Android :: ActivityList - Loading Data From Network Best Practice
Sep 29, 2010
I have multiple ListActivity(s) with a custom ArrayAdapter. I have to load an XML file from the Web, and the user moves to a new activity by selecting a list item.
What is best practice for:
Displaying a loading indication to the user.
Threading the networking stuff so that the user can cancel the loading of the data if need be / move to the previous activity.
Example/source code would be greatly appreciated - I've used http://www.helloandroid.com/tutorials/newsdroid-rss-reader as an introduction, however it doesn't display a loading indication.
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Apr 25, 2010
I'm running into an IllegalStateException updating an underlying List to an Adapter (might be an ArrayAdapter or an extension of BaseAdapter, I don't remember). I do not have or remember the text of the exception at the moment, but it says something to the effect of the List's content changing without the Adapter having been notified of the change.This List /may/ be updated from another thread other than the UI thread (main). After I update this list (adding an item), I call notifyDataSetChanged. The issue seems to be that the Adapter, or ListView attached to the Adapter attempts to update itself before this method is invoked. When this happens, the IllegalStateException is thrown.If I set the ListView's visibility to GONE before the update, then VISIBLE again, no error occurs. But this isn't always practical.I read somewhere that you cannot modify the underlying this from another thread--this would seem to limit an MVC pattern, as with this particular List, I want to add items from different threads. I assumed that as long as I called notifyDataSetChanged() I'd be safe--that the Adapter didn't revisit the underlying List until this method was invoked but this doesn't seem to be the case.
I suppose what I'm asking is, can it be safe to update the underlying List from threads other than the UI? Additionally, if I want to modify the data within an Adapter, do I modify the underlying List or the Adapter itself (via its add(), etc. methods). Modifying the data through the Adapter seems wrong.I came across a thread on another site from someone who seems to be having a similar problem to mine: http://osdir.com/ml/Android-Developers/2010-04/msg01199.html (this is from where I grabbed the Visibility.GONE and .VISIBLE idea).To give you a better idea of my particular problem, I'll describe a bit of how my List, Adapter, etc. are set up.I've an object named Queue that contains a LinkedList. Queue extends Observable, and when things are added to its internal list through its methods, I call setChanged() and notifyListeners(). This Queue object can have items added or removed from any number of threads.I have a single "queue view" Activity that contains an Adapter. This Activity, in its onCreate() method, registers an Observer listener to my Queue object. In the Observer's update() method I call notifyDataSetChanged() on the Adapter.I added a lot of log output and determined that when this IllegalStateExcption occurs that my Observer callback was never invoked. So it's as if the Adapter noticed the List's change before the Observer had a chance to notify its Observers, and call my method to notify the Adapter that the contents had changed.
So I suppose what I'm asking is, is this a good way to rig-up an Adapter? Is this a problem because I'm updating the Adapter's contents from a thread other than the UI thread? If this is the case, I may have a solution in mind (give the Queue object a Handler to the UI thread when it's created, and make all List modifications using that Handler, but this seems improper).I realize that this is a very open-ended post, but I'm a bit lost on this and would appreciate any comments on what I've written.
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Mar 2, 2010
For my CS bachelors I am doing a Senior project using android and google maps.My vision was to do a (relatively) simple Dijkstra shortest path using google maps road data. I was going to add elevation change along with 2D distance. I am doing well playing with maps in android but I am completely stumped trying to access google maps data in any sort of searchable form.How would I go about accessing the data for say intersections of roads (lat/long) in a particular area?There has to be a way to pull that data in some sort of tree form. It seems like it may be possible with kml?Any pointers would be awesome.I want my paths to follow roads but If i cant this is going to turn into an orienteering application fairly fast.
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Jun 23, 2010
to start with I've gone through the entire notepad tutorial, I'm a professional game programmer who has some extra time. (though most of my time has been in C++, I did take a year or two of Java classes in college, and remember some of it). I'm not sure the site is a good site to ask questions like this.. If someone has a Forum that might be a good place to ask these newbie questions, please feel free to point me in the direction. I've examined a few of the samples, and think I've a grasp of what I want to do. I've a three to four project plan for some Android releases to sharpen my skills, but since this is my first project and I have never really developed for a mobile phone or the android before, I'd like to make sure I have a solid plan.The first project is an example of the license plate game, however I want to do a few things to change it. Heck maybe when I'm done it'll become a bingo style game, with bluetooth connectivity, you never know. The base idea is I want to offer a list of states, with checkboxes next to them. so to do this, I'll be starting with a Linear List layout similar to the note pad example, and then have a row that is only a Checkbox. I can use text and call strike through if it's been checked off. Perhaps offer an option to not show them if they are checked.
