Android :: Scrolling Large Lists Of Cursor-based Adapters Is Faster Than Much Smaller Lists Of In-memory Adapters
Nov 3, 2010
I have an Android app that has both CursorAdapter based ListViews (backed by sqlite) as well as custom BaseAdapter based ListViews which are built on the fly from JSON pulled down from a server.
The data displayed in both is identical - an image and a couple of TextViews. My Cursor-based ListView has 3000 rows, the JSON-based ListView has about 30. However, scrolling down the list is significantly faster for the Cursor-based adapter. For the JSON-based lists, the data is all fetched before the rows are made visible. Images for both types of lists are downloaded on-demand.
I have both ListViews configured identically - both with fastScrollEnabled, scrollingCache and smoothScrollbar set to true.
I'm looking for leads on how to go about trying to figure out what's going on here and to potentially fix it so that the JSON-based ListViews as as fast as the Cursor-based ones.
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Nov 8, 2009
I'd like to dedicate this thread specifically to the evaluations and feedback for various Todo's, Todo Lists, Tasks, Task Lists, Lists, etc.I'd like to keep this separate from Notepads as I've dedicated that to another thread ( Notepads and Notepad's that sync - Evaluations and Reviews ).Doing a search for Todo's and Tasks on the Android Market comes up with so many results. Rather than downloading and trying out so many, I'd like to know which ToDo's and Task Lists, etc. are recommended.I've been searching for ToDo lists and Astrid is frequently mentioned. Other sync or link to Google Tasks or sync with Google as well.Other ToDo / Task Lists? What are some ToDo / Task you've downloaded and/or experimented with? Please comment on other such productivity Apps. Please indicate if they
1) Offer Multiple Lists
2) Folders
3) Sync
4) Email
5) Offer other unique features
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Apr 20, 2009
Just looking at options for data updating affecting items in a ListView and have hit a few issues/queries.
There seems to only be notifyDataSetChanged() and notifyDataSetInvalidated(). While I could use notifyDataSetChanged() I am most likely in my case to have the scenario where additional data has been added and it seems inefficient to say the data has changed, which can only be resolved by calling getCount() and then getView() for all displayed items where knowing the data has been appended would just require adjusting the scrollbar. Is there some way to achieve something similar to this as the market seems happy populating dynamically in a manner that seems to reflect my desired behaviour (unless it just refreshes it all that fast).
Next question is the situation where the data behind just one item has changed. For instance I may wish to download icons in a background thread, but display available information with a placeholder icon. The best idea I've had so far is to store a map of indexes and views in my adapter which I can check against then call getView directly myself to have the view recycled with the new data. I'd just need additional logic to handle removing the map when the view gets destroyed or when it's recycled in getView. Either a bi-directional map (do we have one of those?) or two maps. Is the above likely to be my best approach or is there something built-in/better to get it done.
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Oct 18, 2010
I have a list view which I'm trying to refresh to update it self when i add an element to the underlying array list.
Here is the code snippet:
CODE:.....
The arrlEvents is the underlying arraylist with the events, and im adding one event, trying to update the list view with notifyDataSetChanged(), but it doesnt work.
Here is the source code for the adapter:
CODE:...............
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Jun 18, 2010
When I try to charge my Evo off of my usb charging adapter from my zune, it either A) takes ~3x as long to charge, or B) won't charge at all. Does the USB wall adapter that comes with the phone have something special in it? I'm drawing a blank... I mean even hooking it into the USB of my computer as charge only takes forever too.
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Feb 10, 2009
I'm using an autocomplete box, with suggestions provided by a SimpleQueryAdapter.Not sure if relevant, but only difference I see is that, both in the adapter constructor, as well as in runQuery(), I use a cursor returned by SQLiteDatabase#query obtained via an SQLiteOpenHelper instance.Should I be using on these cursors or not?If I don't use managed cursors, then I get "leak found" warnings ("database was created [sic] but never closed").
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Jul 6, 2009
Currently I'm trying to find an efficient way to handle the following scenario. Please comment on my current implementations and all feedback is greatly appreciated! I have about 7 adapters with data. This data comes from database and some come from xml queries over the internet which are kept static in memory. In my current implementation I re-use one ListView constantly to display this data as requested by the user. Here are the questions: 1. Is this a proper approach? or should I have a ListView for every Adapter?
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Aug 4, 2010
I am having two different data in two different adapters.
Now i want to merge both data in a single adapter.
is this possible?
How can I do that?
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Mar 20, 2013
Alot of the MHL adapters are sold with "for Samsung galaxy S II" or "for Galaxy S3", but they look exactly the same, so are they model specific or can be used on Android phone?
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Aug 5, 2010
I have a ListView filled with twitter tweets. I made a custom Tweet class so I could store a special type number. So, I have the Tweet class and custom ArrayAdapter: Code...
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May 3, 2010
I am trying to display the text from json in a list view.But my problem is that i cant figure out how to display them in list view. I also want to get only some of the text from url(for example, alerttext and date). Can anyone help me in declaring the list adapter and list view in order to display the data in the way i want.
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Nov 26, 2009
Is there a tread where they list a list of apps and what they do ,rather than brows the market?
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May 17, 2009
How to set a few lists in one layout include their own data from DB?
Here is source code about set list in Android guide. List id is @android:list why the id must be android:list?, may I use my own id? If I can, how to set lists to main layout including their own data.
CODE:........
I want to set lists like this :
CODE:..................
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May 14, 2009
I want to set some lists in one layout, but I found it's only recognize the first <ListView . how to write xml file ?
