Develop Reference

Show only certain items in recycleview according to condition

I have a recycleview showing a list of audio files fetched from my audios.json file hosted on my server. i have a model class with a getter method getLanguage() to see the audio language. I would like to show only audio files of users preference in recycle view. Say for example, if user wants only english and russian i would like to show only list of russian and english. How can we achieve this? Right now the entire list is displayed.
public class AudioAdapter extends RecyclerView.Adapter<AudioAdapter.HomeDataHolder> {
int currentPlayingPosition = -1;
Context context;
ItemClickListener itemClickListener;
List<Output> wikiList;
public AudioAdapter(List<Output> wikiList, Context context) {
this.wikiList = wikiList;
this.context = context;
}
#NonNull
#Override
public HomeDataHolder onCreateViewHolder(#NonNull ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(context).inflate(R.layout.audio_row_layout,viewGroup,false);
HomeDataHolder mh = new HomeDataHolder(view);
return mh;
}
#Override
public void onBindViewHolder(#NonNull final HomeDataHolder homeDataHolder, int i) {
String desc = wikiList.get(i).getLanguage() + " • " + wikiList.get(i).getType();
homeDataHolder.tvTitle.setText(wikiList.get(i).getTitle());
homeDataHolder.tvotherinfo.setText(desc);
homeDataHolder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if (itemClickListener != null)
itemClickListener.onClick(view,homeDataHolder.getAdapterPosition());
}
});
homeDataHolder.rippleLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if (itemClickListener != null)
itemClickListener.onClick(view,homeDataHolder.getAdapterPosition());
}
});
}
#Override
public int getItemCount() {
return wikiList.size();
}
#Override
public long getItemId(int position) {
return position;
}
#Override
public int getItemViewType(int position) {
return position;
}
public void setClickListener(ItemClickListener itemClickListener) { // Method for setting clicklistner interface
this.itemClickListener = itemClickListener;
}
public class HomeDataHolder extends RecyclerView.ViewHolder {
TextView tvTitle,tvotherinfo;
MaterialRippleLayout rippleLayout;
public HomeDataHolder(View v) {
super(v);
this.tvTitle = v.findViewById(R.id.title);
this.tvotherinfo = v.findViewById(R.id.audioDesc);
this.rippleLayout = v.findViewById(R.id.ripple);
}
}
}

The general idea for this should be:
you have one list with all items
you have filter rules selected by the user
You filter items from number 1, to see which ones match the constraints and store this in another list.
Then the recycler view only shows the items of the list from number 3.
This means that recycler view's getItemCount would return the size of the filtered list, not the whole list.

Instead of passing the wikiList as it is, filter it then send it:
Lets say that you filled up the wikiList, before passing it to the adapter, filter it like this:
In the activity that you initialize the adapter in:
public class YourActivity extends ............{
........
........
//your filled list
private List<Output> wikiList;
//filtered list
private List<Output> filteredList= new ArrayList<Output>();
//filters
private List<String> filters = new ArrayList<String>();
//lets say the user chooses the languages "english" and "russian" after a button click or anything (you can add as many as you want)
filters.add("english");
filters.add("russian");
//now filter the original list
for(int i = 0 ; i<wikiList.size() ; i++){
Output item = wikiList.get(i);
if(filters.contains(item.getLanguage())){
filteredList.add(item);
}
}
//now create your adapter and pass the filteredList instead of the wikiList
AudioAdapter adapter = new AudioAdapter(filteredList , this);
//set the adapter to your recyclerview........
......
.....
......
}
I use above "english" and "russian" for language. I don't know how they are set in your response, maybe you use "en" for "english" so be careful.

