Develop Reference

Changing ListView Item background bug

When I'm using parent.getChildAt(position).setBackgroundColor(Color.GRAY); in my public void onItemClick(AdapterView<?> parent, View view, int position, long id) it colorizes, but it works strange.
When I click first or second item it colorizes it... and every item away ~five records. Sometimes I've got NullPointerException. Completely weird, because position is unique and it should recieve me appropriate View, but it doesn't.
I saw solution with overriding getView method, but I'm using this adapter in different places. I just want to color clicked item. How to get reference to selected view?
EDIT:
In my adapter class I created:
public static int selectedItem = -1;
I added this to my overrided getView method:
if(selectedItem == position){
parent.getChildAt(position).setBackgroundColor(Color.GRAY);
}
In my activity I added that:
myAdapter.selectedItem = position;
myAdapter.notifyDataSetChanged();
And It doesn't work. Where I do a mistake?

It's not a bug - it's the way ListView re-uses the views to save resources.
So to avoid this behavior you should on every getView() set all used attributes for all your views.
Updated - to be quite clearIn your particular case it means that you should set color like this:
1) In onItemClick() - in your actitivity - you should remember given position as selected:
myAdapter.selectedItem = position
2) In getView() - in your adapter:
if(selectedItem == position)
parent.getChildAt(position).setBackgroundColor(Color.GRAY);
else
parent.getChildAt(position).setBackgroundColor(0);//or whatever defauld color
Update 2
If you want to select many items you should use some structure (like HashSet) to hold all the selected items:
1) In your activity class add member:
public static HashSet<Integer> mSelectedItems = new HashSet<Integer>();
2) In onItemClick() use following to flip selected state:
if(mSelectedItems.contains(position))
mSelectedItems.remove(position);
else
mSelectedItems.add(position);
3) In getView():
if(MainActivity.mSelectedItems.contains(position))
parent.getChildAt(position).setBackgroundColor(Color.GRAY);
else
parent.getChildAt(position).setBackgroundColor(0);//or whatever defauld color

At first read this article;
Then use ViewHolder pattern;
And try to setBackgroundColor() in onItemClick() like this:
view.setBackgroundColor(0);//or whatever defauld color

ListView Clicked Item Highlight not working properly

I have a ListView and have a onClickListener for this ListView.
ListView is using the SimpleAdapter, and populating the Data via a map.
Whenever Item is clicked, that List Item is getting highlighted.
But the problem is, Suppose I click the 4th Item on the List and scroll the list, then every 4th element is highlighted. I'm using a Selector xml to implement the highlight functionality
I know the problem is due to the screen refresh.
But how can I avoid this problem?
Searching for the answers from about a month now. I need a solution now.
Thanks in advance.
Selector.xml
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="#drawable/drawer_icon_normal" android:state_selected="false" android:state_pressed="false"/>
<item android:drawable="#drawable/drawer_icon_pressed" android:state_pressed="true"/>
<item android:drawable="#drawable/drawer_icon_activated" android:state_selected="true"/>
</selector>
Below is the code for populating the listView and onclick functionality.
//Note this code is not using the selector, how with this code also, functionality is same.
public void populateListView() {
//Populate the List View Here
//Set the adapter
SimpleAdapter flvadapter = new SimpleAdapter(getActivity(), finalSongList, android.R.layout.simple_list_item_1, new String[]{"filename"}, new int[]{android.R.id.text1});
fileListView.setAdapter(flvadapter);
fileListView.setBackgroundColor(Color.WHITE);
fileListView.setTextFilterEnabled(true);
fileListView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
//Registering the OnItemClicklistener
fileListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> arg0, View v, int position, long arg3) {
//TODO Auto-generated method stub
//fileListView.getItemAtPosition(position);
updateView(position);
index = position;
#SuppressWarnings("unchecked")
HashMap<String, String> hm = (HashMap<String, String>) fileListView.getItemAtPosition(position);
if (hm.get("fileuri") == null) {
AlertDialog.Builder adb = new AlertDialog.Builder(getActivity());
adb.setTitle("ListView OnClick");
adb.setMessage("Selected Item is = " + hm.get("fileuri"));
adb.setPositiveButton("Ok", null);
adb.show();
} else {
//Processing the Selected File
}
}
});
}
private void updateView(int index){
//View v=fileListView.getChildAt(index-fileListView.getFirstVisiblePosition());
selectedListViewItem=fileListView.getChildAt(index);
fileListView.setBackgroundColor(Color.WHITE);
if (selectedListViewItem != null) {
selectedListViewItem.setBackgroundColor(Color.CYAN);
}
}

