I have 2 activities :
- activity A is gathering data from internet (it takes some time)
- activity B is building UI elements based on the data previously received (it takes some time too)
When activity A start downloading, the app enter a loading phase. When it's complete, activity B starts, so I have a transition between the views of A & B. Then B requires also a loading phase.
I have loading - transition - loading - result which doesn't look nice at all.
I would like to have loading - transition - result where the loadings of both activities are grouped.
So my question is : is there a way to start the activity but to delay the transition ?
I don't think you are going the right way about this. I would suggest just having one activity with a loader. Then use something like AsyncTask to load the data in a different thread. Update the UI as the data gets loaded and then when everything is done remove the loader. You should use multiple threads to do work that takes time because otherwise your UI will freeze. Looking at what you said above, I don't see why you would need two activities.
You can use an ActivityGroup: http://developer.android.com/reference/android/app/ActivityGroup.html
This would allow you to achieve what you want. I don't think it's possible without it - (if you really need to wait until all UI elements representing the data are drawn. Otherwise I would suggest to follow Amir's advice below).
You put both activities into the ActivityGroup, but hide B at the beginning (visibility=gone). Then you can swap the visibility / do the transition once the data is loaded and the UI for B is built.
I'm curious though what kind of layout/UI you have that takes so long to build, if the data has already been preloaded in A.
Related
I'm developing an android app that is going to be used on a information screen. This app contains 5 (weather, next run, opening hours, etc...) activities, the plan is to loop through these activities with a timeinterval. So it starts with first activity, sleeps for like 5 seconds and then jump to next activity, and when it comes to the last activity, it should start in the front again.
What is the best solution to create a navigation system like this? Have Android some special features for things like this, or is the default startActivity() the only way?
And there is a little twist with this, some of the activities needs to retrive data from external sources by HTTP. So the activities must be done with data-query before it starts the activity.
You use startActivity to swap between activities. After you are finished with an activity, remember to call finish() - otherwise there will be a lot of instances of the same activity.
But if you want something like an information screen, you could use a single activity but use Fragments. That way you simply inflate a single fragment, and keep a timer to swap between them. You can still show the same content, but there are some differences between activity and fragment in inflating and finding the views by id.
I have 2 Activities.
First one is a list view and when i choose one, detail information Activity is opened.
Second one requires complicated loading process along with ViewPager.
The problem is that there are too many data to load & progress(includes Google Map data) and it makes my beginning animation's FPS terribly laggy, which is not good at all.
I decided to wait in the first Activity screen with central progress circle until second one is fully loaded.
How can I request Android to 'pre-parse' another Activity before being displayed?
I think the best way is after clicking on an item in the listview (first activity) start an asynctask to fetch your data. Then this task is complete, start your second activity passing a bundle with the data previouly fetched
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
As my app (game) is getting larger and larger, I've started to encounter a problem.
I have a menu activity with a 'start game' button - when the user presses this button, it starts the main game activity - now in this activity, I'm creating bitmaps etc in the constructor but there are so many that now when the activity starts, there is a slight delay - about 2 seconds - before the game actually starts.
I'm clearly doing something wrong - please could someone advise how to get around this so the delay (which clearly, has to happen) - isn't noticed by the user.
Load the ones you need immediately right away. Load the rest on a background thread (probably an AsyncTask). If you need one before it may be loaded, either pause or put up a loading screen as needed.
You could start loading the bitmaps in the background of your menu activity, or even when your app is created using a background thread or AsyncTask. You'll still need a loading screen of some sort in case the user navigates to the main game activity before you're done loading all of the bitmaps though.
You can also kick off an IntentService to load the bitmap. When the bitmap is loaded the IntentService can send a broadcast using LocalBroadcastManager. Then each component that cares about a result can register a BroadcastReceiver with LocalBroadcastManager.
I know it sounds crazy that someone is using runOnUiThread inside AsyncTask. Somehow, it is working for me but I wanna know if it is an acceptable and robust approach or not. Here is the scenario:
I have an app in which after successful login, user is rendered to next screen. In this new screen, 3 different methods are loading different types of data from a web server. These methods are:
getMembersForList() : It loads the list of community members and shows it in a listview.
getProfileData() : It loads the profile of logged in user and shows his name , image etc on the screen.
getNotificationCounts : It loads the count of new notifications for the user.
I applied 3 different approaches for it :
(1) Calling all 3 methods simply in onCreate i.e. no exclusive thread is being used for any of the methods . In this case , the transition from login screen to this screen becomes very slow and black screen shows up for some time before this activity shows up.
(2) Calling getMembersForList() on UI thread and the other 2 methods on exclusive threads. In this case transition becomes fast and list shows up quickly but Notification counts and username etc. don't show up because WrongThreadException occurs saying that this thread can't touch other thread's views (TextViews for username, notification count etc. which are declared globally) . The same thing happens when I start these threads from an AsyncTask as well.
(3) Calling getMembersForList() on UI thread and then starting an AsyncTask in which the other 2 methods are being called in "runOnUiThread" inside doInBackground() method. This solves both the above issues. Now the screen transition is faster and the WrongThread exception is also not occuring.
So far the approach-(3) is working good for me but I am not sure if this is the right way to do it because runOnUiThread and AsyncTask are 2 completely opposite things. Can anyone please clear my doubts about this scenario. Thanx in advance.
Yes, use-cases like this are a big reason why the runOnUiThread() method exists in the first place. The idea is you allow your background thread(s)/AsyncTask instance(s) to run your lengthy operations in the background, and then provide a simple hook that they can use to update the interface when they have the result (or at arbitrary intervals, as different pieces of the result become available).
As long as that's what you're doing, then your usage is fine. What you want to avoid doing is performing a lengthy operation on the main thread, either directly or indirectly by passing in some lengthy operation from a background thread.
Of course you don't have to do it that way if you don't want to. You could use postExecute() instead. Or you could store the result somewhere and then use any sort of message-passing API to notify the main thread that the result is ready, and so on.
I would advice to run all the 3 calls in the asyncTask, and update the UI in the postExecute() of the AsyncTask after the background taks is complete, postExecute runs on UIthread so you need not call anything explicit to run them on UIthread.