Multiply recycler view and adapters

Actually I am going to ask more than one question here. Don't ban me, please, just read a full story. Let's begin. So I need to create an activity or fragment (it doesn't matter) with to parts (views) inside (top and bottom). Inside the bottom part dynamically loads buttons (sometimes 2, sometimes 30), there is a click listener on them. When a user clicks on a button, the button appears on the top part (view) and disappears on the bottom view. The buttons on the top view also have click listener and if a user clicks on a button it appears on the bottom view and disappears on a top. So this is a task. I thought how to implement it. The simplest solution that I created is: two views are recycler views with two adapters. Mm, probably it is not the best solution, I am pretty sure of it. I could implement two adapters, but I can't implement the click listener for my second adapter. It doesn't work!? I don't like this way for two reasons: 1. both adapters are the same; 2. I can't use click adapter for second adapter. Below you can find my code.
My adapter - standard adapter:
public class KeyboardAdapter extends RecyclerView.Adapter<KeyboardAdapter.KeyboardAdapterViewHolder> {
private List<String> values;
/*
* An on-click handler that we've defined to make it easy for an Activity to interface with
* our RecyclerView
*/
private final KeyboardAdapterOnClickHandler mClickHandler;
/**
* The interface that receives onClick messages.
*/
public interface KeyboardAdapterOnClickHandler {
void onClick(int position, String nameClicked);
}
/**
* Creates a SourceAdapter.
*
* #param clickHandler The on-click handler for this adapter. This single handler is called
* when an item is clicked.
*/
public KeyboardAdapter(List<String> myDataset, KeyboardAdapterOnClickHandler clickHandler) {
values = myDataset;
mClickHandler = clickHandler;
}
/**
* Cache of the children views for a forecast list item.
*/
public class KeyboardAdapterViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
// each data item is just a string in this case
private Button btnValue;
private String mName;
public View layout;
private int parentId;
private KeyboardAdapterViewHolder(View view) {
super(view);
//layout = view;
btnValue = view.findViewById(R.id.btn);
//parentId = ((View) btnValue.getParent()).getId();
// Call setOnClickListener on the view passed into the constructor (use 'this' as the OnClickListener)
view.setOnClickListener(this);
}
public void setData(String name) {
mName = name;
btnValue.setText(mName);
}
#Override
public void onClick(View view) {
int adapterPosition = getAdapterPosition();
mClickHandler.onClick(adapterPosition, mName);
}
}
#Override
public long getItemId(int position) {
return super.getItemId(position);
}
#Override
#NonNull
public KeyboardAdapterViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_layout, parent, false);
return new KeyboardAdapterViewHolder(v);
}
#Override
public void onBindViewHolder(#NonNull KeyboardAdapterViewHolder viewHolder, final int position) {
viewHolder.setData(values.get(position));
}
#Override
public int getItemCount() {
return values.size();
}
#Override
public int getItemViewType(int position) {
return 0;
}
public void remove(int position) {
values.remove(position);
notifyItemRemoved(position);
notifyItemRangeChanged(position, values.size());
}
}
MainActivity:
protected void onCreate(Bundle savedInstanceState) {
...
String s = "test it";
mAdapter = new KeyboardAdapter(virtualKeyboardInit(s), MainActivity.this);
recyclerView1.setAdapter(mAdapter);
// empty list just to init rv
answerList = new ArrayList<>();
mAdapter1 = new KeyboardAdapter1(answerList, MainActivity.this); // doesn't work, error message "KeyboardAdapter1.KeyboardAdapterOnClickHandler cannot be applied to MainActivity"
recyclerView2.setAdapter(mAdapter1);
}
private List<String> virtualKeyboardInit(String s) {
boolean checkBool = true;
// convert string to array and then to list
String [] strArray = s.split("(?!^)");
stringList = new ArrayList<>(Arrays.asList(strArray));
// shuffle letters in the list
long seed = System.nanoTime();
Collections.shuffle(stringList, new Random(seed));
// API 24
// /String[] strArray = Stream.of(cArray).toArray(String[]::new);
return stringList;
}
#Override
public void onClick(int position, String nameClicked) {
mAdapter.remove(position);
}
These are just a fragment of code. So, what can I do in this case? Thank you for attention and help.