In your updateView() function, you are changing the selectedListViewItem's background color. up to this point everything works like you would assume however when you scroll, every so ofter another row will already be "selected" even though you didn't do it yourself.
That is caused by view recycling, a function of Listview adapters that allow them to load faster by taking a row that has been scrolled out of the screen, fill it with new data and present it as is (without needing to inflate it from XML again.
Basically it will take your old blue row that is not on the screen anymore, put a new string in and display it as the new row.
The way you fix it is by implementing your own Adapter and overriding the getView method. there are a ton of resources that will show you how to do that. Here is one
One thing to keep in mind, once you implement your custom Adapter is that you will have to keep track of which items have been clicked so you can un-highlight and re-highlight items correctly.

you are changing the background color of the selected item but not reset it in the adapter
try to post your adapter code
so check in adapter getView method
if item is selected
setBackgroudColor for selected row
else
setBackgroundColor for normal row

How to cancel Android ListView item from being activated/highlighted in ListView's setOnItemClickListener?

In one of my Activities, I have multiple ListView controls. Say List 1, List 2 & List 3. On List 1 item's click, i load data for List 2 & List 3 from a webservice. And the clicked item's background is highlighted. I achieved this through following selector.
<item android:drawable="#drawable/item_pressed" android:state_pressed="true"/>
<item android:drawable="#drawable/item_focused" android:state_focused="false"
android:state_pressed="false"
android:state_selected="true"/>
<item android:state_activated="true" android:drawable="#drawable/item_selected"/>
As you can see, i have specified the android:state_activated="true" to change the BG of the clicked/tapped item. This works well.
Actually i want to prevent the clicked item from being selected/highlighted if data for some other item is being loaded ... like
list1.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// load data if no other call to web service is in progress
if (_isNotLoadingData) {
loadList2AndList3DataUsingWebService();
} else {
//Stop This Item From selected/highlighted
//BUT none of the following work. .. Item is always Selected
view.setSelected(false);
//view.setActivated(false);
//view.setEnabled(false);
}
}
});
Above code stops multiple calls to be directed to our web service but i am unable to stop the item from being highlighted/activated if the web service is not called for that ListView item.
How can i acieve this?
EDIT on 8:08 pm 19 Mar, 2012: No proper reply yet ... i am stuck & waiting for any help

I actually encountered the same issue a few days ago. The solution is not to set view.setItemChecked(false), but instead in the .onItemClick()-method, call your listview and set listview.setItemChecked(position, false). This solved it for me.
Example:
listView.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> adapterView, View view,
int position, long arg3) {
// load data if no other call to web service is in progress
if (_isNotLoadingData) {
loadList2AndList3DataUsingWebService();
} else {
ListView lv = (ListView) adapterView;
lv.setItemChecked(position, false);
}
}
});

