How to show 'please wait' and avoid GUI hang ?

Question

I wrote application that contain 2 activities. In the first one - i need to give the user the option to choose image from the gallery and i send this image to some server. The Server return some result - and if the result is OK i need to show the second activity.

The problem that i have ..

1. when sending the image - i see that the screen is become black ... I want to avoid this and show some nice GUI of 'please wait' - how can i do it ?

2. i want to make this sending image to the server to be from other thread - how can i do it from android ? how to define new thread with callback that will be called when the thread is done ?

Thanks for any help.

Answer 1

Use an asynctask. It would go something like this:

public void sendImage() {
    SendToServer.execute();
}

protected class SendToServer extends AsyncTask<Void, Boolean, Void>
{    

    @Override
    protected void onPreExecute()
    {
        //display your dialog
    }

    @Override
    protected Boolean doInBackground(Void... arg0) {

        //code to send your image to the serve
    }

    @Override
    protected void onPostExecute (Boolean updateSuccess)
    {     
        //close your dialog
        //If image was successfully sent open your other activity
    }
}

Answer 2

For question number 1:

You should use a ProgressDialog or a ProgressBar in order to show to the user that an operation is being executed. For more information you can check here: http://developer.android.com/reference/android/app/ProgressDialog.html

For question number 2: A good solution would be to use AsyncTask for this operation which gives you a set of callback functions to control the operation. For more information you can check here: http://developer.android.com/reference/android/os/AsyncTask.html

Hope this helps for now!

Answer 3

1. you can define your custom layout and use the Activity.setContentView method to put whatever you want in your GUI. For instance you can put a ProgressBar widget.

2. As you have noticed, you wrote your android app in Java SE. Thread are fully supported.

Answer 4

This question has an answer which addresses the problem. Use that answer as a start, and let us know if you have any problems with some specific part.

Download image for imageview on Android

Good luck