ANR While calling a method of adapter class

Question

I am trying to retrieve the row_count of a table from SQLite. The code, which I used to do this task is freezing my application. This is entirely run on back-end, nothing is there in the MainUI thread. But, also I am getting ANR error.

This is my code, where I am calling the method -

public class del_person extends Activity{
String[] images = {}; 

 @Override 
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.del_person);
        final adapter info = new adapter(this);

   //     new del_person_Dup(null).execute();

        new Task(info).execute((Void)null);
 }
}



class Task extends AsyncTask<Void, Void, Void> {
String[] images = {}; 
adapter mAdapter; 

Task(adapter adapter)  {
   mAdapter = adapter;
}

@Override
protected Void doInBackground(Void... params) {
  // the code from the Runnable using the mAdapter instead of info.


    Log.v("distinctrowcount() is:",""+mAdapter.distinctrowcount()+"");
    Log.v("started del_person.java","started del_person.java");

    for (int i=0;i<mAdapter.distinctrowcount();i++)

{
        Log.v ("This is the "+i+"th iteration","This is the "+i+"th iteration");
    images[i] =mAdapter.getPersonList(i+1); 
    Log.v("Persons",images[i]);
}

return null;
}
}

I also tried using AsyncTask for this. But also, I am unable to come out of this.

Here is my distinctrowcount() from adapter class:

adapter.java:

public int distinctrowcount()
{
    int rc = 0;
    try {
        open();
        rc = mDbHelper.getdistinctrc();
        close();
    }
    catch (Exception e)
    {
        e.printStackTrace();
    }
    return rc;
}

helper.java - getdistinctrc():

public int getdistinctrc() {

        // TODO Auto-generated method stub

        SQLiteDatabase myDB;            
        int values = 0;
        int distinct_count = 0;
         try {
              myDB=this.openDataBase();                   
              Cursor c=myDB.rawQuery("select count (DISTINCT FileName) from Photos;",null);
              if (c != null ) {

                          String h = "";
                          while(c.moveToFirst()){
                              distinct_count = c.getInt(0);
                             //   h = c.getString(c.getColumnIndex("COUNT(*)"));
                            }

                     } 


                  if(c != null)
                 {
                         c.close();
                     myDB.close();

                  }                    
                  }catch(SQLException sqle){

                  throw sqle;

                  }
         return distinct_count;  
    }

AsyncTask code:

class Task extends AsyncTask<Void, Void, Void> {
    String[] images = {}; 
    adapter mAdapter; 

    Task(adapter adapter)  {
       mAdapter = adapter;
    }

    @Override
    protected Void doInBackground(Void... params) {
      // the code from the Runnable using the mAdapter instead of info.


        Log.v("distinctrowcount() is:",""+mAdapter.distinctrowcount()+"");
        Log.v("started del_person.java","started del_person.java");

        for (int i=0;i<mAdapter.distinctrowcount();i++)

    {
            Log.v ("This is the "+i+"th iteration","This is the "+i+"th iteration");
        images[i] =mAdapter.getPersonList(i+1); 
        Log.v("Persons",images[i]);
    }

    return null;
}
}

Is there any other better way to implement this, other than Runnable() and AsyncTask? Please help me with some sample code.

Thanks in advance.

Answer 1

Your current code doesn't run those database queries on a background thread. Use an AsyncTask instead like this:

static class Task extends AsyncTask<Void, Void, Void> {

    adapter mAdapter; 

    Task(adapter adapter)  {
       mAdapter = adapter;
    }

    @Override
    protected Void doInBackground(Void... params) {
      // the code from the Runnable using the mAdapter instead of info.
    return null;
}

And in the Activity's onCreate() you'll use something like:

new Task(info).execute((Void)null);