如何从 Android Activity 调用另一个 Activity AsyncTask 类获取 NPE

Question

1. ABC.class First activity Class.
2. XYZ.class is AsyncTask Activity Class.

having More than 10 Async task in my application ,So i kept Async task in Separate Class.

I am Calling the Another Activity Asynctask Class(XYZ.class) from a Activity(ABC.class).

Problem:

1.I Can call that Async Task from ABC.class but, I Kept Some Instance values inside OnCreate of XYZ.class Class(Getting Azure Local Database Data) . So Asynctask Getting NPE.

2.Oncreate Method is Not Running, When that Async task is calling From Other Activity.

3.Inside doinbackgroud iam getting NPE Error.

help me how to Solve this ,else Suggest me Any other Solution.

EDIT:1

In my Async task Iam fetching Data from Azure Server to Local DB ,so i need Instances what i kept inside Oncreate .

ABC.class

Calling the Async Task

 AsyncTaskload_UserGroupMappingTableClass myClass = new AsyncTaskload_UserGroupMappingTableClass(getApplicationContext());
                                                myClass.execute();

XYZ.class

th_tbusergroupmapping is my Database Name

 /*CLient for Table5 */
    private static MobileServiceClient mClient_UserGroupMapping;

    //ONLINE CLIENT  AZURE
    public  static MobileServiceTable<th_tbusergroupmapping> mToDoTable_UserGroupMapping_ServerAzure;

    //Offline CLient FOr  LOCAL Datbase.

    public static MobileServiceSyncTable<th_tbusergroupmapping> mToDoTable_UserGroupMapping_Local_Database;


     @Override
        protected void onCreate(Bundle savedInstanceState)
        {
            super.onCreate(savedInstanceState);
            try {
                // Create the Mobile Service Client instance, using the provided
    
                // Mobile Service URL and key
                mClient_UserGroupMapping = new MobileServiceClient(
                        "***********",
                        "**************",
                        this).withFilter(new ProgressFilter());
    
    
    /*UserGroupMapping*/
                // Get the Mobile Service Table instance to use
                mToDoTable_UserGroupMapping_ServerAzure = mClient_UserGroupMapping.getTable(th_tbusergroupmapping.class);
    
                // LOCAL DATABASE TABLE Instance to use
                mToDoTable_UserGroupMapping_Local_Database= mClient_UserGroupMapping.getSyncTable("th_tbusergroupmapping", th_tbusergroupmapping.class);
    
    
                //Init local storage
                initLocalStore().get();
    
    
            }
            catch (MalformedURLException e)
            {
    
                Log.i("Oncreate", "There was an error creating the Mobile Service. Verify the URL......!");
    
            } catch (Exception e) {
    
                Log.i("Oncreate", "Exception Occur......!");
            }
    
        }
    
    
     public static class AsyncTaskload_UserGroupMappingTableClass extends AsyncTask<Void, String, Void>
        {
    
            private Context context;
            public AsyncTaskload_UserGroupMappingTableClass(Context context) {
                this.context = context;
            }
    
            @Override
            protected void onPreExecute()
            {
                super.onPreExecute();
    
            }
            @Override
            protected Void doInBackground(Void... params)
            {
            }
     @Override
            protected void onPostExecute(Void result)
            {
    
                try
                {
    
                    Log.i("DONE ", "Data Sync Done Successfully UserGroupMapping 1");
    
    
                } catch (Exception e)
                {
                    e.printStackTrace();
    
                    Log.i("Exception ", "Post Excecute");
                }
            }
   
        }

Answer 1

Do not keep AsyncTask in an activity then; just keep it in an ordinary Java class and do not try to keep the data inside the instances of that class; store your information elsewhere: in a singleton class, or in sharedpreferences, or sqlite database, etc.