In a ListView/CursorAdapter, it is easy to go from a position to an itemId
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Is there any way to do the reverse mapping? From an itemId, get its position in the list?
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Sample code there is a method getitem(position) in the class of image adapter which returns null for the sample example. However, this method is important and is supposed to return the corresponding data item of the image adapter. For example the image adapter could generate a series of customized image views by magically calling the getview method. How could we implement the getitem(position) method under this case to help us gain access to these customized image views?
View 2 Replies View RelatedI have ListActivity to show a custom list. The adapter for this list is a complex layout only known for each row at runtime depending on data gathered in a previous activity. The question I have is simple. I know it takes 4-6 seconds to prepare the adapter for the rows that will be visible (first 10), however I would like to let the user know by means of the empty list functionality or otherwise. At present the ListActivity is launched via a button on a previous activity and when that button is clicked the new activity will not be loaded until the adapter is completed, and the user is stuck with the previous activity until this happens. Code...
View 5 Replies View RelatedI have a listview displaying my data.Ok. I want to set the scroll position in a position of my choice, but I just cant do it. I used :
myListView.setSelection( anyPosition ); myListView.setSelected(true); and has not worked. I also tried : myListView.scrollTo(0, PositionY); and myListView.scroolBy(0, PositionY);
and there's a strange behavior, this two methods doesn't put the scrool in the "PositionY", it made the "PositionY" be the first position in the list, cutting everything that exist before.
I have a long listView that the user scrolls around and then returns to the previous menu. What I want is that when the user opens this list View again the list to be scrolled to where the it was previously left. Any ideas on how this can be achieved ?
View 2 Replies View RelatedI've implemented a custom ListView and Adapter, and sometimes I receive IllegalStateException exception:" ERROR/AndroidRuntime(3575): java.lang.IllegalStateException: The content of the adapter has changed but ListView did not receive a notification. Make sure the content of your adapter is not modified from a background thread, but only from the UI thread."
Here is some code example: Code...
I have a ListView that is controlled by a standard BaseAdapter.When the user clicks a button, I want the ListView to Scroll into view the 100th record.How is that done?
View 1 Replies View RelatedIn my app, my main class extends ListActivity and calls a fillData() function to reload the list whenever changes are made. I'm still getting the hang of this, so I borrowed that concept from the Android Notepadv1-Notepadv3 tutorials. Everything works great, however whenever I need to change the list (remove an item, re-sort it, edit an item), the ListView refreshes and loses its scroll position. The scroll position is reset to the top after each fillData() call.
It appears to be resetting the scroll position to the top because I'm using setListAdapter() each time in fillData(), setting it to a new SimpleCursorAdapter. How can I get the list to "update in place", where the scroll position is seamlessly maintained to the user? I tried heading down the "items.changeCursor(cursor)" path, but that didn't seam to do much for me.......................
I've just added a header to my ListView and I have to change a bunch of code because the header essentially becomes position 0 (Meaning the Cursor indices of my CursorAdapter do not line up with the indicies of the list. They are off by 1 now). Why? This seems a bit silly to me.
The only reason I can come up with is that a developer may want to access the header. Fine. Provide something like getListView().getHeader().
I must be missing something simple here.I've searched around but don't think my search query is touching on the right topics to yield results. Anyhow, what I'm after is running through the array of data I bind to a ListView after a "Submit" button has been clicked.
View 3 Replies View RelatedI have a listview with a custom arrayadapter that handles about 15 strings. The style of each row alternates (between labels and values for those labels--for example row 1 could be "email address" and row 2 would be the actual email address). I'm changing the style of each row to alternate like this in the arrayadapter's getView() method. So if the item at the current position is a label, I'll change the styling from the default row style (which is what the values have applied to them). When the listview first loads, the styling is perfect and just how I want it to be. If I scroll the list slowly up or down, it stays that way. However, if I scroll the list fast up and down, the styling of the value rows starts changing to that of the label ones until all of the rows have the styling of a label row. I've used custom adapters on other listviews in the app with no problems like this. Found out that it also changes all of the rows to the label styling on portrait->landscape orientation changes. Doesn't do this on landscape->portrait changes. Below is the adapter I'm using.
