After I press a button, Android parse a JSON file and pick the info it needs. Until yesterday, I was using an external library created by a user and it worked perfectly. But now, I don't want to depend on him, so I've searching info about Google's GSON. I've implemented this library with no problem, but now, after pressing the button that opens a new activity there's a delay.
This delay is due to the connection and parsing that are done before the activity shows.
How can I force the app to wait the Internet connection until de Activity is shown? It's a lil bit uncomfortable because after pressing the button, it seems that the app has frozen, but after all data is loaded, the new activity appears.
Thank you in advance!
Use AsyncTask or Handler for network operations. Do never put "long time" operations into the UI thread
Use asyncTask.. and if server communication is a success then show the new Activity or else exit..
it is possibl;e via Handler and AsyncTask see this How to set delay in Android onClick function you will get how to use Handler and see this for Asynctask https://stackoverflow.com/questions/7644567/need-a-simple-example-for-android-asynctask
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I have several AsyncTask in my Project to grab data from some given apis.
I followed the following steps.
1) execute an Async Task and try to grab datas from there.
2) check conditions for internet and server down
3) if any issue in api or internet or server then show dialog [custom from self made class]
4) dismiss button for canceling the dialog and go back to the working stage of `app may be even by closing the activity`
My problem is I want to keep a Button "Retry" such that it shall be re executing the AsyncTask.
I searched of passing AsyncTask but it seemed worthless as I concluded AsyncTask cannot be passed. And so I am forced to repeat same code cancel(true) for various times
It would be very useful if anyone could give me solution for it with this code re-use concept.
You cannot "retry" the same AsyncTask object - you can only call AsyncTask#execute() once. However, you could create a new AsyncTask instance when the user decides to retry the download task.
Solved The problem by using a retry button that creates the new object of class implementing Async-task and executing that new object.
I've got the following problem. In my app I'm loading data in an AsyncTask. The problem is, when the user now clicks on the icon to open the Navigation Drawer and opens up another fragment the app crashes. When the AsyncTask is finished the app doesn't crash. The problem that is encountering is, that when I switch the fragment (The fragments are always the same, just with another content dependent on the NavigationDrawer Item click) the app crashes.
I guess the problem is, that the async task isn't finished, I'm calling the same fragment again want to display different data.
So what would be my approach to handle this? Use for every different view a different fragment? I thought using the same fragment every time is much easier, since it's just displaying different data but the structure, layout etc. is all the same. Just the data that it gets is different.
I also thought about somehow "blocking" the user from doing any other actions while the asynctask but still show him that the app is processing. But that would be not the definition of an AsyncTask.
How would you approach it? Use different fragments for every different display? Or how? Block somehow? If a user clicks on an item of the navigation drawer the asynctask needs to stop all its actions (if some are done) and then restart doing all the actions. Is there a way to do it?
Please note that the fragment where the async is executed and the activity where the fragments are called are in two different files
You can either block the screen with a loading screen (not that good UX wise...) or you could cancel the asynctask when you change the fragment, in the destroy or detach method.
You didnt show the errors, but I would guess that the app crashes because you are trying to acess something in the asynctask onPostExecute method and it is no longer available...
I guess that it crashes because your AsyncTask is sending data to a class instance that doens't exist.You should change the Class that receives callbacks from asynctask. Anyway i can't give you a better answer till i will see your real code of AsyncTask ( at least onPostExecute() and onProgressUpdate())
use intent service to do that ask task means call ask task in a intent service that one is capable to handle background task without hang UI
I am creating an app MainActivity that can calculate a report from its database to be shown in ReportActivity. All report calculation is done in ReportActivity.onCreate().
When the user click on MainActivity-s menu "generate report" the menü remains open for 2 secs until ReportActivity.onCreate() has finished and the report becomes visible.
What is the easiest way to give the user some visual feedback?
I already found ProgressDialog onCreate that shows a progressdialog while doing all calculation in an AsyncTask.
I wonder if there is some easier way to give the user some visual feedbak that the menue was successfully clicked and that the device has not crashed.
in ms windows i would use a waitcursor (hour-glass)
I already tried to open a ProgressDialog() in oncreate of the ReportActivity
final ProgressDialog progressDialog = ProgressDialog.show(this, "MY Dialog", "Please wait...");
but it is not shown at all.
Update final solution:
As the answerss suggested I implemented an AsyncTask for the processing following this tutorial
based on this codesample
You need to move your long-running code into a background thread. Long-running code on the UI thread will lock up the UI, which causes the user to think the app is frozen/crashing. Look into using AsyncTask. This allows you to run a process on a background thread and also give visual feedback to let the user know that your app is working.
Design a layout with ProgressDialog. Use setContentView(Progressdialog). Count time for 2-4 seconds (you choice) again set your older layout in setContentView. Why don't you use AsyncTask?
Use a bar or circle activity indicator. From the official design guide:
Activity indicators are for operations of an indeterminate length.
They ask users to wait a moment while something finishes up, without
getting into specifics about what's happening behind the scenes.
I've got an app that uses ListActivity to give users a list of actions. When they click one I use an Intent to launch a separate activity.
My problem is that the actions that the app performs take about 20 seconds to finish, and since I don't want the user to receive that nasty ANR dialog, I tried to use AsyncTask to present them with a loading screen in the mean time. I tried using setContentView(R.layout.loading); on onPreExecute(), but it throws a NullPointerException which as far as I have figured out is due to the fact that loading.xml is not "a ListView whose ID is android.R.id.list".
So what can I do now? How can I show that loading screen? Is there a way around this pretty annoying situation? Any help would be greatly appreciated. Thanks!
I am not sure exactly what your use case is; you have a list of items that are populated immediately, and upon selecting one an action is taken? The action that is taken is to launch another Activity which performs background processing?
Or does it take that long to populate the list of actions?
If the former, you can use an AsyncTask for the long-running activity instead of an Intent to launch another Activity: in the callback you get for the click on the item in question, you would create the AsyncTask, and in doInBackground you would perform the long-running activity, with onPostExecute refreshing or manipulating your list as necessary.
Another thing to consider is using a dialog box to show a loading screen, if the loading is required to happen before you launch a new Activity.
If you can further describe your use case, I can help you more.
It's not the loading screen you need to have on the AsyncTask, it's that 20-second Activity initialization. I would look for a way to do all the setup in a background thread in a Service while the user is free to merrily bop around in other Activities. I'd try hard to find a way not to just stall the user for 20 seconds. Maybe take them to the target Activity and show them data cached from their last visit until the new set is ready.
Fire up and display your loading dialogs in your onCreate() of the Activity being called, then call Dialog.dismiss() in your AsyncTask's onPostExecute().
I have a comment activity that loads a Thread and sends some data to a server; the activity is immediately finished once the submit button is pressed.
The user is then free to do other things in my application.
When the server responds an AlertDialog is shown.
The problem is that since the initial context has been destroyed, my application crashes.
I tried getApplicationContext() but still get an exception.
Put your network stuff in a Service, then show a status bar notification instead of a dialog.
Take a look at AsyncTask
From JavaDocs:
AsyncTask enables proper and easy use of the UI thread. This class allows to perform background operations and publish results on the UI thread without having to manipulate threads and/or handlers.