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Android SparseBooleanArray ArrayIndexOutOfBounds

My app has an SparseBooleanArray to store selected entries in a ListAdapter.
The array is initialized as empty in the constructor.
private SparseBooleanArray mSelectedItemsIds;
public TaskArrayAdapter(#NonNull Context context, #NonNull List<Task> objects) {
super(context, R.layout.item_task, objects);
mSelectedItemsIds = new SparseBooleanArray();
Log.d("Booleansize", String.valueOf(mSelectedItemsIds.size()));
}
Now in the getView method I check, whether the current position is in the array or not:
if (mSelectedItemsIds.valueAt(position)) {
convertView.setBackgroundColor(Color.BLUE);
convertView.getBackground().setAlpha(100);
} else {
The mSelectedItemsIds is not altered during my testing. I am inserting entries to the list. After exactly 12 entries it crashes on mSelectedItemsIds.valueAt(position) with ArrayIndexOutOfBound at 11.
On another device it crashes after 14 inserts.
The size of the array is always 0 before every check.
How is that possible?
Here are all relevant parts of the adapter class (I cut out On Click listener, that are never triggered)
public class TaskArrayAdapter extends ArrayAdapter<Task> {
// Array with all selectedIds
private SparseBooleanArray mSelectedItemsIds;
public TaskArrayAdapter(#NonNull Context context, #NonNull List<Task> objects) {
super(context, R.layout.item_task, objects);
mSelectedItemsIds = new SparseBooleanArray();
Log.d("Booleansize", String.valueOf(mSelectedItemsIds.size()));
}/**
* Called for the ListView to get the view at position
* #param position
* #param convertView
* #param parent
* #return
*/
#NonNull
#Override
public View getView(final int position, #Nullable View convertView, #NonNull ViewGroup parent) {
// Get the data item for this position
final Task task = getItem(position);
// Check if an existing view is being reused, otherwise inflate the view
if (convertView == null) {
convertView = LayoutInflater.from(getContext()).inflate(R.layout.item_task, parent, false);
}
// Lookup view for data population
TextView tvDescription = (TextView) convertView.findViewById(R.id.tvDescription);
TextView tvDueDate = (TextView) convertView.findViewById(R.id.tvDueDate);
CheckBox cbDone = (CheckBox) convertView.findViewById(R.id.cbDone);
// Populate the data into the template view using the data object
tvDescription.setText(task.description);
if (task.dueDate != null) {
tvDueDate.setText(task.dueDate.toString());
} else {
tvDueDate.setText(R.string.no_due_date);
}
cbDone.setChecked(task.done);
cbDone.setTag(position);
convertView.setTag(position);
// Set listeners
cbDone.setOnClickListener(checkBoxListener);
convertView.setOnClickListener(viewClickListener);
convertView.setOnLongClickListener(viewLongClickListener);
Log.d("Booleansize", String.valueOf(mSelectedItemsIds.size()));
// check if the current item is selected for background color
if (mSelectedItemsIds.valueAt(position)) {
convertView.setBackgroundColor(Color.BLUE);
convertView.getBackground().setAlpha(100);
} else {
convertView.setBackgroundColor(Color.TRANSPARENT);
convertView.getBackground().setAlpha(255);
}
// Return the completed view to render on screen
return convertView;
}/**
* Change the isSelected value
* #param position
*/
public void toggleSelection(int position) {
selectView(position, !mSelectedItemsIds.get(position));
}
/**
* Completely forget the current selection
*/
public void removeSelection() {
mSelectedItemsIds = new SparseBooleanArray();
notifyDataSetChanged();
}
/**
* Set the select view to the given value
* #param position
* #param value
*/
public void selectView(int position, boolean value) {
if (value) {
mSelectedItemsIds.put(position, value);
} else {
mSelectedItemsIds.delete(position);
}
notifyDataSetChanged();
}
/**
* get number of selected entries
* #return
*/
public int getSelectedCount() {
return mSelectedItemsIds.size();
}
public SparseBooleanArray getSelectedIds() {
return mSelectedItemsIds;
}

You probably meant to use SparseBooleanArray.get method:
boolean get (int key)
Gets the boolean mapped from the specified key, or false if no such mapping has been made.
Use like so:
if (mSelectedItemsIds.get(position)) {
convertView.setBackgroundColor(Color.BLUE);
convertView.getBackground().setAlpha(100);
} else {
....
}
valueAt(int position) on the other hand takes position within the array, that's from 0 to size() - 1. You can use that to iterate over all values within the array.

