How to handle feedback from background threads if the user uses the back button?

Posted by Janusz on Stack Overflow See other posts from Stack Overflow or by Janusz
Published on 2010-03-31T11:11:31Z Indexed on 2010/03/31 11:13 UTC
Read the original article Hit count: 195

Filed under:

android

|

threading

|

back-button

I have the following problem:

I have an Activity where a user can start a web search showing a new activity to show a progress bar until the results are shown. Now the user can either wait for the results or maybe think about the search parameters, hit the back button and triggering a new search. The search is running in an Async Task and therefor still running if the user hits back. At the moment the thread finishes it calls some methods on the old activity causing the activity to show a dialog.

This causes the system to crash because the dialog tries to show itself with a reference to an activity that is not longer present on the screen.

How can I achieve a dialog that is only shown if the activity is still active?

© Stack Overflow or respective owner

Related posts about android

Please verify my layout: bottom button keeps coming up over keyboard

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi everyone, I have a layout which does almost what I want. There's just one bug regarding the button at the bottom. I should stay at the bottom at all times. But whenever I bring up the soft-keyboard the button will be displayed above the keyboard. This is not what I want but it should become covered… >>> More
Android programming. Application stopped unexpectedly.

as seen on Stack Overflow - Search for 'Stack Overflow'
I've just created a prototype of interface for my android app and tried to run it. Unfortunately I get an error that my app has stopped unexpectedly (my reputation doesn't allow me to post images so follow my links): screenshot of error message This is layout mode of editing. Everything looks as… >>> More
Listview Row Overlap Problem

as seen on Stack Overflow - Search for 'Stack Overflow'
I just updated my app and I am getting some odd complaints from people who update it. I am only getting complaints from people with non-stock android phones (phones that manufacturers have modified...HTC phones, cliq, pulse, etc), other phones like the Droid, Nexus work fine. My app (Photo Frame Deluxe)… >>> More
Why are some of my view not aligned correctly at the bottom of my relative layout?

as seen on Stack Overflow - Search for 'Stack Overflow'
I have problems getting some of my views aligned in a relative layout that I use inside a row of my listview. Here is a screenshot from the layout builder in Eclipse, this is what I think it should look like: The next image is from the emulator. Now the TestTestTest View is at the top and covers… >>> More
Android RatingBar weirdness: Whenever I add a RatingBar to my layout, a bunch of the generated tags,

as seen on Stack Overflow - Search for 'Stack Overflow'
Whenever I use a RatingBar view in my layout, I suddenly get all kinds of compile errors. I'm using Android 2.0, but I've also tried 2.0.1, and 2.1, without joy. I also get a message: Shader 'android.graphics.BitmapShader' is not supported in Layout Editor, and an odd warning which may or maynot be… >>> More

Related posts about threading

WebClient error when using a thread in .NET

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm having a very weird error using the WebClient class in .NET 4. The app simply downloads some files off the internet and provides output on a textbox (the GUI is WPF). The method that does this is the following: void DownloadFiles(object files) { fileL = (List<string>) files; foreach… >>> More
Silverlight Threading and its usage

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello Experts, Scenario : I am working on LOB application, as in silverlight every call to service is Async so automatically UI is not blocked when the request is processed at server side. Silverlight also supports threading as per my understanding if you are developing LOB application threads are… >>> More
Partial Trust in WPF 4

as seen on Stack Overflow - Search for 'Stack Overflow'
I've started a new project in WPF 4 (.NET 4) and trying to see if I can run it in xbap mode. I need to run the application in Full Trust with the new mode made available in .NET 4 which asks the end user if the full trust application should be run. I've set the "Security" mode to "Full Trust" application… >>> More
TypeInitializeException on MVVM pattern

as seen on Stack Overflow - Search for 'Stack Overflow'
System.TypeInitializationException was unhandled Message=The type initializer for 'SmartHomeworkOrganizer.ViewModels.MainViewModel' threw an exception. Source=SmartHomeworkOrganizer TypeName=SmartHomeworkOrganizer.ViewModels.MainViewModel StackTrace: at SmartHomeworkOrganizer.ViewModels… >>> More
WebClient error when using a thread in .NET 4

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm having a very weird error using the WebClient class in .NET 4. The app simply downloads some files off the internet and provides output on a textbox (the GUI is WPF). The method that does this is the following: void DownloadFiles(object files) { fileL = (List<string>) files; foreach… >>> More