Android :: Views - ListViews And Adapters
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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Jan 7, 2010
In my ListActivity, I need header and footer views (on the top and bottom of the list) to be used as previous page and next page buttons on my list, respectively, because I want to display only 20 items at a time.
I set my header and foot views by doing:
CODE:............
This works fine, but I need to dynamically remove and add these header and footer views, because some pages of my list may not have a next page button or a previous page button.
The problem is, I cannot call addHeaderView or addFooterView after I have called setListAdapter.
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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 7, 2010
I am not very familiar with android coding so try to help me on a easy way.
The problem:
I have 2 Listviews and a onClick event handler.
How can i find out on which listview the user currently clicked?
public void onListItemClick(ListView l, View v, int position, long id) {
'Approach: if listview1 is clicked then FUNCTION1() else FUNCTION2()'}
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Jan 6, 2010
I have a simple ListView and on that ListView I have placed a number of custom defined Views. The CustomView has ImageView and two TextViews.
The CustomView also has a "stateful drawable" as background, so that the background image (a 9-patch) changes if you press the Row in the ListView. When pressing the Row, the background image changes to a Red-ish thing.
The problem is that when the background changes from the default greyish, all the Views in the CustomView (ImageView and TextViews) still have their greyish background and thus creates very ugly greay boxes on top of the now redish background.
What is the best way to solve that problem? I hoped that such things were handled automatically (as it is done in for example .NET), but I was wrong it seems.
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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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Nov 16, 2010
I am implementing a music player application in Android. My play list selection screen is implemented as a tab selector widget which contains a ListActivity inside each of the tabs: Artist, Albums, Songs.
I want to update the ListView in each of the ListActivity when I delete an item from any of the lists.
i.e. When I long press an item in the Artists list a context menu is drawn with "Delete Artist"
And it should delete all the songs from this artist in the Songs ListView, delete all the albums by this artist in the Albums ListView, and finally delete the entry for the artist in the Artist ListView.
Each of the ListActivity has its own fillData() method, which updates the ListView when the button in the context menu is pressed.
How can I call the fillData() method of the Albums ListActivity after I update the ListView inside of the Artists ListActivity?
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Feb 28, 2010
I want to populate a table, defined in layout xml file through the programmatic way. I have define Table with a single row defining its header, with all the attributes set. Now i want to know a way so that i can just replicate that header row in the table with new content.
I tried using inflator inflate(int,view) method, but at runtime it showed up with error.
Here is the XML code for the layout file defining the table
CODE:.................
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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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Mar 6, 2010
I have the following XML code:.................
The idea is to change the views, whenever I press one of the radio buttons. When I press a button the first time everything works out fine, but the second time I press a button, I get an IllegalStateException, and I can't quite see why I'm getting this.
Also, the Activity seems to set all my global variables to null, which is why I have to create them every time I switch from portrait to landscape or vice versa. So I would like to know if there is a way I can save my views in the Bundle, or any other way in which I can permanently save my views, so I don't have to add or create them every time, I flip the phone. And whenever I flip the phone, it seems that it rereads the main XML file, causing the RadioGroup to be set to 2D even if the 3D button is checked. This is because I've said the 2D button to be checked from when the app is first created, but I would like to also save the state of that RadioGroup.
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Jun 16, 2010
How do you align views relative to the "middle" part of another view? I think it is best explained with a pic of the UI I'm trying to create in android.
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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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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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Jan 25, 2010
Is there any way to query a root view of an activity for all of its child views even before the root view or its children have been inflated? I guess what I'm looking for is whether a view knows ahead of time what children it will have before it gets inflated, and can I get that list in some way. Bizarre I realize, but I think it will help me with some unconventional automation testing I'm working on. I haven't found anything in the API like this.
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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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Mar 7, 2010
Let's say I have a LinearLayout, and I want to add a View to it, in my program from the Java code. What method is used for this? I'm not asking how it's done in XML, which I do know, but rather, how can I do something along the lines of (One View).add(Another View) Like one can do in Swing.
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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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Sep 7, 2010
I have a ListView, and within each list item I have some TextViews and a CheckBox. When I check a CheckBox and my onCheckedChangeListener fires, everything works as it should. However, random other checkboxes get checked once one is checked. Here is an example.
If I click on the first CheckBox:
8 is checked.
15 is checked.
21 is checked.
27 is checked.
33 is checked.
41 is checked.
Then if I scroll all the way up, none are checked until 6. The next being 13.
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Apr 25, 2010
I'm trying to figure out how it's been designed. How it holds its items? How do I get a hold of the scrolling container? How can I know it's exact scrolling position? How can I scroll it to an exact position?
