android - Java complex object to JSON with GSON -

i need make list of (sub)lists of objects (some mybook) , save android internal storage. , each sublist has name.

mybook:

public class mybook implements parcelable{  string name; list<string> authors; string publisher; bitmap preview; string description; list<string> isbn; list<string> isbntype; //string isbn; string imglink=""; string googlelink =""; string publisheddate; 

listofmybook (sublists):

public class listofmybook extends arraylist<mybook>{     public string listname;      @override     public string tostring() {         // todo auto-generated method stub         return listname;     }  } 

my current code serialization , deserialization:

public static final string my_list_file = "mylist.json"; public static void exporttoxml(context context, list<listofmybook> listlistbook){     gson gson = new gson();     string json = gson.tojson(listlistbook);     log.d("gson",json);     fileoutputstream outputstream;      try {       outputstream = context.openfileoutput(my_list_file, context.mode_private);       outputstream.write(json.getbytes());       outputstream.close();     } catch (exception e) {         log.d("exporttoxml",e.tostring());       e.printstacktrace();     } }   public static list<listofmybook> importfromxml(context context){     fileinputstream fis = null;     try {         fis = context.openfileinput(my_list_file);     } catch (filenotfoundexception e) {         // todo auto-generated catch block         e.printstacktrace();     }      inputstreamreader isr = new inputstreamreader(fis);      bufferedreader bufferedreader = new bufferedreader(isr);      stringbuilder sb = new stringbuilder();      string line;      try {         while ((line = bufferedreader.readline()) != null) {              sb.append(line);          }     } catch (ioexception e) {         // todo auto-generated catch block         e.printstacktrace();     }      string json = sb.tostring();      type listtype = new typetoken<list<listofmybook>>() {}.gettype();     gson gson = new gson();     return gson.fromjson(json, listtype); } 

this not save name of listofmybook , not save empty listofmybook. better implementation? classes can modified.

so have came own solution not extend arraylist<mybook> create new class this:

public class listofmybook implements parcelable{     public string listname;     public list<mybook> listofbook = new arraylist<mybook>(); }