Question

In webservice class, it will retrieve database from online and put into list:

public List<List_NewsComment> allCommentList;
public void GetCommentNews( final int gCommentNewsID)
{
    Thread networkThread=new Thread(){
        @Override
        public void run(){

            try
            {
                SoapObject request= new SoapObject(NAMESPACE,get_Comment_METHOD_NAME);
                SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11);
                HttpTransportSE androidHttpTransportSE= new HttpTransportSE(URL,60000);

                request.addProperty("itemid", gCommentNewsID);
                envelope.setOutputSoapObject(request);
                androidHttpTransportSE.call(get_Comment_SOAP_ACTION, envelope);

                SoapObject result=(SoapObject)envelope.bodyIn;
                RetrieveFromSoap( result);
            }
            catch(Exception ex)
            {
                ex.printStackTrace();
            }
        }

    };
    networkThread.start();

}

public List<List_NewsComment> RetrieveFromSoap(SoapObject soap)
{
    allCommentList= new ArrayList<List_NewsComment>();
    Vector<Object> property2 = extracted(soap);

    for (int i = 0; i< property2.size();i++){

        SoapObject getPropertyD=(SoapObject)property2.get(i);


        List_NewsComment addcomment= new List_NewsComment();
        addcomment.setcommentDate(getPropertyD.getProperty("date").toString());
        addcomment.setUserName( getPropertyD.getProperty("name").toString());
        addcomment.setCommentContent(getPropertyD.getProperty("comment").toString());

        allCommentList.add(addcomment);
    }
    webservice.allCommentList.size();        <-- can call here no problem
    return allCommentList;
}

private static Vector<Object> extracted(SoapObject soap) {
    return (Vector<Object>)soap.getProperty(0);
}

In Main Activity class, i want to check the size of list:

Database_WebService webservice = new Database_WebService(this);
    webservice.GetCommentNews(newsid);
webservice.allCommentList.size();            <-- cannot call here, what is the problem

It returns me nullpointerexception.

What is the problem????

Answer 1

Make your List static so you can access it anywhere using that class name .

Like

public static List<List_NewsComment> allCommentList;
Database_WebService.allCommentList.size();

Or

As everyone suggest make one function in your class and return the size of array in that function. Please see code below.

public int getCommentListSize()
{
    return allCommentList.size(); 
}

then call this method as

Database_WebService databaseWebservice = new Database_WebService(this);   
int size =databaseWebservice.getCommentListSize.size();