I'm watching this video http://www.youtube.com/watch?v=N6YdwzAvwOA and Romain Guy is showing how to make more efficient UI adapter code using the getView() method. Does this apply to CursorAdapters as well? I'm currently using bindView() and newView() for my custom cursor adapters. Should I be using getView instead?
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I was using some of the code from DeskClock and found that when I tried to modify the CursorAdapter that newView was getting called for each item. (I actually wanted to add a divider and it seems like adding the dividers separately is better than adding them into a single listView)
If I have 3 items I get the following behavior:
CODE:.............
I would've expected newView/bindView to be called once per cursor item. But, that doesn't seem to be the case. This was kind of a problem for me because I wanted to select the appropriate view depending on the cursor data, but since bindView could be called before newView that doesn't work.
Is this some odd recycler behavior (or somehow normal/expected)? Or is there something broken with the code (I removed everything except the ListView and it's still doing this)? I'm not quite sure why you would try to bind views that haven't been created, and why newView gets called on the first item twice.
If someone has an easy way of adding dividers to ListViews I'd love to know. I was going to try to dig through the contacts example to see how they did it there if not.
In case anyone's wondering MergeAdapter was neat to mess around with and try (I'll use it in some other situations). But, I did just end up writing a single adapter that handles multiple views. It computes the type of each item (which is small), stores it in a map, initializes it at adapter creation, and updates it in notifyDataSetChanged.
Then you just need to have getViewTypeCount() return the number of possible views. And getItemViewType to return the type from the map (which is 0 based, so 0-getViewTypeCount()). If you can compute your type from the position you don't need the map, but doing this on the fly wasn't possible so I just pre/recompute when needed.
I will try to be specific if I can - please be patient, first time asker and relatively new to programming on this platform. Apologies if this has been asked/answered before - please link it to me. I have searched up and down but find other unrelated (to me at least) problems.
The real puzzler for me is that my app is crashing on my emulator but when installed on my phone (via upload of apk to phone and then using an AppInstaller app from market) it works.
The crash comes from a NullPointerException at the numbered line in the following code snippet (my code) of a custom list cursor adapter.
CODE:....................
The following error dump is created.
CODE:..............
Curiously I have been happily programming and debugging away all day and out of the blue a long working and bug free portion of my app now throws up this error.
I suspect it might be a problem with the databases, but really not sure - nothing seems out of place there. Up until today I had a database with only one table - today I added a new table which also has a "_id" field as the name autoincrement key field, which I read in the docs was required for android list adapters (if memory serves). Having some experience in coding and some minor experience with databases, that seems like a bad idea to me but I am uncertain of if that is the problem and/or how else to do it.
The crash I am listing here does not display or make reference to the data in the other, new table. The cursor does not contain any query data from it. In fact if I rename the key field "_id" of the new table to something else (ie "_blah"), the crash remains.
Like I said, if I upload the apk to my phone, it works.
I have tried the following on the emulator:
- restarting adb (and eclipse) - no result
- uninstall from emulator - no result
- destory AVD profile and recreate - no result
I am developing this under the Android 2.1 SDK, and have been for the last few weeks. I have only ever had that SDK installed, I am yet to update to 2.2.
Not sure what else I can say here - hoping somebody here has experience enough to shed some light on it.
Without a fix to this, I can anticipate a very slow development process here on out (assuming I have to upload to my phone to test new code changes...).
I am building a custom listview used to list contacts from the contact cursor into a list with two text view for the phone number and name of the contact as well as a place for the images. I am getting a nullpoint error when i try to setText for my TextView Even though i checked the variable to see if they contained a string I have no ideas whats wrong with it. Code...
View 1 Replies View RelatedI have a cursor adapter and the logcat is filled with above errors, as soon as I click on a view. I am already releasing the CursorAdapter's cursor in onDestroy().Is there any way to get information about when the cursor was opened?
View 3 Replies View RelatedI have made customAdapter (which extends BaseAdapter). I want to reuse the old views..
So I am checking:
CODE:........................
I have a problem with bindView() that has me puzzled. I am using it to customize each row, including setting icons, coloring the background and setting up listeners for buttons. It mostly works as expected, but not quite.
When I fill the ListView with SimpleCursorAdapter, I get multiple calls to bindView() for position 0, but only 1 call for the other rows. The problem is that when all is said and done, I have 2 rows (LinearLayout) created for position 0. Here is a sample log extract:
CODE:........
I use a view holder class to hold the view, position and other data so that when a button is clicked, I can retrieve the holder with view.getParent.getTag(). This all works fine. The problem is that there are two views for position 0, but it's the first one in the above logcat that seems to be displayed. My code which acts on the rows when a button is clicked (especially setting background color) does not reliably hit the position 0 row that is actually displayed.