Make the item in the adapter disabled. This will remove all clicks while you don't have to disable the item click listener or other such hacks.
I don't know how your adapter looks, but generally you override some methods in your adapter. Note that I call the method isLocked instead of isNotLocked. Using negative boolean values is generally a bad idea that causes confusion and in this case you won't even have to set it to false at the start since this is the default value for boolean.
public class MyCoolAdapter extends ListAdapter {
private boolean mIsLocked;
public boolean areAllItemsEnabled () {
return false;
}
public abstract boolean isEnabled (int position) {
if (mIsLocked) {
return false;
}
return true;
}
...
}
If you want to disable just certain rows you return false for those positions and true for others.
You will have to notify that dataset has changed when you change the isLoading parameter. This will cause the listview to requery the adapter.
For example:
public void setIsLoading(final boolean isLocked) {
mIsLocked = isLocked;
notifyDatasetChanged();
}

within the onclick listener you can call setonclicklistener(null) on the view that call the click event. That way view will remove its own onclicklistener.
mTitleView.setOnClickListener(null)

Try setting list selector to null using setSelector.

if you don't want to handle click event after first click, just use yourList.setOnItemClickListener(null)

listView.setOnItemClickListener(new OnItemClickListener()
{
#Override
public void onItemClick(AdapterView<?> adapterView, View view,
int position, long arg3)
{
//view.setEnabled(false);
//adapterView.setEnabled(false);
}
});
view.setEnabled(false); Use this if you want to disable the listItem which user has clicked.Thus prevents the onclick event on that particular item.
adapterView.setEnabled(false); Use this if you want to disable the entire listView.
It will prevent onclick event on entire listView.
Hope this help

How to highlight row in ListView in Android?

I need to highlight a row in a ListView that was selected (to show the user what he chose), so, it's not the one that is going to be chosen, it's the one he chose before.
I already have the location by:
ListView.setSelection(position);
And now what I want is to select this specific row and to highlight it.
The code of the onCreate() in the activity that contains the ListView:
public class CountryView extends Activity
{
protected static final String LOG_TAG = null;
/** Called when the activity is first created. */
String[] lv_arr = {};
ListAdapter adapter;
TextView t;
private ListView lvUsers;
private ArrayList<Coun> mListUsers;
String responce=null;
public int d;
int selectedListItem = -1;
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.country);
Intent data =getIntent();
mListUsers = getCoun();
lvUsers = (ListView) findViewById(R.id.counlistView);
lvUsers.setAdapter(new ListAdapter(this, R.id.counlistView, mListUsers));
selectedListItem=data.getExtras().getInt("PositionInList");
lvUsers.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
lvUsers.setOnItemClickListener(new OnItemClickListener()
{
int positionItem;
public void onItemClick(AdapterView<?> parent, View view,int position, long id)
{
Intent pongIntent = new Intent(getApplicationContext(),Trav.class);
int counId=mListUsers.get(position).id;
pongIntent.putExtra("response",mListUsers.get(position).p);
pongIntent.putExtra("responseCounID",counId);
//Put the position of the choose list inside extra
positionItem=position;
pongIntent.putExtra("PositionInListSet",positionItem);
setResult(Activity.RESULT_OK,pongIntent);
Log.i("CounID *******************************"," "+counId);
finish();
}
});
}
}