public class DetailsAdapter extends ArrayAdapter<String> { private TextView text = null; private String item = null;
public DetailsAdapter(Context context, int resource, int textViewResourceId, String[] objects) { super(context, resource, textViewResourceId, objects);
} @Override public View getView(int position, View convertView, ViewGroup parent) { text = (TextView) super.getView(position, convertView, parent); item = getItem(position);
if (item.equals("Name") || item.equals("Mobile") || item.equals("Home") || item.equals("Email") || item.equals("Address")) { text.setBackgroundColor(0xFF575757); text.setTextSize(15);
text.setTypeface(null, Typeface.BOLD); text.setPadding(8, 5, 0, 5);
} else { text.setPadding(15, 15, 0, 15); } return text;
} @Override public boolean isEnabled(int position) { item = getItem(position);
if (item.equals("Name") || item.equals("Mobile") || item.equals("Home") || item.equals("Email") || item.equals("Address")) { return false;
} else { return true; } } }
I'm making a custom adapter so that I can display a list of items with icons which looks like the menu that comes up when you long click the home screen. For some reason though the list items are not clickable. The can be navigated to with the D-pad but they cannot be clicked in any way. I thought maybe the problem was with the AlertDialog I was using so I replaced a working adapter I had elsewhere but I have the same issue there. My adapter looks like this:
ArrayList<IconListItem> mItems; LayoutInflater mInflater;
public IconListAdapter(Context context, ArrayList<IconListItem> items) {
mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
mItems = items;
} public IconListAdapter(Context context) {
this(context, new ArrayList<IconListItem>());
} public void add(IconListItem item) { mItems.add(item);
notifyDataSetChanged(); return item;
} public void remove(IconListItem item) { mItems.remove(item); notifyDataSetChanged();
} @Override public int getCount() { return mItems.size();
} @Override public IconListItem getItem(int position) { return mItems.get(position);
} @Override public long getItemId(int position) { return position;
} @Override public View getView(int position, View convertView, ViewGroup parent) { View view;
if(convertView == null){ view = mInflater.inflate(R.layout.two_line_icon_list_item, null);
} else { view = convertView; } IconListItem item = mItems.get(position);
TextView lineOne = (TextView) view.findViewById(R.id.firstLine);
TextView lineTwo = (TextView) view.findViewById(R.id.secondLine);
ImageView iconImage = (ImageView) view.findViewById(R.id.icon);
lineOne.setVisibility(View.VISIBLE); lineTwo.setVisibility(View.VISIBLE);
iconImage.setVisibility(View.VISIBLE); lineOne.setText(item.getText());
if (item.getSubtext() == null) lineTwo.setVisibility(View.GONE);
else lineTwo.setText(item.getSubtext());
if (item.getIcon() == null) iconImage.setVisibility(View.GONE);
else iconImage.setImageDrawable(item.getIcon());
return view; }
And the XML it's inflating:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent" android:layout_height="fill_parent" android:padding="6dip" >
<ImageView android:id="@+id/icon" android:layout_width="wrap_content"
android:layout_height="fill_parent" android:layout_marginRight="6dip" />
<LinearLayout android:orientation="vertical" android:layout_width="wrap_content"
android:layout_weight="1" android:layout_height="fill_parent" >
<TextView android:layout_width="fill_parent" android:layout_height="wrap_content"
android:layout_weight="1"android:gravity="center_vertical"
android:id="@+id/firstLine" android:ellipsize="marquee" android:inputType="text" />
<TextView android:layout_width="wrap_content" android:layout_height="0dip"
android:layout_weight="1" android:ellipsize="marquee"
android:id="@+id/secondLine" android:inputType="text" />
</LinearLayout> </LinearLayout>
When I say they are not clickable, I mean that they items do not highlight in orange when I press them nor does onItemClick ever get called. In my code I have this, a different adapter for another purpose and it works perfectly
this.foos= foos; fa = new FooAdapter(this.foos); fooList.setAdapter(fa);
// View the details for an item when it is selected
fooList.setOnItemClickListener(new OnItemClickListener() {
@Override public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
Intent i = new Intent(MyActivity.this, MyOtherActivity.class);
i.putExtra("foo", ((fooAdapter)arg0.getAdapter()).getItem(arg2));
i.putExtra("list_position", arg2);
MyActivity.this.startActivityForResult(i, 0);
} } );
But when I swap out the first 3 lines for
IconListAdapter ila = new IconListAdapter(this);
ila.add(0, "Test 1", android.R.drawable.ic_menu_mylocation);
ila.add(0, "Test 2", android.R.drawable.ic_menu_edit);
ila.add(0, "Test 3", android.R.drawable.ic_menu_search);
groupList.setAdapter(ila);
I t stops working.
