Question

I have android app with asynchrounous data sync from server via pressing button. However I need the button to be in all activities of app so I decided to have updateTask as standalone class.

In updateTask I download some xml data. Then use bussines object to process it and finaly let this bussines object to handle saving (or updating) to android db.

Based on ORMLite tutorials I should get databaseHelper by calling OpenHelperManager.getHelper(context, DatabaseHelper.class). My problem is that I need some context for OpenHelperManager which I currently don’t have.

I think that best way is pass activity’s context to updateTask but how do I do it? Also isn’t it weird to pass context further to bussines object which has nothing to do with any activity. And finally: what even is the context? Does it simply stand for activity parent or it has some deeper purpose?

Thanks 🙂

Answer 1

Here’s a couple ways of doing it. I’m pretty sure all 3 should work, but I haven’t tested them myself.

Method 1

Create a constructor for the AsyncTask that takes in the Context and store it so you can use it when it’s executing.

AsyncTask code

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

    private Context mContext;

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

    @Override
    protected Void doInBackground(Void... params) {
        DataBaseHelper helper = OpenHelperManager.getHelper(mContext, DatabaseHelper.class)
        // Your code here
    }
}

Implementation code (for an Activity)

new DataProcessor(this).execute();

Method 2

Pass the context in as an argument when you call the execute method

AsyncTask code

public class DataProcessor extends AsyncTask<Context, Void, Void>{

    @Override
    protected Void doInBackground(Context... params) {

        Context context = params[0];

        DataBaseHelper helper = OpenHelperManager.getHelper(context, DatabaseHelper.class)
        // Your code here
    }
}

Implementation code (for an Activity)

new DataProcessor().execute(this);

Method 3

Have a static instance of your context that the Async Task can access directly.
A way to do that can be found here: Static way to get 'Context' on Android?

AsyncTask code

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

    @Override
    protected Void doInBackground(Void... params) {

        DataBaseHelper helper = OpenHelperManager.getHelper(MyApplication.getAppContext(), DatabaseHelper.class)
        // Your code here
    }
}

Implementation code (for an Activity)

new DataProcessor().execute(this);