Since by default ListViews are set to a selection mode of NONE, in touch mode the setSelection method won't have visual effect.
For keeping the previous selection / visually display an explicit selection, first you must set your listview's choice mode appropriately:
listview.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
It's useful to read the API Docs of these methods:
setSelection
void android.widget.AdapterView.setSelection(int position)
Sets the currently selected item. To
support accessibility subclasses that
override this method must invoke the
overriden super method first.
Parameters:
position Index (starting at 0) of the data item to be selected.
setChoiceMode
void android.widget.ListView.setChoiceMode(int choiceMode)
Defines the choice behavior for the
List. By default, Lists do not have
any choice behavior
(CHOICE_MODE_NONE). By setting the
choiceMode to CHOICE_MODE_SINGLE, the
List allows up to one item to be in a
chosen state. By setting the
choiceMode to CHOICE_MODE_MULTIPLE,
the list allows any number of items to
be chosen.
Parameters: choiceMode One of CHOICE_MODE_NONE,
CHOICE_MODE_SINGLE, or CHOICE_MODE_MULTIPLE
In case this is not enough (say you'd like to always show the last selection differently beside the current selection), you should store your last selected item (a data which populates the ListAdapter) as lastSelectedItem, and in your adapter's getView method assign a different background resource to the renderer if it equals this lastSelectedItem.
If your last selection wouldn't refresh on selection change, you should explicitly call the notifyDataSetChanged method on your adapter instance.
Update
Since your activity containing the ListView is a child of an activity which waits for this one's result (based on the setResult(Activity.RESULT_OK,pongIntent); part), the initial idea is correct, the last position should be passed through the intent when starting the activity:
selectedListItem = getIntent().getIntExtra("PositionInList", -1);
lvUsers.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
lvUsers.setSelection(selectedListItem);
The ListView.CHOICE_MODE_SINGLE solution would work if you remain in the same activity, but you are finishing it on every itemClick (selection change), that's why the extra data should be passed to the starting Intent.
You can also set the previously selected item's background from your adapter -as mentioned above-, overriding its getView method:
lvUsers.setAdapter(new ArrayAdapter(this, R.id.counlistView, groups)
{
#Override
public View getView(int position, View convertView, ViewGroup parent)
{
final View renderer = super.getView(position, convertView, parent);
if (position == selectedListItem)
{
//TODO: set the proper selection color here:
renderer.setBackgroundResource(android.R.color.darker_gray);
}
return renderer;
}
});

Just:
Set the correct choice mode in your list view. setChoiceMode
Set a background to support the selection state in you item layout, like:
android:background="?android:attr/activatedBackgroundIndicator"
FYI:
http://developer.android.com/guide/topics/resources/drawable-resource.html#StateList
http://android-developers.blogspot.mx/2008/12/touch-mode.html

It's much easier to implement this in your layout files and let Android handle the rest...
1) Make sure you have android:choiceMode="" set on your ListView layout (singleChoice, multipleChoice, etc). By default it is set to none.
<ListView
android:id="#+id/invite_friends_fragment_contacts_list"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:choiceMode="multipleChoice"/> <!-- THIS LINE -->
2) Create a state selector XML file and save it in your drawables folder. In this example, we'll name it state_selector.xml:
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="#android:color/blue" android:state_selected="true"/>
<item android:drawable="#android:color/blue" android:state_activated="true"/>
<item android:drawable="#android:color/transparent"/>
</selector>
3) In your list item layout, add the state_selector.xml file as the background:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#drawable/state_selector"> <!-- THIS LINE -->
<!-- ALL OF YOUR ELEMENTS WILL GO HERE (TextViews, ImageViews, etc) -->
</RelativeLayout>
If you are using multipleChoice, you can override onItemClick()and set/unset selected items accordingly. Android will change the background color as specified in your state_selector.xml file.

I had a problem finding an easy solution to this because so many tutorials and answers contained information on single select via radio buttons (Which relied heavily on RadioGroup's).
My problem was that I could set the item to my "Highlighted" state but then couldn't reset the list when the next item was selected. Here is what I came up with:
listView.setOnItemClickListener(new ItemHighlighterListener ());
With this class:
private class ItemHighlighterListener implements OnItemClickListener{
private View lastSelectedView = null;
public void clearSelection()
{
if(lastSelectedView != null) lastSelectedView.setBackgroundColor(android.R.color.transparent);
}
#Override
public void onItemClick(AdapterView<?> arg0, View view, int arg2, long arg3) {
clearSelection();
lastSelectedView = view;
view.setBackgroundDrawable(view.getContext().getResources().getDrawable(R.drawable.shape_selected_menu_item));
}
}