Removing placeholder view from RecyclerView on notifyDataSetChanged?

I'm working on a project where I have a RecyclerView displaying items from a SQLiteDatabase. So I have build a custom adapter that uses a cursor instead of a list of data so I can update it straight from database queries. Additionally, I have a "placeholder" view that gets put into the recyclerView if the cursor is empty (no rows returned) that basically says "nothing here, add something by clicking +".
My issue is that when I add an item in that state (when the RecyclerView is initially empty) and call notifyDataSetChanged, the RecyclerView attempts to recycle the placeholder view instead of inflating the correct view item and I get a NullPointerException because I am attempting to update UI elements that were never initialized.
Here's what my adapter looks like now:
public class TextItemListAdapter extends RecyclerView.Adapter<TextItemListAdapter.ViewHolder> {
private List<TextItem> dataList;
private Cursor cursor;
private Context context;
private boolean empty = false;
private TextItemDataLayer dataLayer;
/**
* Constructor
* #param c Context
* #param curs The cursor over the data (Must be a cursor over the TextItems table)
*/
public TextItemListAdapter(Context c, Cursor curs) {
context = c;
dataLayer = new TextItemDataLayer(c);
dataLayer.openDB();
if (curs != null) {
switchCursor(curs);
}
empty = isEmpty(cursor);
}
/**
* ViewHolders populate the RecyclerView. Each item in the list is contained in a VewHolder.
*/
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
View parent;
TextItem textItem;
TextView location;
TextView text;
TextView time;
/**
* Create the viewholder for the item
* #param itemView the view contained in the viewHolder
*/
public ViewHolder(View itemView) {
super(itemView);
this.parent = itemView;
if (!empty) {
itemView.setClickable(true);
itemView.setOnClickListener(this);
}
location = (TextView) itemView.findViewById(R.id.textItem_item_title);
text = (TextView) itemView.findViewById(R.id.textItem_item_text);
time = (TextView) itemView.findViewById(R.id.textItem_item_time);
}
/**
* Handle a click event on an TextItem
* #param v
*/
#Override
public void onClick(View v) {
Intent i = new Intent(context, EditTextItemActivity.class);
i.putExtra("textItem", textItem);
context.startActivity(i);
}
}
/**
* Creation of the viewholder
* #param parent
* #param i
* #return
*/
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int i) {
View view;
if (empty) {
view = LayoutInflater.from(parent.getContext()).inflate(R.layout.text_item_list_item_empty, parent, false);
} else {
view = LayoutInflater.from(parent.getContext()).inflate(R.layout.text_item_list_item, parent, false);
}
ViewHolder vh = new ViewHolder(view);
return vh;
}
/**
* When the viewholder is bound to the recyclerview, initialize things here
* #param holder
* #param position
*/
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
if (!empty) {
if (!cursor.moveToPosition(position)) {
throw new IllegalStateException("couldn't move cursor to position " + position);
}
holder.textItem = dataLayer.buildTextItem(cursor);
holder.location.setText(holder.textItem.getLocation().getName());
holder.text.setText(holder.textItem.getMessage());
holder.time.setText(holder.textItem.getTime());
}
}
/**
* Get the number of items in the dataset
*
* If the dataset is empty, return 1 so we can imflate the "empty list" viewHolder
* #return
*/
#Override
public int getItemCount() {
if (empty) {
return 1;
}
return cursor.getCount();
}
/**
* switch the existing cursor with a new one
* #param c
*/
public void switchCursor(Cursor c) {
// helper method in TextItemDataLayer that compares two cursors' contents
if (TextItemDataLayer.cursorsEqual(cursor, c)) {
c.close();
return;
}
if (cursor != null) {
cursor.close();
}
cursor = c;
cursor.moveToFirst();
empty = isEmpty(cursor);
notifyDataSetChanged();
}
/**
* Check to see if the cursor is empty
*
* #param c the cursor to check
* #return
*/
private boolean isEmpty(Cursor c) {
return (c == null || c.getCount() == 0);
}
}
Some things I've tried that I haven't gotten to work:
notifyItemRemoved(0); if the list changes from empty to not empty
Changing switchCursor to compare the two cursors and call either notifyDataSetChanged() or notifyItemRemoved(0) like this
// helper method in TextItemDataLayer that compares two cursors' contents
if (OterDataLayer.cursorsEqual(cursor, c)) {
c.close();
return;
}
if (!isEmpty(c) && isEmpty(cursor)) {
empty = false;
notifyItemRemoved(0);
// or notifyDataSetChanged();
}
if (cursor != null) {
cursor.close();
}
cursor = c;
cursor.moveToFirst();
empty = isEmpty(cursor);
notifyDataSetChanged();
I've also considered having the empty placeholder view not be in the RecyclerView but instead be in the parent view to avoid the issue altogether, although I think it's better in terms of the overall structure of the app for it to be handled in the RecyclerView.