Working with Long Click Listener with recycler-android

i am working on a notapad like android app project. i which i have implemented recycler.
My project contains NotedAdaper class that extends RecyclerView.Adapter<NotesAdapter.ViewHolder>
in that class using the below code i used click listener,
public class NotesAdapter extends RecyclerView.Adapter<NotesAdapter.ViewHolder> {
private List<Notes> mNotes;
private Context mContext;
public NotesAdapter(Context context, List<Notes> notes) {
mNotes = notes;
mContext = context;
}
#Override
public NotesAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
Context context = parent.getContext();
LayoutInflater inflater = LayoutInflater.from(context);
// Inflate the custom layout
View notesView = inflater.inflate(R.layout.items_notes, parent, false);
// Return a new holder instance
ViewHolder viewHolder = new ViewHolder(notesView);
return viewHolder;
}
// Easy access to the context object in the recyclerview
private Context getContext() {
return mContext;
}
#Override
public void onBindViewHolder(NotesAdapter.ViewHolder viewHolder, final int position) {
// Get the data model based on position
Notes notes = mNotes.get(position);
// Set item views based on your views and data model
TextView textView = viewHolder.preTitle;
textView.setText(notes.getTitle());
TextView textView1 = viewHolder.preText;
textView1.setText(notes.getText());
String color=notes.getColor();
CardView preCard=viewHolder.preCard;
preCard.setBackgroundColor(Color.parseColor(color));
ImageView img = viewHolder.preImage;
img.setVisibility(View.GONE);
viewHolder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Notes notes = mNotes.get(position);
Intent intent = new Intent(view.getContext(),EditNote.class);
Bundle bundle = new Bundle();
bundle.putSerializable("DATA",notes);
intent.putExtras(bundle);
getContext().startActivity(intent);
Toast.makeText(getContext(), "Recycle Click" + position+" ", Toast.LENGTH_SHORT).show();
}
});
}
// Returns the total count of items in the list
#Override
public int getItemCount() {
return mNotes.size();
}
public static class ViewHolder extends RecyclerView.ViewHolder {
// Your holder should contain a member variable
// for any view that will be set as you render a row
public RobotoTextView preTitle, preText;
public ImageView preImage;
public CardView preCard;
public ViewHolder(View itemView) {
super(itemView);
preTitle = (RobotoTextView) itemView.findViewById(R.id.preTitle);
preText = (RobotoTextView) itemView.findViewById(R.id.preText);
preImage=(ImageView) itemView.findViewById(R.id.preImage);
preCard=(CardView) itemView.findViewById(R.id.preCard);
}
}}
And its absolutely working find. on clicking of a item in recycler, it retrieves the data using position of that item. and showing in another activity.
just like, suppose a activity shows the list of notes created by user. and clicking on any note, it shows the full content of that note.
but now i want to implement Long click listener on the item. and get the position.
so that, i used the following code ...
viewHolder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
#Override
public boolean onLongClick(View view) {
Notes notes = mNotes.get(position);
Toast.makeText(getContext(), "long Click" + position+" ", Toast.LENGTH_SHORT).show();
return false;
}
});
so, its also working.
but what i want is, on long click, it should only show that Toast.
but its not only showing the long click toast. but also recognising click listener and after showing the toast>> "Long click: ..." it executing the the code written for single click event.
n i dont want it.
both listeners should work separately.
but why its executing single click after long click??? any idea???
Am i making mistake anywhere?

So, the following changes in my code, help me to achieve my output.
1) The method onBindViewHolder is called every time when you bind your view with data. So there is not the best place to set click listener. You don't have to set OnClickListener many times for the one View. Thats why, i wrote click listeners in ViewHolder, (actually that was not my question, but i read somewhere that it would be the best practice, thats why i am following it)
like this,
public static class ViewHolder extends RecyclerView.ViewHolder {
// Your holder should contain a member variable
// for any view that will be set as you render a row
public ImageView preImage;
public CardView preCard;
// We also create a constructor that accepts the entire item row
// and does the view lookups to find each subview
public ViewHolder(final View itemView) {
// Stores the itemView in a public final member variable that can be used
// to access the context from any ViewHolder instance.
super(itemView);
itemView.findViewById(R.id.preTitle);
preImage=(ImageView) itemView.findViewById(R.id.preImage);
preCard=(CardView) itemView.findViewById(R.id.preCard);
itemView.setOnLongClickListener(new View.OnLongClickListener() {
#Override
public boolean onLongClick(View view) {
int p=getLayoutPosition();
System.out.println("LongClick: "+p);
return true;// returning true instead of false, works for me
}
});
itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
int p=getLayoutPosition();
Notes notes = mNotes.get(p);
Toast.makeText(getContext(), "Recycle Click" + p +" ", Toast.LENGTH_SHORT).show();
}
});
}
}
You may notice that, in onLongClick, i have returned "true", bydefault it was "false".
and this change works for me.

just make onLongClick(View v) returns return true instead of return false
this solved my problem it should solve yours too

i think you should set both the listeners from ViewHolder class.
itemView.setOnClickListener(...);
itemView.setOnLongClickListener(...);
And call getAdapterPosition() from ViewHolder to get the adapter position of the item.
You can checkout the following resource.
https://www.bignerdranch.com/blog/recyclerview-part-1-fundamentals-for-listview-experts/