I can see what's happening but I am at a loss about what to do about it. Why are two view created for position 0? Is it something that I can control? How? If not, how should I deal with it so that the results when I modify the views are predictable?
In all the examples I've found to manipulate each view in a ListView, the method always seems to be getView(). But these were never Adapters backed by a cursor. I decided to try bindView() within a SimpleCursorAdapter, and so far it works very nicely, especially with the cursor all set up for my use.
My question is, is this usage good practice, and could I run into a problem in future? My question may be dumb but I just couldn't find a good example code snippet that uses a cursor.
The problem is as follows: - My app is deriving from TabActivity that has 3 tabs - Each tab has a ListView - Tab1 is populated by an adapter that inherit SimpleCursorAdapter and overrided the bindView() method. This tab is displaying correctly. - Tab 2 is also populated by another adatper that inherit SimpleCursorAdapter and overrided the bindView() method. For some reason that I don't understand, the overrided bindView() is not being called. Thus the tab is not displaying correctly.
Here's my code fragment:
CODE:...........................
I am using setViewValue method of ShowViewBinder to access image inside row of listView. The idea is to load image from internet and display it inside row of listView.
To load image, I am starting new image loader thread, but what I discovered when debugging this code, for each row I am actually starting 3 or 4 threads. I don't understand why. The code in if (columnIndex == ...) is executing more than once.
My code goes something like this:
CODE:...................
Does the CursorAdapter run on a background thread and posts updates via the UI looper thread? If not what is the best pattern to load data asynchronously from a ContentProvider?
View 1 Replies View RelatedI am writing my own ContentProvider for my own application. And there is a ListView with a CursorAdapter pulling data from my Content Provider. My question is when there is a data change in my ContentProvider, how can I notify my CursorAdatper to requery the data and then have the ListView updated?
View 2 Replies View RelatedI have a list view with 2 buttons on each row. I am using a cursoradpater to populate the list. I am also using the view holder pattern on newview() bindview().
My questions are: where do i put the clicklisteners for the buttons knowing that the action for the button is different from the action of the list item itself? Do i keep the onListItemClick ?
Does anyone tried to use CursorAdapter with old and new api?
Do you have some code examples of such solutions?
I am new to Android development and have been following the tutorials available on the Android website. I am currently on the section of tutorials for Views, specifically the one for Grid Views: Hello, Grid View Tutorial.I am having trouble understanding how views are made through an adapter. I understand that you must override the getView() method in your adapter class and in this method is where you define how your Views are set up. What I don't understand is where does getView() actually get called? Perhaps I've got the wrong kind of mentality here, but in the code below (the Grid View tutorial) I don't see any calls to getView() (or any other things used in the adapter class such as getCount()).
View 1 Replies View RelatedI have a CursorAdapter attached to a ListView, the ListView contains checkboxes for every row. When I check/uncheck a checkbox in a row it will update it to a 0 or 1 in the database (This is working fine) I also have another checkbox in the same Activity that when pressed will disable all the checkboxes in the ListView [ setEnabled(false) ].
The problem is that when I press this checkbox the ListView checkboxes return to their initial state when I started the activity. It does not matter the number of checkboxes I changed during the activity.
However, if I press the back button and then re-enter the activity all modifications are saved because the Cursor is refreshed. I am calling notifyDataSetChanged() at the end of the the methods that disables all the checkboxes.
I also tried this for every checkbox in the ListView but it did not work (was unable to check a checkbox) Any ideas?
I'm trying to change the content of a row in ListView programmatically. In one row there are 3 TextView and a ProgressBar. I want to animate the ProgressBar if the 'result' column of the current row is zero.
After reading some tutorials and docs, I came to the conclusion that LayoutInflater has to be used and getView() - overriden. Maybe I am wrong on this. code...
I've made a customAdapter that accepts an ArrayList. The ArrayList contains a title and then a link. code...
I'm wanting to display the title and then have the on click listener to have the link. I'm having trouble however figuring out a way to do this.
I definitely have a memory leak problem and i'm trying to figure out there. After 6-10 config changes i'm getting out of memory in regards to BitmapFactory. I'm kind of suspect that this is going on within adapter. I have a listview . ListItems are an thumbnail image ( ImageView ) and TextView for text.
Here is the getView code.
CODE:..................
And get ThumbnailBitmap() is basically BitmapFactory.decodeByteArray ..
Is it possible that i'm leaking drawables ? Heap is not increasing by the way .