I have a list view that can display items based on internal state (it has items, and 'viewed' items). i need to be able to toggle between the two states, i do that using a simple button that change the adapter's state and the adapter then called notifyDatasetChanged(). My data DOES gets updated, however i was facing two problems:
if in the previous mode the list was partially scrolled, it stayed in that state after i changed the data set (if i was half the way down i'll be half way down in the new data set as well, this is not the behavior i want, but i cols not find a way to scroll the list manually to position 0. any ideas?
(setSelected is not exactly a solution since i DON'T want any selection i want to stay in touch mode) In my list View each item has an image that is fetched from the net, as so it's being brought using my networking manager and i send the image request ONLY if i'm in this screen for the first time OR if scroll state is idlle, i didn't want to start loading images from the getView method since if i fling the screen it may load a lot of unnecessary images. However when calling notifyDatasetChanged() the scroll listener methods are not called. i solved this one by using notifyDatasetInvalidated even though my data is not empty, is there a better way to solve this issue ?
I have a listView using a custom adapter. Each row contains a button and some other Views. I want to be able to click either on the button, or on the row itself (to edit the item of the list that is clicked).
Setting an onItemClickListener in the activity won't work because of this problem
I think I have to set an onClickListener in the getView() method of my adapter for it to work properly.
I would like to use my activity's onClickListener, in order to use a startActivityForResult() when the row is clicked, in order to have something returned to my activity when the item edition activity is over.
How can I do that?
I have a list view that can display items based on internal state (it has items, and 'viewed' items). i need to be able to toggle between by two states, i do that using a simple button that change the adapter's state and the adapter then called notifyDatasetChanged(). My data DOES gets updated,
However i was facing two problems:
1. if in the previous mode the list was partially scrolled, it stayed in that state after i changed the data set (if i was half the way down i'll be half way down in the new data set as well, this is not the behavior i want, but i cols not find a way to scroll the list manually to position 0. any ideas ?
2. In my list View each item has an image that is fetched from the net, as so it's being brought using my networking manager and i send the image request ONLY if i'm in this screen for the first time OR if scroll state is idlle, i didn't want to start loading images from the getView method since if i fling the screen it may load a lot of unnecessary images. However when calling notifyDatasetChanged() the scroll listener methods are not called. i solved this one by using notifyDatasetInvalidated even though my data is not empty, is there a better way to solve this issue ?
Just watched Google IO's "World Of ListView" presentation [1]. Awesome stuff. I think every Android dev should watch it.
One gotcha for me was to use BaseAdapter.notifyDataSetChanged[2]. I checked code that I have written more than a year ago and found that I did try to use that, but commented it out with '// doesn't work' and I use requery() instead. That is of course much slower.
I now tried to find out why I wrote that it didn't work and hoped that I am meanwhile so much wiser that it would be easier to understand the proper use of the API. So much for ambition: The effect I see is that the list is not updated after I call notifyDataSetChanged(), but works with requery() and I am not so much wiser.
What could be the issue here? I use a ResourceCursorAdapter and only implemented the bindView() Method. This method is called when I call notifyDataSetChanged() on the RCAdapter. However the method is called with a cursor that contains the stale data.
Now there was a second gotcha from the presentation that I couldn't really place. It was said that the data should be committed on the GUI thread too (before calling notifyDataSetChanged()). I couldn't place it then, but I now suspect that this may be the issue here. So the rule would be to do the commit() on the Cursor on the UI thread? I do the updates to the database using a Service. This Service runs in the background, sometimes the app is in the foreground at the same time, but most often not. So I don't see how I should commit something in a UI thread? Is this the issue here? There are two different Cursors and I could only use notifyDataSetChanged when it would be the same cursor, otherwise requery() is correct?
Is that it? Any ideas? Is somebody going to write a book "The Android SDK - The missing manual"?
I am using a ListView with an ArrayAdapter that holds objects. When I select an item, I am capturing the position and index of the selected item. If I scroll down prior to selection, the position and index represent the location of the item in the list. Selecting that items takes me to another activity. When I use the back button to return to the list, it seems that the ListView gets a new position and index for the visible items.
As a result, I can't figure out how to reference the selected item during the restart() of the ListView Activity. I have tried to capture position and index, but as I've said, they change upon returning to the Activity.
Is my understanding of the ListView "redraw" correct? Does it renumber my items based on what's visible? -When in the life cycle is getView() called? Is there a way to force an update to the ListView so that my captured index still points to the same object?
I was wondering if it is possible to start a ListActivity and in real time decide how far down the list it should be focused on. (Example: When the activity is started it checks for certain conditions and then it may scroll down to a row partially through the list.)
