How to use SQLite DB from AsyncTask?

Question

I've been using my Activity class to access my DB which made my program freeze sometimes.

So I decided to use AsyncTask instead to handle the DB.

My problem is I don't know how to instantiate my SQLite DB "TheDB" from AsyncTask's class

public class myClass extends AsyncTask<Void, Void, Void>{
private TheDB db;

any method() {
    this.db = new TheDB(this);  //<-- Error here
}

this worked fine on the Activity class, but it I dont know how to use it here

TheDB's constructor is TheDB(Context context) but this class is not a "context" so how can i use my DB here?

please provide examples if you can

and please do not give me links to google's references, am a newbie and i find them hard to follow

Manish Khot · Accepted Answer · 2010-11-24 02:51:46Z

9

you need to pass the application context here

this.db = new TheDB(getApplicationContext());

answered Nov 24, 2010 at 2:51

Manish Khot

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2 Comments

ZiGi Over a year ago

hi brotha, i tried but it says "The method getApplicationContext() is undefined for the type myClass", any suggestions!?!?

Manish Khot Over a year ago

You need to instantiate the Async task inside your activity as an inner Class.

a0s · Accepted Answer · 2011-07-11 20:40:11Z

6

import android.content.Context;

public class SuperTask extends AsyncTask<Void, Void, Void> {
    private final Context mContext; 

    public SuperTask(Context context) {
        super();
        this.mContext = context
    }

    protected Void doInBackground(Void... params) {
        // using this.mContext
    }
}

public class MainActivity extends Activity {
    // and run from Activity
    public void onButtonClick(View view) {
        new SuperTask(this.getApplicationContext()).execute(); 
    }
}

answered Jul 11, 2011 at 20:40

a0s

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Comments

lxknvlk · Accepted Answer · 2015-11-09 23:29:57Z

0

There are two ways that i see:

Pass a context object to your AsyncTask constructor, then instantiate database like this this.db = new TheDB(context);
Or you probably can pass the actual database object to the constructor, but the first approach seems better.

answered Nov 9, 2015 at 23:29

lxknvlk

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Comments

Cheryl Simon · Accepted Answer · 2010-11-24 02:27:29Z

-1

An important part of learning to program is learning to read and understand documentation. As documentation goes, the Android docs are pretty detailed, so its really worth your time to understand how they work.

As you can see in the AsyncTask docs, there is no onCreate or onExecute method in an AsyncTask.

The docs clearly walk you through the 4 main functions of an AsyncTask, onPreExecute(), doInBackground(Params...), onProgressUpdate(Progress...), onPostExecute(Result).

The likely choices for your instance are onPreExecute() or doInBackground(Params...). The difference is whether or not you want the initializition to occur on the UI thread. If you don't, then do it in doInBackground(Params...).

answered Nov 24, 2010 at 2:27

Cheryl Simon

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2 Comments

ZiGi Over a year ago

hi brotha, thanks for the quick reply, i did implement these automatically "using Eclipse IDE" but still wherever i use the line "this.db = new TheDB(this);" however, "this" is not a Context ans so cannot be used to instantiate the DB. so how to use the DB from this class? if there's a different way

Cheryl Simon Over a year ago

As khotmanship said, you can use an inner class within your Activity to get access to the activity's context.

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