But I want the list to be generated from a set of lists. Maybe all of America's states, maybe reasonable American states (no Hawaii, no Alaska) maybe a North American list, (add in Mexico and some Canadian provinces), a European list, who knows. I'd probably have to have a pop up window that lists all of the lists I suppose using a radiogroup of some sort. So then as far as the data, after weighing options I think best solution is to make a database with two fields, "checked" and "name".I figure I can use the menu for most of the user interaction (aside from clicking on stuff we want to check off) with maybe a few context menu items, I understand how to make all of those already so I should be good. The question I have is what is the best way to populate the lists? Should I create raw data, and have different files for all the lists? Or is there some other way to do this? I've seen this done on the searchable dictionary, but I'd like to hear what people who have actually generated the data like this before. In addition is there an easy way to look at the sql database these applications create, or do you have to run searches on them and output the data? Finally any other suggestion or advice? I definitely want to try to get something like this on the market so I can see the full life cycle and see if anyone actually likes it. (luckily there's not a plethora of them already) but I also want a few people to look over my code if they're willing when I'm done to make sure I've done this right or at least not missing any basic mistakes.
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Jul 5, 2010
I seem to be seeing an issue with the data network access on the EVO. When it happens none of my applications get internet aceess and my mobile network status says "turning on". The only way I've found to fix it is to pull the battery. Any one else seeing this? If so is there a better fix than pulling the battery?
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May 29, 2010
My eris has always has pretty alright battery life, what I would expect out of a smartphone, if unplugged at 9AM it usually was running on its last leg around midnight. I've had it for over 5 months now, I've always had it activated on alltel, I installed the 2.1v3 leak before the official OTA was out and just lately it seems like there something very wrong with my battery life...
If I unplug my phone at 9AM within the past week and occasionaly check and respond to a text message, my battery had been down to almost 30% by NOON... what?..
I have noticed that if I disable Mobile Network (3g/1x data), the thing lasts all day and some... If I turn mobile network ON, I can't see that I have any network traffic or any apps running in the background that are syncing data at all... I've had google account sync mess up on me before and have to reset my google account because it gets stuck in a syncing loop, but its not doing that, already checked. Very weird.
Anyone thing it could be something wrong in my ##PROGRAM#/##778# provisioning menu, maybe something got changed?.. Maybe it could be do to Alltel's AT&T merger that's happening right now, maybe some 3G tower's radios are turned off or something...
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Jan 1, 2010
I'm trying to load the parsed HTML data from an rss feed using a WebView, but the webview claims...
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Oct 8, 2009
I just tried a stupid approach and it crashed my app... Basically I have an activity that has three tabs (containing three activities). Each of the tabs gets its input from an xml file downloaded off the net. Everything is fine but when I start my app, it has download the xml file and there's a "wait" time for this.I managed to get around this by adding a splash screen. It looks beautiful but the problem is when I click on the second tab, it still has to get the list off the net, so it looks ugly now... It waits before displaying the list. So what I did was design an AsyncTask that just downloads the xml file. In my main activity, I spawn two tasks initially and send the URL and Intent as parameters. And inside the activities that start inside the tabs, I use a wait(). Inside the AsyncTask, after it is done with the download, I notify the Intent using notify(). This crashed! Of course, I didn't expect it to work but just wanted to try :) Writing it so that I can either get a feedback as to why this failed or to prevent others from wasting their time on this...Now, I am sure many face the problem of a "wait" time inside the tabs. How do I solve this? I am thinking of either dimming the screen and then displaying a series of toasts or display a progress indicator inside the tabs or pre-fetching the xml files... I don't have a clue on how these can be achieved.
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Apr 10, 2009
I have a message application so that on view 1 is displayed a list of messages and when you go to view 2 (subactivity) you can send a message. I want the program to work so that when you hit the android back button, you can go back to view 1 and see the list of messages including the new message. Right now only the old data is displayed, and I noticed that displayContent() is not called when going back which I assumed it would. Is there any way to specify that when the back button is hit, to call displayContent() again on the previous activity?
