Develop Reference

How to highlight a item in recycler view by position android

I am working on an application where I need a spinner if the user chooses some values from the spinner then I need to smooth scroll for that particular position and highlight the item of that position . I have done something for that I have a method that will highlight the position if the view is visible if the view is not visible it will not highlight. So, I am facing some issues like this.
This is the place where I get the position from the spinner
versesSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
final int possition = (int) versesSpinner.getSelectedItemId();
recyclerView.smoothScrollToPosition(possition);
setBackgroundColor(possition);
}
#Override
public void onNothingSelected(AdapterView<?> adapterView) {
}
});
And this is the method where I highlight the item
public void setBackgroundColor(int position) {
for (int i = 0; i < versesList.size(); i++) {
View view = mLayoutManager.findViewByPosition(i);
try {
if (view != null) {
if (i == position)
view.setBackgroundColor(Color.parseColor("#504cbee7"));
else
view.setBackgroundColor(Color.WHITE);
}
} catch (Exception e) {}
}
}
Here the problem is while calling the setBackground() method before the smooth scroll method reaches that particular item.
The highlighting will be done only if the view is visible and if the view is not null.
Please tell me if there is any other way is there to achieve this else please tell me how can I find out if the smooth scroll to position has reached the particular item
I hope it make sense.

You are trying to change the background of item before it has completed the scrolling. Use a handler to schedule that task after some time.
recyclerView.postDelayed(new Runnable(){
public void run(){
setBackgroundColor(possition);
}
},1000);

You might consider having a loom at my answer here to check how to highlight the items in your RecyclerView on demand. Now if you want a smooth scroll to the position highlighted just add smoothScrollToPosition(position) right after calling the notifyDataSetChanged() function.
So the highLightTheListItems() function might look like this which I'm referring from my answer there.
public void highLightTheListItems() {
// Modify your list items.
// Call notifyDataSetChanged in your adapter
yourAdapter.notifyDataSetChanged();
// Now smooth scroll to the position you want.
}
Hope that helps.

ListeView recycling Views causing problems

When I click a list item, every 12th item is also selected. ListViews recycle views and therefore many items are being selected, any idea how I overcome the problem so just the items I click are marked as checked.
#Override
public void onListItemClick(ListView l, View v, int position, long id){
CheckedTextView check = (CheckedTextView) v;
if (check.isChecked()){
check.setChecked(false);
selections.remove((Integer) position);
}
else{
check.setChecked(true);
selections.add((Integer) position);
}
}
I use an ArrayAdapter. Names is a String[] of about 1000 options.
adapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_multiple_choice, names);
setListAdapter(adapter);

As this answer CheckBox in ListView says maintain a list of your checked items and then check your CheckBox in getView based on that list.
Also set the onCheckedChangeListener for that CheckBox null before checking it or else the corresponding listener will be called.

In lisview, recycling is very tricky concept, first by recycled view android means view which were used earlier, so basically this view will contain all the parameter which you or user set earlier.
This view is now returned to your adapter, what you do is to check if its null inflate a new view set new values supply it back, if its not then refresh the widgets view contains with new values and then supply it back.
Now coming back to your code, you are simply checking if this view was checked or not, say suppose you checked first view in you list, now when you scroll down further this same view will be returned to you through recycling and guess what it will be checked again, remember it was the same first view you used, this is reason for your problem for founding a unchecked view checked.
Now to your resolution, maintain a separate list somewhere globally to hold on checked index, and from your adapter just check or uncheck the checkbox before sending it to list depending about its index presence in maintained list. this will resolve your probelm.
Please try something like this.
-- Have a static HashMap on your main activity.
--Implement two methods over you activity, AddSelection and RemoveSelection
--On your adapter, implement onCheckedStateChanged listener and, perform either addition or deletion from the map, based on position in list.
In Your Activity:
private static HashMap<Integer,Integer> selectedPositions = new HashMap<Integer,Integer>();
public static boolean isSelected(int position){
System.out.println("#### Position: " + position + " Value: " + selectedPositions.containsKey(position));
return selectedPositions.containsKey(position);
}
public static void addSelection(int position){
System.out.println("#### Puttin Position: " + position);
selectedPositions.put(position,position);
}
public static void removeSelection(int position){
System.out.println("#### Removing Position: " + position);
selectedPositions.remove(position);
}
In your adapter:
checkbox.setChecked(MainActivity.isSelected(position));
checkbox.setOnCheckedChangeListener(new OnCheckedChangeListener(){
#Override
public void onCheckedChanged(CompoundButton view, boolean state) {
// TODO Auto-generated method stub
if(state == true){
MainActivity.addSelection(position);
}else{
MainActivity.removeSelection(position);
}
}
});
thats it now, whenever you want iterate through the hasmap for finding out selected items, make sure you clear it when job is done, else u will end up piling selected positions again and again.