I think this is an easier way to implement onClick and longClickListeners to RecyclerViews. Here's my code snippet. I've cut out unnecessary codes from here.
public class PrescriptionAdapter extends RecyclerView.Adapter<PrescriptionAdapter.ViewHolder> {
static final String TAG = "RecyclerViewAdapterMedicineFrequency";
ArrayList<Prescription> pdata;
Context context;
OnItemClickListener onItemClickListener;
OnItemLongClickListener onItemLongClickListener;
public PrescriptionAdapter(Context context, ArrayList<Prescription> presData, OnItemClickListener onItemClickListener, OnItemLongClickListener onItemLongClickListener) {
this.pdata = presData;
this.context = context;
this.onItemClickListener = onItemClickListener;
this.onItemLongClickListener = onItemLongClickListener;
}
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener, View.OnLongClickListener {
TextView pName, totalMeds;
ImageView pImage;
OnItemClickListener onItemClickListener;
OnItemLongClickListener onItemLongClickListener;
public ViewHolder(View itemView, OnItemClickListener onItemClickListener, OnItemLongClickListener onItemLongClickListener) {
super(itemView);
pName = (TextView) itemView.findViewById(R.id.prescriptionName);
totalMeds = (TextView) itemView.findViewById(R.id.totalMeds);
pImage = (ImageView) itemView.findViewById(R.id.prescriptionImage);
this.onItemClickListener = onItemClickListener;
this.onItemLongClickListener = onItemLongClickListener;
itemView.setOnClickListener(this);
itemView.setOnLongClickListener(this);
}
#Override
public void onClick(View v) {
onItemClickListener.onItemClick(getAdapterPosition());
}
#Override
public boolean onLongClick(View v) {
onItemLongClickListener.onItemLongClick(getAdapterPosition());
return true;
}
}
public interface OnItemClickListener {
void onItemClick(int i);
}
public interface OnItemLongClickListener {
void onItemLongClick(int i);
}
}

How to detect change in listview from mainactivity

Summary: I need a way to trigger my calculate() function within my main activity when an item is added or removed from my ListView
Background:
My android application fills a listview with list items. A list item contains a textview and an imagebutton (delete) that removes the item from the list on click. I use a custom adapter to keep track of changes in the list. This all works fine.
In my main acticity, some calculations take place based on the values in the list in a function called calulate(). I want to call this function whenever an item is added or deleted from the list. However, I don't know if this is possible and how to implement such a function.
I noticed that it is possible to add an observer using registerDataSetObserver() that will be notified when notifyDataSetChanged() is called. However, I'm not sure if this is what I need and how to implement this. Any help or suggestions are more than welcome.
Here is my CustomListAdapter:
public class CustomListAdapter extends BaseAdapter {
static final String TAG = "CustomListAdapter";
private Context context;
ArrayList <String> listArray;
LayoutInflater inflater;
public CustomListAdapter(Context context, List <String> inputArray) {
super();
this.context = context;
this.listArray = (ArrayList<String>) inputArray;
}
#Override
public int getCount() {
return listArray.size(); // total number of elements in the list
}
#Override
public String getItem(int i) {
return listArray.get(i); // single item in the list
}
#Override
public long getItemId(int i) {
return i; // index number
}
#Override
public View getView(int position, View convertView, final ViewGroup parent) {
View V = convertView;
if(V == null) {
LayoutInflater vi = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
V = vi.inflate(R.layout.selected_drug_list_item, null);
}
//place text in textview
String listItem = listArray.get(position);
TextView textView = (TextView) V.findViewById(R.id.selectedDrugName);
textView.setText(listItem);
ImageButton deleteSelectedDrugButton = (ImageButton) V.findViewById(R.id.deleteSelectedDrugButton);
deleteSelectedDrugButton.setTag(position);
//Listener for the delete button. Deletes item from list.
deleteSelectedDrugButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View view) {
//re
Integer index = (Integer) view.getTag();
listArray.remove(index.intValue());
notifyDataSetChanged();
}
});
return V;
}
public void add(String input) {
listArray.add(input);
notifyDataSetChanged();
Log.v(TAG, input + " added to list");
}
public void remove(String input){
listArray.remove(input);
notifyDataSetChanged();
Log.v(TAG, input + " added to list");
}
}
Here is how my ListView is initialized in my onCreate() method.
selectionListView = (ListView) findViewById(R.id.selectionListView);
selectionAdapter = new CustomListAdapter(this,myListItems);
selectionListView.setAdapter(selectionAdapter);
If any other code fragment is required, I'll happily provide it.