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Aug 1, 2010
I have got list that is filled with data from internet.
Datas are downloaded in chunks. At the end of the list next portion of data is downloaded and added to the list.
I'm detecting list end with help of onScrollListner:
CODE:........
I would like to addLoading... row when datas are being downloaded. Something similar to Gmail loading row at the end of the list.
I know that I can hack adapter.getCount() to return size + 1 and force adapter.getView to display loading... at the end of the list.
How can I do that in more elegant way?
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Jan 20, 2009
My application needs to load and process some data at the startup which delays the displaying of the GUI quite a bit. I addressed that problem by starting a new thread to load and process the data. It solves the problem nicely, but is there a better way to do asynchronous processing in Android applications that I missed?
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Dec 1, 2009
I just purchased my Driod on Wednesday. I took it back today because it kept on freezing. They gave me a new one, but for the last 6 hours it has been "loading data, Please wait...". The Verizon store had no clue what was going on. It is in the task bar.
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May 27, 2009
when I load external web page, image or javascript file from local webpage. I can't see external image and can't load javascript or webpage. But I can only see local image. Why I can't load external javascript, webpage or image? Here is the HTML source. (of course, I filled right [daum open API key])
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http:// www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html> <head> <meta
http-equiv ="Content-Type" content="text/html;
charset=UTF-8"> <title>Daum 지도 API</title>
<script type="text/javascript"
src="http://apis.daum.net/maps/maps.js?
apikey=[daum open API key]" charset="utf-8"></script> </head> <body>
<div id="map" style="width:600px;
height:400px;
" style="border:1px solid #000">
</div> <img src="http://4.bp.blogspot.com/_2-7AdSkZA7I/RlCnDhD3ZfI/ AAAAAAAAE9U/LEHMtyVLdY8/s400/CutyTale10.jpg">
<img src="file:///android_asset/coffeebean.jpg">
<script type="text/javascript">
var map = new DMap("map", {point:new DLatLng(37.48879895934866, 127.03130020103005), level:2} );
</script> <iframe src="http://www.daum.com" width="300" height="150"></iframe> </body> </html>
and I use this Activity source
package bo.my.android.test;
import android.app.Activity;
import android.os.Bundle; import android.webkit.WebView;
public class OpenAPITest extends Activity {
WebView webView;
/** Called when the activity is first created. */
@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);
setContentView(R.layout.main);
webView = (WebView) findViewById(R.id.webView1);
webView.setWebViewClient(new DaumMapClient());
webView.getSettings().setJavaScriptEnabled(true);
webView.loadUrl("file:///android_asset/daummap.html");
//webView.loadUrl("http://www.daum.net");
} }
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Jun 12, 2010
I have got an htc hero device and would like to install my apk on it. It successfully installs my apk but without the database it is using. My database is populated prior to running the application, so it runs ok on the emulator. But I couldn't load my data on the real device and the apk is displaying forse close error. How to load my data on the data folder of the device including every detailed steps?
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Oct 7, 2010
I just received a warranty exchange Samsung Vibrant, & I am currently in the process of putting all my apps onto it. I have the widget on my home screen. The widget seems to be working, but the "loading data please wait" message is still displayed in my notification drawer & the little circle of dots is still in the task bar up top.
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Mar 4, 2010
Does anybody have an example of lazy loading (about 10,000 items) an Android ListView from a Sqlite databse?
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Nov 25, 2009
I have a message -- saying Loading Data, please wait -- but it's been a long time. What does this mean? How can I make it stop?
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Feb 7, 2013
I'm pretty new to Android development and I just hit a brick wall in the development of an app, I'm currently working on.
The problem is that I have a list of locations (states), and when one is selected, a list of cities from that state is loaded via http request and JSON and then is supposed to be inserted into a listview in another activity.
So now I have the StateList activity and the CityList activity. Currently, the statelist activity starts the citylist activity via an intent and gives it a state name. Then, the citylist activity uses that name and requests data from a server via AsyncTask. As result I get an array of City objects, which are supposed to be inserted into an adapter for a listview.
Now begins my problem: I don't want the second activity to show up before all data is loaded. I also don't want the first activity to do the request and then have to transfer the whole result to the second activity using intent extras.
So what would I have to do now to have the second activity load all the data and only then really show up? I tried only setting the content view after receiving the data, but since the base class onCreate() is tied to some manipulation of the layout, I would also have to call onCreate() at that point, which is not allowed.