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Jul 12, 2010
I'm new to android development but I have run through various tutorials and am slowly grasping how to develop apps. I modified the Tab Layout tutorial on the android dev website to fit my needs, and now I need to add a list on to each tab I have created. there are a total of seven tabs and each will have it's on specific list. If someone could point me in the right direction to adding a list per tab that would be great. Each tab has it's own class file, would I add the list items as strings in the strings.xml then add code to each tab's class file in order to populate the tab? This was the only thing I have found so far, but it hasn't worked.
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Aug 19, 2009
Does anyone know if it's possible to show a "Currently have no items" type view in a ListActivity when, obviously, you have no items?
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Sep 29, 2010
How can i add separator between the two lists on a single screen.
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Jan 10, 2010
I am trying to create a todo list application on android. I am stuck because at the moment I dont know the way to create many todo lists. I have created the GUI for one list, using listview. entries of the list are added by the user when running the application. Particularly i dont know how to pass a list object, if i create new one.
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Oct 12, 2010
I have a 3 buttons, say LanguageButton, CountryButton and PinCodeButton. When LanguageButton is pressed, I must display a list of languages. Similarly for CountryButton a list of countries and so on. Only one list is to be displayed at a time.
My question is whether it is better to define a single ListView in my layout or 3 separate ListViews for each list in my layout!
I tried to use a single ListView and set corresponding adapters when different buttons are pressed, i.e in onClick() of languageButton, I give setAdapter(languageArray);
But my doubt arose in implementing the onItemClick() of the list. Because what must be done whenfirst item is clicked in languageList is different from what must be done in countryList. Hence that would add to more code in the java file.
So I am just wondering whether I should simplify my onItemClick() code by defining separate ListViews, or should I simplify my layout and add logic to code?
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May 26, 2010
How to make lists look different than your everyday average black list or more graphically pleasing than you usually see in android apps. I've looked through google code but haven't found too many. I'm looking for different and eye catching lists. I hope this question isn't too generic. Also i'm open to anything, code, examples, blog posts, etc, you name it. I've really struggled with lists and making them look more snazzy. I'm talking more the code level not the graphics or icons used.
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Apr 30, 2010
I'm trying to make a text blast list - basically one contact that contains many contacts so I can instantly text message all of them. Any advice on how to do that on a droid?
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May 28, 2010
I was trying to delete a contact using the code in the docs:
CODE:.......
But Eclipse doesn't how to find "Lists". What import statement do I need?
Also, is there a more direct way to delete a contact?
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Sep 6, 2010
I'm new to android, and loving it. I'm after a twitter app, that specifically has a widget that can display a list, rather than just the main timeline. I've tried lots of the popular apps but haven't managed to find anything that ticks that box.
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Apr 1, 2010
I am trying to find an app that will keep a list of my books. I found one on Androlib calledBookWorm but I cant find it in the app market any other suggested apps.
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Jun 11, 2010
I want to view two listviews at the same time. This is not the problem!
What I don't know if it's possible is if I can have two different context menus for the two lists? And second, is there a way to check in which of the two lists the user has selected an item?
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Jul 10, 2010
Say I have a list of Strings with the elements:
"One",
"Two",
"Three",
"Four"
I want to center them in the middle of the screen but I want to do it in a way that the start of each word is next to each other.
Like this:
One
Two
Three
Four
Considering that the font probably has different length per character, how do I do this best in Android?
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Apr 7, 2010
I wish to send a list containing objects from server to client and vice versa through httpurlconnection. Elaborating the same, the list contains a set of objects which is defined both in the server and the client. Its just that the server queries a database and sends the object to the client which collects the same and displays it to the user. Please let me know if thats possible and if it is, how would I be able to accomplish that.
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Feb 3, 2009
How to get lists of email from contact application in android? provide me some sample code or tutorial on this.
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Apr 22, 2010
I'm developing a real-time informations about train. The application will connect to a XML plateform that will give the next trains with a station given. I'm a beginner in Android development, and I'm stuck to a class- problem (I think...).
In details, the problem is, when I start the application, the user get a screen with 2 buttons, one of them get the user to a new screen with stations list. But, my problem is, I can't put buttons and lists in the same class. I explain, to get a list on the screen, I have to put : "public class NextTrain extends ListActivity {" but the buttons function doesn't work (the app crashs). By the way, if I put "public class NextTrain extends Activity {" the buttons works but not the list (no crash, but the screen doesn't display anything).
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Feb 15, 2010
I'm working on my first Android app, and would appreciate any guidance to make sure I'm doing this the best way. Basically I want an Activity to list recipes. Eventually I'll have another Activity to display an individual recipe selected from the list, but I'm not worrying about that yet.
The list of recipes should show each recipe's title, description, rating, and date added. For each recipe in the list I'd like the title on the top left of the list entry, rating on the top right, description on the bottom left, and date added on the bottom right. I may want to add photo, icons representing properties of the recipe (e.g. vegetarian), etc. The makes me think that each item in the list should be a TableLayout.
With all that in mind, here's what I'm planning to write:
1. Write class RecipesDataAdapter extends BaseAdapter. Override the getView() method to return an instance of TableLayout. Populate each instance of TableLayout with two TableRows, the first row containing cells for title and rating, and the second row containing cells for description and date added. For now I'll just pass the Recipe instances to the adapter in an array.
2. Write class ListRecipesActivity that extends ListActivity. Override the onCreate() method to obtain instances of the Recipe class and call the setListAdapter() method with an instance of the RecipesDataAdapter class.
Notice that all this is done in code without any layout XML files. All the examples of Activities that I've seen use a layout XML file and call setContentView(R.layout.layout_name) but I'm not sure if I need to do that for this, or even how I would do that considering my main Activity is a list of non-trivial things (TableLayout).
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