android – Passing parameters to Asynctask-ThrowExceptions

Exception or error:

I am using Async tasks to get string from the menu activity and load up some stuff..but i am
not able to do so..Am i using it in the right way and am i passing the parameters correctly?
Please see the code snippet. thanks

  private class Setup extends AsyncTask<Void, Integer, Void> {

    @Override
    protected Void doInBackground(Void... params) {
        try {
            if (!(getIntent().getExtras().isEmpty())) {
                Bundle gotid = getIntent().getExtras();
                identifier = gotid.getString("key");
            }
        } catch (Exception e) {
            e.getStackTrace();
        } finally {

            if (identifier.matches("abc")) {
                publishProgress(0);
                db.insert_fri();
            } else if ((identifier.matches("xyz"))) {
                publishProgress(1);
                db.insert_met();
            }
        }
        return null;
    }

    @Override
    protected void onProgressUpdate(Integer... i) {
        // start the song here
        if (i[0] == 0) {
            song.setLooping(true);
            song.start();
        }
    }

    @Override
    protected void onPostExecute(Void res) {

    }

    @Override
    protected void onPreExecute() {
        // do something before execution
    }
}
How to solve:

Avoid adding a constructor.

Simply pass your paramters in the task execute method

new BackgroundTask().execute(a, b, c); // can have any number of params

Now your background class should look like this

public class BackgroundTask extends AsyncTask<String, Integer, Long> {

    @Override
    protected Long doInBackground(String... arg0) {
        // TODO Auto-generated method stub
        String a = arg0[0];
        String b = arg0[1];
        String c = arg0[2];
        //Do the heavy task with a,b,c
        return null;
    }
    //you can keep other methods as well postExecute , preExecute, etc

}

###

Instead of this i would do

 private class Setup extends AsyncTask<String, Integer, Void> {

    @Override
    protected Void doInBackground(String... params) {
    String identifier = params[0];

          if (identifier.matches("abc")) {
                publishProgress(0);
                db.insert_fri();
            } else if ((identifier.matches("xyz"))) {
                publishProgress(1);
                db.insert_met();
            }
        }
        return null;
    }

    @Override
    protected void onProgressUpdate(Integer... i) {
        // start the song here
        if (i[0] == 0) {
            song.setLooping(true);
            song.start();
        }
    }

    @Override
    protected void onPostExecute(Void res) {

    }

    @Override
    protected void onPreExecute() {
        // do something before execution
    }
}

and check for “identifier” before invoking the asynctask to prevent overhead of creating a AsyncTask

like this

if (!(getIntent().getExtras().isEmpty())) {
                Bundle gotid = getIntent().getExtras();
                identifier = gotid.getString("key");
               new Setup().execute(identifier);
    }

###

A simple way is to add a constructor:

public Setup(String a, Int b) {
    this.a = a;
    this.b = b;
}

###

AsyncTask means doInBackground() returns Void, onProgressUpdate() takes Integer params and doInbackground takes… String params !

So you don’t need (and REALLY shouldn’t) use Intent, since it is meant to be used for passing arguments through Activities, not Threads.

And as told before, you can make a constructor and a global parameter to your class called “identifier”

public class Setup...
{
    private String identifier;

    public Setup(String a) {
    identifier = a;
    }
}

Hoped it could help.
Regards

Leave a Reply

Your email address will not be published. Required fields are marked *