I want to have all the current benefits the ListView provides plus detailed scrolling control... How about animating from x to x+100 scroll position?
Maybe I need to create my own ListView? Where do I begin?
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Nov 18, 2009
Firstly, I have found many examples of how to grab data from a db and place it into a list, however this seems to be all for ListActivites.
My list is part of the UI and therefore I can't use a ListActivity because it does not consume the whole screen (or can I?).
This is the UI:
CODE:........
So, from what ive read I need to grab the data from the db, then place it into some sort of array then use an array adapter to fill the list view. Is that correct? If so, is there some sample code because all I can find is code releated to ListActivites.
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May 15, 2010
I am writing a software that i have to drill down on content a lot. For example when the program starts a listview is displayed. When user clicks on an item, then a second listview must be displayed. For example:
Select Continent > Select Country > Select State > Select City > Select Address
What is the best way to do this (less memory, faster, easier to code etc)? To create multiple listviews with multiple adapters? Or 1 listview with multiple Adapters? Lists are loaded from an external XML File.
So far i am creating a new adapter and setting it to the listview. How do i create a second listview and after clicking on 1st listview displaying the second one, with animation. Any examples? Extend my class to ListActivity or Activity?
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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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Aug 13, 2010
Hello, I need to put several listviews inner a LinearLayout. The Listviews should be wrap content to adapt the listview to their items. I need have one only scroll with which I can scroll all the listviews. I know that i can't use a scrollview because the listviews have their own scroll (but i don't need the scrolls of the listviews because i have them in wrap-content). I thought maybe puting the listviews inside the LinearLayout I will hadn't problems with the scrollview, but it didn't work, the LinearLayout was fixed to the screen, the scrollview didn't appear and the listviews ended scrollable. Without the scrollview if i have the list in wrap-content, their shown properly but i haven't any scroll and i can't see the lisviews below the screen. Really i have had this bug for one month and i haven't found any solution,
My code:
CODE:............
JAVA
CODE:...............
How you can see i create the lisviews dinamically and i put indside the layout with a secttion header. if you have some doubt ask me I need find a solution soon.
Sample Image: http://www.freeimagehosting.net/image.php?6dea1468bd.png
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Oct 11, 2010
I wish to work with checked list views wherein only one item can be selected at a time. Some queries related to this:
1) Is it advised to work with CheckedTextView as the ListView items, or a combination of CheckBox and TextView?
2) If using CheckedTextView, the text comes first and the checkbox appears on right edge. Is it possible to make the checkbox come on the left of the TextView?
3) How can I make one of the items as checked in onCreate()?
I am using array adapter and calling setAdapter() to populate list.
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Aug 16, 2009
I want to show many listviews in one activity. Something like
Textview Listview TextView Listview ..........
Every listview has different type of adapter. For this, I made the activity class like:-
CODE:........................
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Jul 22, 2010
In my app, I have different activities with listviews. The datas come from a server with a REST method, and it's only done once, when I start the application.
The pattern that I'd like to set is to precharge all the listviews with the JSONs that I already have in local, and in parallel, launch a thread that get the new JSONs files with my REST methods, and then update the listviews.
For now, when I start the app, I parse my JSONs files, and build all the lists of objects. I access them later in a static way, from my lists adapters.
So I would like to know the best way to launch this REST thread, and update the listview. Should I use AsyncTask ? A service ? and then, when I update my local JSONs, I have to re-parse them, updates the lists of object, and call in my adapters NotifyDataChanged ?
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Mar 22, 2010
Can I have two ListViews on a single ListActivity? I have built the xml file easy enough, but the code around ListActivity, setListAdapter(), getListView() and the like, all seem to be designed around one ListView per activity. How to get 2 ListViews in one screen?
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Nov 8, 2010
I'm not looking for exact code here, just a direction on what to look for and what I should be reading about so I can figure this out. I have a layout that I would like to remain static, with only the listview changing depending on what's selected from the list. I've reloaded data in the list, but I would like the fancy transition animations between choices, and would like the app to go to the previous menu when pressing back.
Someone suggested using a viewswitcher, which seems like it'd be great, but I am still unsure about how to fill a listview in a layout with a regular row layout, then on selection do an animated transition to a custom row. Also, it seems the viewswitcher is limited to two views, so it may be a limitation when I want to go a few menus deeper. Preferably, I'd like to put each menu in it's own class so that I can handle filling it in that class, if possible...
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Mar 25, 2009
I am trying to design a UI which utlizes two ListViews on the screen at the same time. Is this possible ?
So here is a quick example of how I was intending to do this.
1) Create an XML which positions 2 ListViews one onto of the other each ListView having there own ID
<ListView android:id="@android:id/list" android:layout_width="fill_parent" android:layout_height="198px"
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