I have a ListView backed by a custom adapter based on a CursorAdapter.The cursor I give it is based on a list of Notes in the database (each note is a DB row).Everything works just fine until I delete a note from the database. I'm not sure how to properly update the cursor/adapter/listview to display the new data.I've read conflicting posts on using adapter.notifyDataSetChanged() vs cursor.requery() to refresh the UI, but neither of them seems to work in this case.The only way I've been able to refresh it is by creating a new cursor from a new query and calling adapter.changeCursor(newCursor).Could someone demonstrate the proper way to update the backing data and then the UI (with psuedocode if possible).
View 2 Replies View RelatedI have a listactivity as a startup screen in my application. Which is displaying database records using custom cursor adapter. On create I set the filterable flag - getListView().setTextFilterEnabled(true)
My cursoradapter overrides runQueryOnBackgroundThread which runs corresponding query. The problem is that after typing some text and hitting enter, runQueryOnBackgroundThread never gets called. However, when the item click in the same view launches another activity(detail view of the record) and I come back to the original list activity, hitting back button, then text filtering works just fine. I don't call setTextFilterEnabled anywhere except during the initialization process and I can't really find any other API affecting this behavior, so any guesses why text filtering doesn't work initially, but all of the sudden starts working when I come back to the list activity from child activity?
I'm trying to clean up some code and now I'm determined to get this seemless ListView updating working...
I want my ListView to be updated when I call notifyDataSetChanged() but nothing happens... I'm also passing the autoRequery flag to true when creating my CursorAdapter.
Cursor c = FavoritesHandler.getCategoryFavorites(getSQLiteInstance(), category); m_favoriteAdapter.changeCursor(c); startManagingCursor(c);
When I check my logs, when using ListView, I see, that getView() method of a custom adapter is continuously invoked on first 6 elements, even if I scroll to the very end of the list.
View 1 Replies View RelatedI have a list and i want to check is the view is returned so i can call loadingAnimation.start() to make a imageview insite listview animate
Let me tell you what i mean.. code...
I have a ListView with custom ArrayAdapter. Each of the row in this ListView has an icon and some text. These icons are downloaded in background,cached and then using a callback, substituted in their respective ImageViews. The logic to get a thumbnail from cache or download is triggered every time getView() runs.
View 4 Replies View RelatedMy application uses a list of media files on the phone, i.e. images, audio and video. It also allows the user to filter the list via some checkboxes in a menu, so the user can choose to show or hide each type of files. The way I've been doing this is by putting this in the adapter's getView():
// don't show unwanted file types if (cmo.hasType(MediaType.AUDIO_FILE)){
if(!prefs.getBoolean(PREFS_SHOWAUDIO, true)){ return new ViewStub(mContext);;
} }else if(cmo.hasType(MediaType.IMAGE_FILE)){ if(!prefs.getBoolean(PREFS_SHOWIMG, true)){
return new ViewStub(mContext);;
} }else if( cmo.hasType(MediaType.VIDEO_FILE)){ if(!prefs.getBoolean(PREFS_SHOWVIDEO, true)){ return new ViewStub(mContext);; } }
Which is quite effective in the sense that the list doesn't show those elements. However, the ListView still renders a 1px grey line between each View, even if they are ViewStubs, meaning I see a thick gray line whenever a group of consecutive items are filtered away. How can I get rid of those lines? Should I create a new data array, containing only the elements that should show a view?
I have a ListView displaying images on every element of the ListView, It works fine... but when I start to scrolling I have realized my image is downloaded again if it is displayed in the screen of my phone device!
How could I stop reloading the images or all the content of the in ListView again?
Or how could I avoid reading the getView() function again If I have already downloaded all its content?
How to invoke the getView method in the baseAdapter in Android from another WebService Bean?
The adapter in my code as follows, I extends the base adapter code...
The preference type of UI is used in many Google built-in applications for example Bluetooth , Wifi etc. And the getView of the preference is used to set the image or text to make it visible in the UI screen.
the getView for the pref type UI is defined as below in framework code : ->
CODE:..............................
Where the convertView is not getting recycled and every time whenever the user is scrolling the list up and down, convertVIew comes out to be null.Therefore by logic inflation of the UI also happens all the time in onCreateView().This is a kind of shortcoming in terms of memory utilization , hence in a discussion (MAKE YOUR UI FAST AND EFFICIENT) where Romain Guy has mentioned about the tricks to increase the app performance doesn't hold good for preference type of UI.
If you derive a class from ArrayAdapter for the purpose of customizing the views of listview items, and you vary the background color of those items by doing something like this in getView()...
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