listview getting new instance when swiping the listview

I have one listview in my application,it contains two rows one for task and another one for alarm,date,severity. Initially first row of the list item only displayed for all list item and the second one is invisible. When i click the list item the second row displayed for that item as well as click another list item at that time the above list item closed that second row. Its working fine for me...My problem is if i open one list item and then swipe the listview at then i click the another list item at that time the above one cannot be closed because the above list item instance will be chnaged.please any one help me how to solve this problem...
int lastselectedPosition == -1
#Override
public void onItemClick(AdapterView<?> arg0, View view, int position,
long id) {
TextView textviewDate=(TextView)view.findViewById(R.id.taskTimeidDaytoDay);
selectedtaskDate=textviewDate.getText().toString().trim();
if (lastselectedPosition == -1) {
Log.i(TAG,"Loopif:"+lastselectedPosition);
TextView twTaskTime = (TextView) view
.findViewById(R.id.taskTimeidDaytoDay);
TextView twSeverity = (TextView) view
.findViewById(R.id.severityidDaytoDay);
TextView twAlarm = (TextView) view
.findViewById(R.id.alarmidDaytoDay);
twAlarm.setVisibility(view.VISIBLE);
twSeverity.setVisibility(view.VISIBLE);
twTaskTime.setVisibility(view.VISIBLE);
lastselectedPosition = position;
lastSelectedItem = arg0.getChildAt(position);
} else {
// Log.i(TAG,"LoopElse:"+lastselectedPosition);
lastSelectedItem.findViewById(R.id.taskTimeidDaytoDay)
.setVisibility(lastSelectedItem.GONE);
lastSelectedItem.findViewById(R.id.severityidDaytoDay)
.setVisibility(lastSelectedItem.GONE);
lastSelectedItem.findViewById(R.id.alarmidDaytoDay).setVisibility(
lastSelectedItem.GONE);
if (lastselectedPosition != position) {
view.findViewById(R.id.taskTimeidDaytoDay).setVisibility(
view.VISIBLE);
view.findViewById(R.id.severityidDaytoDay).setVisibility(
view.VISIBLE);
view.findViewById(R.id.alarmidDaytoDay).setVisibility(
view.VISIBLE);
lastselectedPosition = position;
lastSelectedItem = arg0.getChildAt(position);
} else {
lastselectedPosition = -1;
lastSelectedItem = null;
}
}
GetView():
#Override
public View getView(int position, View view, ViewGroup parent) {
Log.i("XXXX", "Inside getView");
final DaytoDayTaskGetterSetter objDaytoDaygetset=getItem(position);
TextView textviewTask;
TextView txtviewAlarm ,txtviewTaskTime ,txtviewSeverity;
Log.i(TAG,"InsideGetView:"+position);
LayoutInflater inflater=(LayoutInflater)context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
if(view==null)
{
view=inflater.inflate(R.layout.daytodaylistlayout,null);
}
Log.i("XXXX", "before first test");
textviewTask=(TextView)view.findViewById(R.id.tasknameidDaytoDay);
txtviewAlarm=(TextView)view.findViewById(R.id.alarmidDaytoDay);
txtviewSeverity=(TextView)view.findViewById(R.id.severityidDaytoDay);
txtviewTaskTime=(TextView)view.findViewById(R.id.taskTimeidDaytoDay);
return view;
}
In first i click the "gdfgdtet" list item it show another row and then i click the second list item "dfgsdgsd" at that time the above list item "gdfgdtet" closed the second row.This is a normal output.Suppose if i open the "gdfgdtet" list item and then swipe the listview at that time both of "gdfgdtet" "dfgsdgsd" will be opened and crashed...because the above one list item reference changed when i am swiping please how to solve this problem...

