How to run queries in the background

I have listed of products with different category. I have to sort them. Because of the queries, It is taking more time to load. Between two activities, the screen is coming black. I want to run the query in the background. How can I do that and how to use its result in main activity? private class InsertTask extends AsyncTask { String cat;

@Override
protected void onPreExecute() {
    super.onPreExecute();
}

@Override
protected Boolean doInBackground(String... params) {

 Boolean success = false;

    try {

  开发者_运维百科      category(cat);
        success = true;
    } catch (Exception e) {
        if(e.getMessage()!=null)
            e.printStackTrace();
    }
    return success;
}



@Override
protected void onPostExecute(Boolean success) {
    super.onPostExecute(success);
}
private void category(String category) {

    try{
        Cursor1 = mDbHelper.fetchcategory(category);

          }catch(Exception e){
            Log.v("Excep", ""+e);
          }
    }

And when called

    InsertTask task = new InsertTask();
    task.execute();

I have listed the category in buttons. How can I get the values then?

You should use AsyncTask for that. And some more info.

Its good you have thought of AsyncTask. Firstly, you can declare this class as inner in you class activity (if you haven't previously did) and so you are able to access you view class members.

You can do this also by creating thread and one handler that will be used to update your UI components. Remember that if you use threads you'll need to lock/unlock your database object because of the thread safety(if any other thread is accessing the database for any reason). Read more about thread safety of dbs.

I was doing some searching myself, and I came across this read, its rather long but looks extremely helpful, with lots of code examples. (I bookmarked it for myself).

Threads, Async, and Handlers O MY!

But some form of threading is the ticket.

From Android dev. (My favorite code snippet)

public void onClick(View v) { 
new Thread(new Runnable() {   
public void run() {      
//Do Work here 
           }  
    }).start();
}