my application not read if statement in postexecute method

Question

my code will crash if i not comment statement else if (message.equals("holiday")) on postexecute tell me why is not go further if not euqal this line (message.equals("holiday")) why not print "School is off today. Reason: if i comment else if (message.equals("holiday")) this code app work fine check my if else stateement please

          String message;

        public class getDataTask extends AsyncTask<Void, Void, Void> {

    getDataTask() {

    }

    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub
         yourBoolean=false;
    }

    @Override
    protected Void doInBackground(Void... arg0) {
        // TODO Auto-generated method stub

        displayData();
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        // TODO Auto-generated method stub
        yourBoolean=true ;

        if ((Category_ID.size() > 0) ) {



                            listCategory.setAdapter(cla);
                            cla.notifyDataSetChanged() ;
                            listCategory.invalidateViews();
                            menu_nametxt.setText(mVal2);

                        }





else if (message.equals("holiday")) 
{
    menu_nametxt.setText("No menu available .");
    listCategory.setVisibility(View.GONE);
}   
        else
        menu_nametxt.setText("School is off today. Reason: "+mVal3);
    listCategory.setVisibility(View.GONE);

             }


                   private void displayData() {



        Cursor mCursor3 =  db.selectQuery("SELECT * FROM uss_vacation WHERE calendar_id);


    if (mCursor3.moveToFirst()) {
        do {


       Vacation_Date.add(mCursor3.getString(mCursor3.getColumnIndex("date")));

      if(mCursor3.getString(mCursor3.getColumnIndex("date")).equals(mydate))
    {
    message = "holiday";
           String  mVal  ;
    mVal = (mCursor3.getString(mCursor3.getColumnIndex("title")));

    mVal2 = mVal.toString();


    mCursor3.close();
    return;

    }


        } while (mCursor3.moveToNext());
    }

          mCursor3.close();
             }




              if i comment this code application print "School is off today. Reason: text


            else if (message.equals("holiday")) 
 // {
 //     menu_nametxt.setText("No menu available .");
 //     listCategory.setVisibility(View.GONE);
 // }

problem is on if else statement if i coment this else if block else if (message.equals("holiday")) code work fine if i uncoment this coce block else if (message.equals("holiday")) app crash tell me why if conditionnot satisfy its not goes last else statement?? — user2947238, Nov 02 '13 at 10:17
One of the possibility is because the `message` is `null`, hence the app throwing `NullPointerException` and crashing the app. Check whether the `message` has value or not. — Andrew T., Nov 02 '13 at 10:18
what is your message variable? where it is initialize? is that contain data or it is null? — Hardik, Nov 02 '13 at 10:19
is your result is your message ? than it should be message=result; — Hardik, Nov 02 '13 at 10:21
no on first time when app start else if (message.equals("holiday")) this statement is false — user2947238, Nov 02 '13 at 10:22
message is null on initialize its only true when thisline satisfy if(mCursor3.getString(mCursor3.getColumnIndex("date")).equals(mydate)) { message = "holiday"; — user2947238, Nov 02 '13 at 10:24
when app reach this statement else if (message.equals("holiday")) message have no value its null — user2947238, Nov 02 '13 at 10:26

score 0 · Answer 1 · edited May 23 '17 at 12:13

Since message is null when the app is run for the first time, when the if-else statement reaches else if (message.equals("holiday"), it will throws NullPointerException instead of false and crashing the app.

see SO: Java null String equals result

Consider initialize the message with empty string instead. (i.e. message = "";).

OR

Change the order of checking to else if ("holiday".equals(message)).

my application not read if statement in postexecute method

1 Answers1