Here some code snippets of what I tried already:
The onCreate() method of my second activity (which is supposed to hide):
[high]protected void onCreate(Bundle savedInstanceState) {
requestWindowFeature(Window.FEATURE_NO_TITLE);
// send request for citylist data
CitylistRequest request = new CitylistRequest(this, new State(0, getIntent().getExtras().getString("state")));
request.execute();
[Code]...
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Jan 4, 2013
I download apps from play store, amazon appstore and other places..
When I restart my phone, Some apps (no matter where are they from (play, amazon, etc.)) They stop working.. they dont work anymore.. and I will have to re install the apps again and loss all data
And also some apps that still work, they start like its the first time I am starting them and all data in them are lost..
I tried multiple things to fix this like I factory reset my phone and also tried to flash new version of stock rom but I still have this problem.
My device: Galaxy Note 2, jelly bean 4.1.2, rooted (no custom rom indtslled)
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Oct 28, 2009
Is it possible to use the cellular 3G data network while connected to WiFi? I want to create connection through the 3G network while WiFi is also connected.
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Feb 12, 2009
Does SDK 1.1 support an easy way for me to know what network data is sent/received?
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Sep 15, 2009
I needed to call a remote service. The service basically fetches data from the network. I am bind the connection once,and then I unbind the connection when the user is no more in that page. Everything works fine.Except that when I call the sa,e remote method for 17th time,it just does not call the service at all.It neither throws the DeadObjecti Exception. I have run out of ideas.Is there anything that I may be missing.
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May 4, 2009
I want to display a fancy 'loading' image at my app's startup time.
The problem: my startup code is mostly GUI related, hence needs to run on UI thread.
Is there a way to do both - that is run UI-related code on UI thread while an image is displayed to the user?
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Mar 13, 2010
Does Android MediaPlayer can only work with file sources? I would like play media (video) from a network stream, but the stream comes in a non-standard protocol, so I have to somehow feed Android MediaPlayer with the data only. Is there anyway to do that? I found a few web pages suggesting using a temporary file for the buffered media data etc. but I would like to minimize the I/O usage as much as I can, so I'm looking for a API only solution if there is any? how about JNI? but looks like the permissions going to be an issue with that also.
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Nov 22, 2009
I have had some issues concerning turning data management back on. Since I only have 250 MB included in my plan, I would much rather have the phone on wifi only when I'm at home Problem is, when I turn data network back on, it says "network not available". The only workaround seems to be turning the phone off completely and rebooting. SLOW.By the way, this happens both with the excellent app Quick Settings and the normal Parameters Phone App.I saw someone having similar issues regarding Wifi On/Offwith a Sprint Hero.
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Jun 22, 2010
My dad works in a secure building and needs a phone without a camera. He's with ATT and uses a dumbphone. He wants an android phone he can swap his sim card into while not at work. He has neither a data plan or a texting plan because he doesn't use them. He's considering an unlocked Legend or N1 if he can find an app/widget that will disable the data network radios on his phone, so he can only use the wifi. Would this work, or are there better apps/widgets you guys know of?
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Jul 18, 2010
It was thread about forcing your evo to roam on 3g data network. I was able to find threads about the hero but now the Evo. VZW works great at the cabin but sprint I have to walk out to the street and it will not roam onto VZW for some reason.....I have goggled and searched all the usual forums.
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Jun 7, 2010
So I've been using my phone for a few days now, both at home, at work and a few other places around town. So far Sprint's network has been unusably slow.Is this normal?For instance, 3G seems to be capping out around .5mbps, often closer to .2mbps, with tons of packetloss. By comparison, on AT&T I was consistently getting 1.5 and 1.8 in the same areas.For anyone that had Sprint before the masses of early Evo adopters deluged Sprint's network, what was your experience?Does .5mbps seem about right?Am I just expecting too much?
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Jun 25, 2010
cannot use sprint data network after using wifi. tried turning phone on and off.. still didnt work.. disabled everything.. wifi.. 4g.. bluetooth...
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Nov 5, 2010
Seems all the posts are about the opposite but I rooted and things were good, installed leedroid last night and just recently turned off my wifi and that's when I noticed that I had no data? I'm on Telus and far from using all of my plan. Very odd! Re-flashing with "AuraxTSense v8.0 HTC Sense 2.2" I do get the "limited service" warning at start up.
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