I'll try to provide you a good answer that explains why you are having this problems, but the general idea is that you have to see this video - http://www.youtube.com/watch?v=wDBM6wVEO70
please take my words kindly - you don't seems to understand what ListView + BaseAdapter recycling mechanism is all about, and I strongly recommend you see the full video I linked you to, and read more about that.
in general, the specific problem in your code is that you are holding reference to listview item (lastSelectedItem), then trying to use it latter assuming it's still representing same list item. that's wrong. in that stage (after scrolling) the view already been recycled to represent another item in the list (based on the adapter implementation).
listView's number of childs is not the size of adapter.getCount()!!!!!!!!
listViews's number of childs = number of visible list items on screen + 1 + headers + footers
let's say you have the 5 first items visible on screen, then you are scrolling down. when you see the 7 item you actually see the same view instance that used to show the first list item and been recycled.
getView will call in this stage with convertView != null and position in the adapter to let you reuse the item by putting new values such different text/image to the same instance
this mechanism provides ability to display list of "infinite" number of items in the list, and holding in memory only a few number of views. imagine that you have list of 5000 items in the list, and each one of them have different view instance - you would get outOfMemory exception in a sec!
complete explanation about that would be hard to write in stackoverflow answer's context.
it just too long trying to explain one of the most important and complex UI components in android, but this links would be a good start:
http://www.youtube.com/watch?v=wDBM6wVEO70
How ListView's recycling mechanism works
http://mobile.cs.fsu.edu/the-nuance-of-android-listview-recycling-for-n00bs/
if you are interstead in "quick" fix for your specific problem, the solution would be:
hold in the data structure represents your list item additional field indicating if it in "close" or "open state. when item been clicked - change the data accordinly and call notifyDatasetChanged(). inside the getView() check if item is open or close and populate it accordinly
by the way - it's not only "quick fix" solution, but also the right thing to do anyway

You should pay attention to Tal Kanel's answer and consider this one to be an extension to it. His advice will help you in the long run.
Add a boolean field to DaytoDayTaskGetterSetter class:
public class DaytoDayTaskGetterSetter {
....
....
boolean open;
public DaytoDayTaskGetterSetter (.., .., boolean o) {
....
....
open = o;
}
....
....
public boolean shouldOpen() {
return open;
}
public void setOpen(boolean o) {
open = o;
}
}
In your getView(), check if the object has its open value set:
DaytoDayTaskGetterSetter obj = (DaytoDayTaskGetterSetter) getItem(position);
if (obj.shouldOpen()) {
// Set visibility to true for the items
} else {
// Set visibility to false for the items
}
On list item click, traverse the list and set open for all list items to false. Use the position to retrieve DaytoDayTaskGetterSetter and set its open to true:
#Override
public void onItemClick(AdapterView<?> arg0, View view, int position, long id) {
for (DaytoDayTaskGetterSetter obj : listContainingObjects) {
obj.setOpen(false);
}
DaytoDayTaskGetterSetter clickedItem = (DaytoDayTaskGetterSetter)
yourAdapter.getItem(position);
clickedItem.setOpen(true);
yourAdapter.notifyDataSetChanged();
}
Edit 1:
#Override
public void onItemClick(AdapterView<?> arg0, View view, int position, long id) {
DaytoDayTaskGetterSetter clickedItem = (DaytoDayTaskGetterSetter)
yourAdapter.getItem(position);
if (clickedItem.shouldOpen()) {
clickedItem.setOpen(false);
} else {
for (DaytoDayTaskGetterSetter obj : listContainingObjects) {
obj.setOpen(false);
}
clickedItem.setOpen(true);
}
yourAdapter.notifyDataSetChanged();
}

How to change other items in a Android ListView when one item is clicked

I have a ListView that contains items with checkboxes that should behave sometimes like a CHOICE_MODE_MULTIPLE and sometimes like a CHOICE_MODE_SINGLE. What I mean is for certain items in the list, when selected certain other items needs to be deselected whilst other can remain selected.
So when item A is checked I can find in my data the item B that needs to be unchecked but how do I get the UI to refresh to show this as I (I believe) cannot find the actual View that represents B but just it's data?

It sounds like you're off to a good start. You're right that you should be manipulating the underlying data source for item B when A is clicked.
Two tips that may help you:
Your getView() method in the Adapter should be looking at your data source and changing convertView based on what it finds. You cannot find the actual View that represents B because in a ListView, the Views are recycled and get reused as different data needs to be displayed. Basically, when an item is scrolled off the list, the View that was used gets passed to the getView() function as convertView, ready to handle the next element's data. For this reason, you should probably never directly change a View in a ListView based on user input, but rather the underlying data.
You can call notifyDataSetChanged() from within your adapter to signal that somewhere the underlying data has been changed and getView() should be called again for the elements currently displayed in your list.
If you're still having trouble, feel free to post some code that illustrates the specific problem that you're having. It's much easier to provide concrete advice when the problem is better defined. Hope this helps!