Your problem is simply in understanding how RecyclerView.Adapter works. Please have a look at this for clarification pertaining to your problem.
My issue is that when I add an item in that state (when the RecyclerView is initially empty) and call notifyDataSetChanged, the RecyclerView attempts to recycle the placeholder view instead of inflating the correct view item
Your are right about that, and it's happening because you did not override getItemViewType (int position), and the RecyclerView has no way to know that there are actually two different ViewHolder types or states.
I suggest following the above linked answer, refactor your code to provide two different ViewHolders, and then implement getItemViewType (int position). Something along these lines:
#Override
public int getItemViewType(int position) {
if(empty)
return EMPTY_VIEW_TYPE_CODE;
return REGULAR_VIEW_TYPE_CODE;
}

Getting position of View in onCreateViewHolder

I am using a RecyclerView with a single row layout with an ImageView and a TextView.
I want to implement a OnClickListener for the View and not for seperate ViewHolder objects. How can i get the position of the view in the Adapter?
Right now i'm deleting comments on click, but i cannot select the clicked View. I added a TODO in the appropriate line.
public class CommentAdapter extends RecyclerView.Adapter<CommentAdapter.ViewHolder> {
/** List of Comment objects */
private List<Comment> mCommentList;
/** Database with Comment objects */
private CommentsDataSource mDataSource;
/**
* Construcutor for CommentAdapter
*
* #param commentList List of Comment objects
* #param dataSource Database with Comment objects
*/
public CommentAdapter(List<Comment> commentList, CommentsDataSource dataSource) {
this.mCommentList = commentList;
this.mDataSource = dataSource;
}
/**
* Add Comment objects to RecyclerView
*
* #param position The position where the Comment object is added
* #param comment Comment Object
*/
public void add(int position, Comment comment) {
mCommentList.add(position, comment);
notifyItemInserted(position);
}
/**
* Remove Comment objects from RecyclerView
*
* #param comment Comment Object
*/
public void remove(Comment comment) {
int position = mCommentList.indexOf(comment);
// Avoid double tap remove
if (position != -1) {
mCommentList.remove(position);
mDataSource.deleteComment(comment);
notifyItemRemoved(position);
}
}
#Override
public ViewHolder onCreateViewHolder(final ViewGroup parent, int viewType) {
final View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.single_line_row, parent, false);
view.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO get position
remove(mCommentList.get(getItemCount() - 1));
}
});
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
final Comment comment = mCommentList.get(position);
holder.comment.setText(comment.getComment());
}
#Override
public int getItemCount() {
return mCommentList.size();
}
public static class ViewHolder extends RecyclerView.ViewHolder {
/** ImageView icon */
public ImageView icon;
/** TextView comment */
public TextView comment;
/**
* Constructor for ViewHolder
*
* #param itemView Layout for each row of RecyclerView
*/
public ViewHolder(final View itemView) {
super(itemView);
icon = (ImageView) itemView.findViewById(R.id.icon);
comment = (TextView) itemView.findViewById(R.id.comment);
}
}
}