You may create Interfece that will be implemented by Your Main Activity and passed to Adapter (eg. in constructor)
public interface SomeInterface
{
public void foo();
}
Add SomeInterface object in Your Adapter
SomeInterface responder=null;
public CustomListAdapter(Context context, List <String> inputArray, SomeInterface responder) {
super();
this.context = context;
this.listArray = (ArrayList<String>) inputArray;
this.responder=responder;
}
public void add(String input) {
listArray.add(input);
notifyDataSetChanged();
Log.v(TAG, input + " added to list");
responder.foo();
}
public void remove(String input){
listArray.remove(input);
notifyDataSetChanged();
Log.v(TAG, input + " added to list");
responder.foo();
}
and implements SomeInterface in Your MainActivity
public class MainActivity extends Activity implements SomeInterface
{
...
public void foo()
{
//do whatever
}
private initializeAdapter()
{
CustomListAdapter adapter=new Adapter(this, someArray, this);
}
}

You can create a callback interface with a simple method, like stuffHappened(). Then, let your activity implement that interface. Now you can add a constructor argument which has as type the callback interface, pass the activity in, keep it as a member variable on the adapter and call the stuffHappened() method whenever you need to send feedback to your activity.

Android: Select ListView Item in onResume

I have an Activity that hosts multiple fragments using the actionbar's tab functionality. One of those fragments contains a ListView. Upon this tab being selected, I'd like to select a certain item.
To do this programmatically, I use the following code (where calls is the ListView)
private void selectItem(int position)
{
long itemId = calls.GetItemIdAtPosition(position);
calls.PerformItemClick(calls, position, itemId);
}
If this ListView has been rendered, and I'm calling this, no problem. However, if I call it from onResume, then the code executes but nothing is selected in the end. I figure this is because at the point where I'm calling selectItem, not all items of the ListView have been rendered yet. If however I start off a background thread, sleep for a couple hundred milliseconds, then run the same code (in the ui thread of course), everything is fine, but this is an ugly hack.
Now you might be wondering, "why isn't he using calls.setSelection"? The thing is, I'm using a custom layout that performs expansion - so I need to actually click on the item I want selected (which in turn triggers the layout expansion for the item selected). However, I can call the code that is performed on PerformItemClick directly, the results will be the same (the layout expansion isn't performed).
Isn't there any way for me to catch the "Listview has finished rendering all viewable items" point in time, and then execute my selectItem call at that point? In ASP.NET, I have an event on every UI item telling me when it is done rendering, so I do item selection at that point but I haven't found anything.
Regards
Stephan
Here's the Adapter I'm using
public class ActiveCallsAdapter: ObservableAdapter<Call>
{
public ActiveCallsAdapter(Activity activity, ObservableCollection<Call> calls)
: base(activity, calls)
{
}
public override View GetView(int position, View convertView, ViewGroup parent)
{
var item = items[position];
var view = (convertView ?? context.LayoutInflater.Inflate(Resource.Layout.Call, parent, false)) as LinearLayout;
//View view = convertView;
//if (view == null) // no view to re-use, create new
// view = context.LayoutInflater.Inflate(Resource.Layout.Call, null);
SetTextView(view, Resource.Id.CallerName, item.CallerName);
SetTextView(view, Resource.Id.CallerNumber, item.CallerNumber);
SetTextView(view, Resource.Id.CallStatus, item.State.ToString());
SetTextView(view, Resource.Id.CallDuration, item.Duration);
return view;
}
public void Update(LinearLayout view, Call item)
{
SetTextView(view, Resource.Id.CallerName, item.CallerName);
SetTextView(view, Resource.Id.CallerNumber, item.CallerNumber);
string identifier = "callState_" + item.State.ToString();
int resourceId = Application.Context.Resources.GetIdentifier(identifier, "string", Application.Context.PackageName);
string callStateString = item.State.ToString();
if (resourceId != 0)
{
try
{
callStateString = Application.Context.Resources.GetString(resourceId);
}
catch (Exception e)
{
AndroidLogModel.Model.AddLogMessage("ActiveCallsAdapter", "Unable to find call state string with resource id " + resourceId + " state string: " + identifier, 3);
}
}
SetTextView(view, Resource.Id.CallStatus, callStateString);
//SetTextView(view, Resource.Id.CallDuration, item.Duration);
}
public void UpdateDuration(LinearLayout view, Call item)
{
SetTextView(view, Resource.Id.CallDuration, item.Duration);
}
}
And the base class of that adapter
public class ObservableAdapter<T>: BaseAdapter<T>
{
protected readonly Activity context;
protected readonly ObservableCollection<T> items;
public ObservableAdapter(Activity context, ObservableCollection<T> collection)
{
this.context = context;
this.items = collection;
//this.collection.CollectionChanged += new System.Collections.Specialized.NotifyCollectionChangedEventHandler(collection_CollectionChanged);
this.items.CollectionChanged += (sender, e) => NotifyDataSetChanged();
}
void collection_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
{
NotifyDataSetChanged();
}
public override T this[int position]
{
get { return items[position]; }
}
public override int Count
{
get { return items.Count; }
}
public override long GetItemId(int position)
{
return position;
}
public override View GetView(int position, View convertView, ViewGroup parent)
{
var item = items[position];
var view = (convertView ?? context.LayoutInflater.Inflate(Resource.Layout.Call, parent, false)) as LinearLayout;
// configure view here
return view;
}
protected void SetTextView(LinearLayout view, int id, string text)
{
var textView = view.FindViewById<TextView>(id);
if (textView != null)
textView.SetText(text, TextView.BufferType.Normal);
}
}