you can use singleChoice alartDialog, i have used like:
private int i = 0; // this is global
private final CharSequence[] items = {"Breakfast", "Lunch", "Dinner"}; // this is global
Button settings = (Button)view.findViewById(R.id.settings);
settings.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(final View v) {
AlertDialog.Builder builder = new AlertDialog.Builder(v.getContext());
//Title of Popup
builder.setTitle("Settings");
builder.setSingleChoiceItems(items, i,
new DialogInterface.OnClickListener() {
// When you click the radio button
public void onClick(DialogInterface dialog, int item){
i=item;
}
});
builder.setPositiveButton("Confirm",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int item) {
if (i == 0) {
//it means 1st item is checked, so do your code
}
if (i == 1) {
//it means 2nd item is checked, so do your code
} /// for more item do if statement
}
});
//When you click Cancel, Leaves PopUp.
builder.setNegativeButton("Cancel", null);
builder.create().show();
}
});
i have initialized i=0, so that for the very first time when user click on settings button, the first item is selected. and after then when user select other item, i have saved the i value so that next time when user click settings button, i can show user his/her previously selected item is selected.

I come across and solve this question today.
public class ItemChooceActivity extends Activity implements OnItemClickListener {
private int chosenOne = -1;
class Madapter extends BaseAdapter {
.....
.....
#Override
public View getView(final int position, View convertView,
ViewGroup parent) {
// TODO Auto-generated method stub
if (chosenOne != position) {
set the view in A style
} else {
set the view in B style
}
return convertView;
}
}
#Override
public void onItemClick(AdapterView<?> arg0, View view, int position,
long arg3) {
,,,,
chosenOne = position;
adapter.notifyDataSetChanged();
,,,
}
}

How to avoid having android spinner call itemselectedlistener when setting adapter?

It appears that android's Spinner class (and possibly ListView in general, although I don't know for sure) calls your OnItemSelectedListener's onItemSelected() method after you call setAdapter(), even if the user hasn't explicitly selected anything yet.
I can see how this would be useful in many situations, but there are times when I only want onItemSelected() to be called when an item is actually specifically selected.
Is there a way to control this behaviour and have Spinner NOT call onItemSelected() after setting the adapter?

I haven't used this solution for very long yet so I'm not totally confident that it works as expected, but I've had luck so far with this workaround:
spinner.setOnItemSelectedListener( new OnItemSelectedListener() {
protected Adapter initializedAdapter = null;
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
// Always ignore the initial selection performed after setAdapter
if( initializedAdapter !=parent.getAdapter() ) {
initializedAdapter = parent.getAdapter();
return;
}
...
}
}
Is there a better way?

Add listener to spinner like below:
spinner.post(new Runnable(){
public void run()
{
spinner.setOnItemSelectedListener( new OnItemSelectedListener() {
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
...
}
}
}
});

I've used the setTag and getTag methods, and created a resource id called "spinnerstate".
Then whenever I programmatically set the adapter, I set the "spinnerstate" tag to "init", and in the fired event, set it to "ready" and ignore the event. (note my code is Mono for Android se it will look different):
Set Adapter:
profileSpn.SetTag (Resource.Id.spinnerstate, "init");
profileSpn.Adapter = new ArrayAdapter (this, Android.Resource.Layout.SimpleSpinnerItem, items.ToArray ());
Item Selected event:
string state = (string)((Spinner)sender).GetTag (Resource.Id.spinnerstate);
if (state == "init") {
((Spinner)sender).SetTag (Resource.Id.spinnerstate, "ready");
return;
}
I agree that this is not desired behaviour in almost 100% of cases, and I don't think it's good design on the part of Google, but there you go.

I did similar things before, I used count value. Using parent adapter object is incomplete because it can be a problem when view is refreshed or getView() called again.
Therefore, I recommend that using array of counter.
At first, define array of count in adapter globally.
private int isInitializedView[];
And then initialize it on getView().
isInitializedView[position] = 0;
In the selection listener, do something that you want if it already initialized.
holder.mySpinner.setOnItemSelectedListener(new OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) {
isInitializedView[position]++;
if(isInitializedView[position] > 1) {
// do someting that you want
}
}
#Override
public void onNothingSelected(AdapterView<?> parentView) {}
});
(Note that isInitializedView[position]++; can be come after if() routine, and only trigger event when this value is >0 . It's your choice.)

I had three spinner in my activity and all spinner adapter data has been filled at runtime(from web-service data after call from onCreate method). So it automatically call onItemSelected(AdapterView<?> parent, View view, int position, long id) method of spinner.
I solved this issue by using onUserInteraction() method of activity
check this method that user is interacting with spinner or not. if yes then perform the action else not
Declare isUserIntract boolean variable globally
in onItemSelected method use following procedure
If(isUserIntract)
{
//perform Action
}
else{
//not perform action
}
use below code in activity
#Override
public void onUserInteraction() {
super.onUserInteraction();
isUserIntract = true;
}