CODEWITHSUNDEEP
androidandroid-asynctasknullandroid-volley
firstofthebadones
firstofthebadones

Reputation: 37

Android AsyncTask null value parameter

i've a little problem with my code. I'm trying to perform a volley request on doInBackground behaviour and then to use its result to set some layout elements. Here's the async snippet:

private class MyAsyncTask extends AsyncTask<String, Void, Message>

{
    @Override
    protected Message doInBackground(String... params) {
        rm = new RequestManager(MessageDisplay.this);
        idM = params[0];
        retrieveMessage(new VolleyCallbackOp(){
            public void onSuccess(List<Message> ml) {
                m = ml.get(0);
                Log.d("print1", m.getContent());   <---- this is fine
            }
        });
        Log.d("print2", m.getContent());   <---- m always null
        return m;
    }
    @Override
    protected void onPostExecute(Message m) {
        super.onPostExecute(m);
        Log.d("messaggio", m.getContent());
        mds = new MessageDisplaySetter(MessageDisplay.this);
        View v = mds.setMessageDisplayInfo(m, 3);
        contentD.addView(v);

                }
            }
        }); 
    }

this code is called in activity onCreate():

Message m = new Message();
String target2 = i.getExtras().getString("messageId");
            new MyAsyncTask().execute(target2);

The problem is that the Log "print2" tell the variable m is null while "print1" is ok. Have you any tip to pass the result of this request to the related onPostExecute()?

Upvotes: 0

Views: 198

Answers (1)

Murat Karag&#246;z
Murat Karag&#246;z

Reputation: 37594

The reason why your log for print2 is null - is because you are in a race condition. By calling new VolleyCallbackOp you are doing an asynchrounous network call which might take a while to complete. Your code does not wait until it's finished. That's why print2 is null most of the time.

There are several solutions for your case. One of them is to use the callback mechanism of onSuccess and do your logic there.

Upvotes: 2

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