My Mono skills are limited so I don't know if I fully understood your adapter, anyway I've adapted some old code and made an adapter that expands a single item when click, also it will move the ListView in onResume to a desired position:
private static class CustomAdapter extends BaseAdapter {
// the data
private ArrayList<String> mData;
// an int pointing to a position that has an expanded layout,
// for simplicity I assume that you expand only one item(otherwise use
// an array or list)
private int mExpandedPosition = -1; // -1 meaning no expanded item
private LayoutInflater mInflater;
public CustomAdapter(Context context, ArrayList<String> items) {
mInflater = LayoutInflater.from(context);
mData = items;
}
public void setExpandedPosition(int position) {
// if the position equals mExpandedPosition then we have a click on
// the same row so simply toggle the row to be gone again
if (position == mExpandedPosition) {
mExpandedPosition = -1;
} else {
// else change position of the row that was expanded
mExpandedPosition = position;
}
// notify the adapter
notifyDataSetChanged();
}
#Override
public int getCount() {
return mData.size();
}
#Override
public String getItem(int position) {
return mData.get(position);
}
#Override
public long getItemId(int position) {
return position;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if (convertView == null) {
convertView = mInflater.inflate(R.layout.ad_expandedelement,
parent, false);
}
((TextView) convertView.findViewById(R.id.textView1))
.setText(getItem(position));
// see if there is an expanded position and if we are at that
// position
if (mExpandedPosition != -1 && mExpandedPosition == position) {
// if yes simply expand the layout
convertView.findViewById(R.id.button1).setVisibility(
View.VISIBLE);
} else {
// this is required, we must revert any possible changes
// otherwise the recycling mechanism will hurt us
convertView.findViewById(R.id.button1).setVisibility(View.GONE);
}
return convertView;
}
}
The onListItemClick will simply be:
#Override
protected void onListItemClick(ListView l, View v, int position, long id) {
// set the expanded(or collapsed if it's a click on the same row that
// was previously expanded) row in the adapter
((CustomAdapter) getListView().getAdapter())
.setExpandedPosition(position);
}
and in onResume will have:
#Override
protected void onResume() {
super.onResume();
// set the position to the desired element
((CustomAdapter) getListView().getAdapter()).setExpandedPosition(15);
// set the selection to that element so we can actually see it
// this isn't required but has the advantage that it will move the
// ListView to the desired
// position if not visible
getListView().setSelection(15);
}
The R.layout.ad_expandedelement is a simple vertical LinearLayout with a TextView and an initially hidden(visibility set to gone) Button. For this Button I change the visibility to simulate expanding/collapsing a row in the ListView. You should be able to understand my code, if you want I can post on github the full sample.

While I'm not sure of the exact equivalent in C#/Mono, the Android framework provides a callback on Activity called onWindowFocusChanged() that indicates the period when the Window associated with a given Activity is visible to the user. You may have better luck waiting to call your selection method until that time, as the ListView should be measured and laid out by that point. In Java, it would be something like this:
#Override
public void onWindowFocusChanged (boolean hasFocus) {
if (hasFocus) {
selectItem(position);
}
}
You may need to have a bit more logic in there, this callback is directly associated with window focus and isn't a true lifecycle method. I can get called multiple times if you are displaying Dialogs or doing other similar operations.