You cannot use the position parameter of onBindViewHolder in a callback.
If a new item is added above, RecyclerView will not rebind your item so the position is obsolete.
Instead, RecyclerView provides a getAdapterPosition method on the ViewHolder.
#Override
public ViewHolder onCreateViewHolder(final ViewGroup parent, int viewType) {
final View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.single_line_row, parent, false);
final ViewHolder holder = new ViewHolder(view);
view.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
final int position = holder.getAdapterPosition();
if (position != RecyclerView.NO_POSITION) {
remove(mCommentList.get(position));
}
}
});
return holder;
}
I've added position != RecyclerView.NO_POSITION check because when item is removed, RecyclerView will fade out the View so it may still be clicked by the user but its adapter position will return NO_POSITION.

you can create a method to update position in your class.
in my case I need to attach watcher and get the position to update arraylist. here is the example:
class DodolWatcher bla bla {
private var position: Int = 0
fun updatePosition(pos:Int)
{
position = pos
}
override fun onTextChanged(charSequence: CharSequence, i: Int, i2: Int, i3: Int) {
Log.d("test", position.toString())
}
}
and in your onCreateViewHolder you can attach watcher to edittext
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RVPaymentMethodAdapter.ViewHolder {
....
bla bla
....
theWatcher = DodolWatcher() <-- this is the trick
amount.addTextChangedListener(theWatcher)
}
and you will able to update position in your bindViewHolder like this:
override fun onBindViewHolder(viewHolder: RVPaymentMethodAdapter.ViewHolder, position: Int) {
theWatcher.updatePosition(viewHolder.adapterPosition) <-- this is the trick
}

override getItemViewType method in your Adapter:
#Override
public int getItemViewType(int position) {
//...
return position;
}
Now viewType is position
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
int position=viewType; //position
//your code
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_recursive, parent, false);
return new ViewHolder(view);
}
for example
public class BrandBtnAdapter extends RecyclerView.Adapter<BrandBtnAdapter.MyViewHolder>
{
//............
#Override
public int getItemViewType(int position)
{
//...
return position;
}
#Override
public BrandBtnAdapter.MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType)
{
int position = viewType; //position
final View itemView = mInflater.inflate(mResource, parent, false);
return new BrandBtnAdapter.MyViewHolder(itemView);
}
}

