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Question

ProgressDialog in AsyncTask throws an exception

Answer 1

+2 A:

ProgressDialog dialog;
@Override
    protected void onPreExecute() {
        dialog = new ProgressDialog(viewContacts.this);
        dialog.setMessage(getString(R.string.please_wait_while_loading));
        dialog.setIndeterminate(true);
        dialog.setCancelable(false);
        dialog.show();
    }

Pentium10 2010-06-25 21:32:04

This gives the exact same exception.

Computerish 2010-06-25 21:52:10

Then is something wrong with your Context. Change that from `this.getApplicationContext()` to just `this` when you pass it. Or if the AsyncTask is private to a Context class, just use the reference to the outer class as `MyClass.this`

Pentium10 2010-06-25 22:05:14

Using `this` instead of `this.getApplicationContext()` gets rid of the exception, but no dialog is displayed. (`pd.dismiss()` in `onPostExecute` also runs without error.)

Computerish 2010-06-26 02:39:00

@Computerish, Pentium10 meant, in your AsyncTask you need to use `YourActivity.this` instead of just `this`. In the `AsyncTask` `this` refers to the `AsyncTask` instance, while `YourActivity.this` refers to the activity that the `AsyncTask` was created in.

Qberticus 2010-06-26 04:20:35

@Computerish try looking into the samples in your SDK folder, and above my example, it simply works for an Activity that has no dialogs displayed

Pentium10 2010-06-26 08:24:45

Using `this` instead of `this.getApplicationContext()` has revealed another problem. When I call `ProgressDialog.show(...`, a ProgressDialog is displayed, but not until after the `AsyncTask` has completed. In other words, the data loads and then the dialog is displayed. If I include `pd.dismiss()` in my `onPostExecute()` then I never even see the dialog (presumable because it is closed before it ever gets opened).

Computerish 2010-06-26 22:41:15

Please post the whole code of your AsyncTask, and the method where you call execute(). Edit the original question.

Pentium10 2010-06-27 07:46:09

There you go! Thanks again for your help.

Computerish 2010-06-27 23:38:06

I don't see anything odd there, just that you call `fetcher.get()` right after you execute the task which runs in asynchronous way, so it will finish long after your code is executed.

Pentium10 2010-06-28 07:40:31

Could it be that the UI thread is busy waiting for the AsyncTask to finish, so it can't display the ProgressDialog? What should I do to prevent this?

Computerish 2010-06-28 14:38:52

I don't see that happening. Check the sample apps from your SDK samples folder.

Pentium10 2010-06-28 14:58:32

Ok, so I discovered that if I remove the `fetch.get()` line (the one that is hogging the UI thread), the ProgressDialog works, but now the results obviously aren't being displayed. How can I update an `ImageView` from my `AsyncTask`?

Computerish 2010-06-29 02:19:06

You can do some change in your interface in the `onProgressUpdate` method, or the `onPostExecute` both run on the UI thread. Whichever is suitable for you.

Pentium10 2010-06-30 07:56:20

... MyActivity.this worked for me.

mobibob 2010-09-30 11:55:01

Answer 2

A:

try this

  this.pd = ProgressDialog.show(this,"Loading...", "Please wait", true, false);

and yes I think the same the problem is with your context.

Jorgesys 2010-06-25 22:40:11

Using `this` instead of `this.getApplicationContext()` gets rid of the exception, but no dialog is displayed. (`pd.dismiss()` in `onPostExecute` also runs without error.)

Computerish 2010-06-26 02:39:31

Using `this` instead of `this.getApplicationContext()` has revealed another problem. When I call `ProgressDialog.show(...`, a ProgressDialog is displayed, but not until after the `AsyncTask` has completed. In other words, the data loads and then the dialog is displayed. If I include `pd.dismiss()` in my `onPostExecute()` then I never even see the dialog (presumable because it is closed before it ever gets opened).

Computerish 2010-06-26 22:38:11

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ProgressDialog in AsyncTask throws an exception

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