View 1 Replies View RelatedHow can I maintain the position of my ListView in my activity when I go to another activity (by launching another intent) and then come back (press the back button)?
View 2 Replies View RelatedI'm building a chat room application where new events are being polled for every X seconds. Every time that happens, this code updates the RoomAdapter (a custom subclass of ArrayAdapter) with the new data and scrolls it to the bottom:
RoomAdapter adapter = (RoomAdapter) getListAdapter();
for (int i=0; i<newEvents.size(); i++)
adapter.add(newEvents.get(i));
getListView().setSelection(events.size()-1);
This is fine, except that if the user is scrolling up to glance at the room's history, it's going to jump her down to the bottom when the poll happens. What I'd like to do is have it so that if the user is already at the bottom of the list, it stays there after a poll for new events. If the user's intentionally scrolled upwards, I'd like the user not to be disturbed.
How do I detect when I'm already scrolled to the bottom of a ListView?
Note: I can't do getListView().getSelectedItemPosition(), because as the docs note, calling setSelection when in touch mode does not actually select the item, just scrolls to it.
i've been trying to get this to work... but it isnt working.
there was no Exception to catch, the app just crash.
Code:
public class MainActivity extends Activity{
...
private void loadFromFile_populateListView(final String data){
[code].....
Im using ListView to to show some custom data, once data is updated in the adapter i call notifyDatasetChanged(), so the view will get updated, all of this works well, my issue though is i would like to run an animation once only on items that got changed when the adapter was updated. currently i keep a copy of all the changed objects and i tried to animate the correct items through the getView() call.
However if i do it only once for every getView call then i see no animation most of the time on items that changed. if i continue to do so in successive getView calls i see animation on items that don not change as well and also the ones that changed get animated again and again.
Im guessing sometimes android calls the getView() for other reasons than showing the generated view immediately, and thats the reason it doesnt work if i do it once.
I'd like to make a list adapter that formats views like this:
I want to be able to fire a different onClick when the user clicks the image. I have defined the onClick on the image itself in the getView() override, but how do I then get the position of the line that was clicked so I can update the record in the database to record the action?
I am aware of setSelection(), setSelectionFromTop(), and setSelectionAfterHeaderView(), but none of them seems to do what I want.
Given an item in the list, I want to scroll so that it is in view. If the item is above the visible window of the list, I want to scroll until the item is the first visible item in the list; if the item is below the visible window, I want it to scroll up until it is the last visible item in the list. If the item is already visible, I don't want any scrolling to occur. How do I go about this?
I have the following code to intantiate a SimpleCursorAdapter to use with a ListView. As you can see I have passed the R.layout.log_item to display the list items, and one value/control to bind to (TripDate).
SimpleCursorAdapter sca = new SimpleCursorAdapter(this, R.layout.log_item,c,new String[] {DBAdapter.KEY_LOG_TRIPDATE},new int[]{R.id.txtTripDate});
This works. I currently only have one widget in the layout xml, a TextView to hold the TripDate.
How do I pass multiple binding parameters for the additional widgets in the layout? So I can also display other info.
I have a ListView populated via a CursorAdapter. I give my user the ability to alter the data in the list. For example, the user can mark a row as being unread (the data are messages).
Suppose my user marked a row unread. Would a proper implementation mark the row in the database as read and then requery the Cursor?
I cant find a way to save the checkbox state when using a Cursor adapter. Everything else works fine but if i click on a checkbox it is repeated when it is recycled. Ive seen examples using array adapters but because of my lack of experience im finding it hard to translate it into using a cursor adapter. Could someone give me an example of how to go about it.code...
View 3 Replies View RelatedI have a ListView whose position should be changed automatically along with the data. So, when the adapter's data has changed (adapter is calling notifyDataSetInvalidated), I'm calling setSelection. This has no effect. If the call to setSelection is done later (e.g. in a click handler) it is working.
The second problem is, that the ListView maintains the scroll position of the list although the data is completely invalidated, that makes no sense IMO.
It looks like a call to layoutChildren before the call to setSelection does help in this case, but layoutChildren is protected.
What is the correct way to do this?
How to use a layout as empty view for a listview when the adapter has zero elements?
setEmptyView is not working with this code :
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Layouts used :
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main.xml
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I have seen examples implementing a custom Filter. The Android developer docs talk about implementing a Filterable interface. Does anyone have any advice and/or sample code on the best way to implement filtering in a ListView ?
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