I solve this problem in the following way:
1. set a lastClickId, when click the item in listView, update the lastClickId to position value, then update the view's background.
After this, when we click one item, this item will be highlighted, but when we scroll the listView(make the item which we selected out of the screen) and scroll back, the highlight is gone, because the method getView() rerun in your adapter, so, we have to do the next thing.
2. in your adapter, change the background in the method getView(), here is the code:
private static int lastClickId = -1;
private OnItemClickListener listener = new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
if ((lastClickId != -1) && (lastClickId != position)) {
parent.getChildAt(lastClickId).setBackgroundResource(
R.color.grey);
view.setBackgroundResource(R.color.blue);
}
if (lastClickId == -1) {
view.setBackgroundResource(R.color.blue);
}
lastClickId = position;
}
};
public static int getCurrentSelectedItemId() {
return lastClickId;
}
Adapter:
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
View view = mInflater.inflate(R.layout.tweet_list_layout, null);
// set selected item's background to blue
if (position == MainUserFeedFragment.getCurrentSelectedItemId()) {
view.setBackgroundResource(R.color.blue);
}
}

Why dont you store the selections in an array, then pass that array in the constructor of the ListView Array Adapter, something like myArrayAdapter(context,layoutID,dataArray,selectionArray)
then in your getView method for the arrayadapter, just do a check. For example in pseudocode
if row was previously selected
change background color

You can use transition. Follow my code because i have achieved highlighting of specific listview item by choice
Lets say you want to highlight first item for 5 seconds.
if(position == 0){
viewHolderThubnail.relImage.setBackgroundResource(R.drawable.translate);
TransitionDrawable transition = (TransitionDrawable) viewHolderThubnail.relImage.getBackground();
transition.startTransition(1000);
}else{
viewHolderThubnail.relImage.setBackgroundResource(R.color.white);
}
translate.xml
<?xml version="1.0" encoding="UTF-8"?>
<transition xmlns:android="http://schemas.android.com/apk/res/android">
<!-- The drawables used here can be solid colors, gradients, shapes, images, etc. -->
<item android:drawable="#drawable/new_state" />
<item android:drawable="#drawable/original_state" />
</transition>
new_state.xml
<?xml version="1.0" encoding="UTF-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<solid android:color="#92BCE7"/>
</shape>
original_state.xml
<?xml version="1.0" encoding="UTF-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<solid android:color="#FFFFFF"/>
</shape>
If you understood this code, which is very simple i must say, then the listview item at zero'th position will highlight in blue color for 5 seconds and then it will slow fade to white color.

The SIMPLEST of all
View updatedview=null;
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
//these two lines of code means that only one item can be selected at a time
if(updatedview != null)
updatedview.setBackgroundColor(Color.TRANSPARENT);
updatedview=view;
Toast.makeText(getApplicationContext(), " " + str[position],Toast.LENGTH_LONG).show();
view.setBackgroundColor(Color.CYAN);
}

Android ListView: get data index of visible item

I have an Android ListView created with a SimpleAdapter that has more items in it than fit in the screen. After the list has been scrolled, I need to get the position in the data model of the first visible item in the list.
Basically I want a function like: listView.getChildAt(0).getPositionInDataModel().
Adapter has a few functions in it, like getItemId(position) that looked useful; however, the SimpleAdapter implementation just returns the passed in position, not a row id like I'd hoped.
A brute force solution would be to get the View at index 0, and compare it to the view for each item in the adapter. However, there doesn't seem to be an easy way to get the view for a particular position from the adapter.
Anyone have any thoughts?

It's very easy. Just use ListView.getFirstVisiblePosition() + indexYouWant. For instance, to get the position in the adapter of the 2nd child displayed in the ListView, just use getFirstVisiblePosition() + 1.
No need for all the scary stuff shown in the reply above :)

listView.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener()
{
public void onItemSelected(AdapterView<?> parent,View view, int pos, long id)
{
AisleId= parent.getSelectedItemId();
}
#Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
}
});
In this we will get list item Id parent.getSelectedItemId();

Simply use the getPositionForView(View) (see documentation). The main advantage of this method is it also works with descendant Views of an item.