Android -Stuck with ListView Item

I'm Developing an Android Application .In that Application ,I've set a list view each has One Imageview,Progressbar(InVisible) and two buttons .
plAdapter = new PlayAdapter();
lv1.setAdapter(plAdapter);
}
private static class AccessoriesViewHolder {
Button play,download;
ProgressBar pb;
}
private class PlayAdapter extends BaseAdapter {
#Override
public int getCount() {
return contactList.toArray().length;
}
#Override
public String getItem(int position) {
return a;
//return al[position];
}
#Override
public long getItemId(int position) {
return position;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
holder = null;
if (convertView == null) {
convertView = getLayoutInflater().inflate(R.layout.design, parent, false);
holder = new AccessoriesViewHolder();
holder.play = (Button) convertView.findViewById(R.id.btn_play);
holder.download = (Button) convertView.findViewById(R.id.btn_dwnld);
((Button) convertView.findViewById(R.id.btn_play)).setOnClickListener(mBuyButtonClickListener);
((Button) convertView.findViewById(R.id.btn_dwnld)).setOnClickListener(mBuyButtonClickListener);
((ProgressBar) convertView.findViewById(R.id.progress_bar)).setVisibility(View.INVISIBLE);
// convertView.setTag(holder);
} else
{
holder = (AccessoriesViewHolder) convertView.getTag();
}
/*
* The Android API provides the OnCheckedChangeListener interface
* and its onCheckedChanged(CompoundButton buttonView, boolean
* isChecked) method. Unfortunately, this implementation suffers
* from a big problem: you can't determine whether the checking
* state changed from code or because of a user action. As a result
* the only way we have is to prevent the CheckBox from callbacking
* our listener by temporary removing the listener.
*/
return convertView;
}
}
/**
* Quickly shows a message to the user using a {#link Toast}.
*
* #param message The message to show
*/
private void showMessage(String message) {
Toast.makeText(MainActivity.this, message, Toast.LENGTH_SHORT).show();
}
private OnClickListener mBuyButtonClickListener = new OnClickListener() {
#Override
public void onClick(View v) {
final int position = lv1.getPositionForView(v);
// int dummy=position;
showMessage(listsong[position].toString()+"");
((ProgressBar) convertView.findViewById(R.id.progress_bar)).setVisibility(View.INVISIBLE);
}
};
protected AdapterView<ListAdapter> getListView()
{
// TODO Auto-generated method stub
return null;
}
}
If I click one of the Button in a row ., the Progress bar Must be visible in that row.
The problem is, if i click a button the progress bar on other row gets visible but not corresponding row.

Just Add an OnClickListener for the button in the getView() method in your ListView Adapter and inside the OnClickListener set the visibility of the ProgressBar

Try to change your getView method like that:
#Override
public View getView(int position, View convertView, ViewGroup parent) {
holder = new AccessoriesViewHolder();
convertView = getLayoutInflater().inflate(R.layout.design, parent, false);
holder.play = (Button) convertView.findViewById(R.id.btn_play);
holder.download = (Button) convertView.findViewById(R.id.btn_dwnld);
((Button) convertView.findViewById(R.id.btn_play)).setOnClickListener(mBuyButtonClickListener);
((Button) convertView.findViewById(R.id.btn_dwnld)).setOnClickListener(mBuyButtonClickListener);
((ProgressBar) convertView.findViewById(R.id.progress_bar)).setVisibility(View.INVISIBLE);
return convertView;
}

android error unknown method 'getTitle'

Hello i'm testing the following code it's suppose to list all apps installed on an android powered machine.
To edit an compile it i use AIDE
an android java editor the problem is that AIDE always showing me an error: " unknown method 'getTitle'".
Someone can help me please?
public class AppListAdapter extends BaseAdapter {
private LayoutInflater mInflater;
private List<App> mApps;
public AppListAdapter(Context context) {
// cache the LayoutInflater to avoid asking for a new one each time
mInflater = LayoutInflater.from(context);
}
#Override
public int getCount() {
return mApps.size();
}
#Override
public Object getItem(int position) {
return mApps.get(position);
}
#Override
public long getItemId(int position) {
return position;
}
#Override
public View getView(int pos, View convertView, ViewGroup parent) {
AppViewHolder holder;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.row, null);
// creates a ViewHolder and stores a reference to the child view
holder = new AppViewHolder();
holder.mTitle = (TextView) convertView.findViewById(R.id.apptitle);
convertView.setTag(holder);
} else {
// reuse/overwrite the view passed assuming(!) that it is castable!
holder = (AppViewHolder) convertView.getTag();
}
holder.setTitle(mApps.get(pos).getTitle());
return convertView;
}
public void setListItems(List<App> list) {
mApps = list;
}
/**
* A view holder which is used to reuse views inside a list.
*/
public class AppViewHolder {
private TextView mTitle;
/**
* Sets the text to be shown as the app's title
*
* #param title the text to be shown inside the list row
*/
public void setTitle(String title) {
mTitle.setText(title);
}
}
}

You probably have no getTitle() method in your App class

mApps.get(pos)
returns you an object of type App
You would have to create a getTitle method in the App class.