,HOUR_OF_DAY=15,MINUTE=47,SECOND=58,MILLISECOND=236,ZONE_OFFSET=-25200000,DST_OFFSET=3600000]
{"firstDayOfWeek":1,"gregorianChange":{"date":4,"day":4,"hours":16,"minutes":0,"month":9,"seconds":0,"time":-12219292800000,"timezoneOffset":480,"year":-318},"lenient":true,"minimalDaysInFirstWeek":1,"time":{"date":6,"day":5,"hours":14,"minutes":47,"month":5,"seconds":58,"time":1212788878236,"timezoneOffset":420,"year":108},"timeInMillis":1212788878236,"timeZone":{"DSTSavings":3600000,"ID":"GMT-07:00","displayName":"GMT-07:00","rawOffset":-25200000}}
net.sf.json.JSONException: java.lang.InstantiationException
    at net.sf.json.JSONObject.toBean(JSONObject.java:304)
    at net.sf.json.JSONObject.toBean(JSONObject.java:420)
    at net.sf.json.JSONSerializer.toJava(JSONSerializer.java:69)

...

Like I said, I am able to get the same code to work on other objects, such
as Date objects, so what am I missing?  Is there a limitation on the types
of objects that can be converted to JSONObject and back?

Any help or pointers is greatly appreciated!

Darlene