I have problem with deleting item's from ArrayList
and synchronising Adapter
.
I have my RecyclerView
adapter with some ArrayList
inside it called items
. I download some list from the server and dispaly inside it. Whenever I click on some of list items I would like to delete it from server, from local ArrayList and notify the adapter about it. The problem is that when I delete everything from down
to up
from the list everything is ok, but when f.e. I delete 1st element from the list and then randomly some of the elements it deletes element after the one I clicked. In some cases the app crashes (f.e. I delete 1st element then the last one). The error I get is f.e.:
java.lang.IndexOutOfBoundsException: Invalid index 4, size is 4
Look like it's something with list size but i don't know what is wrong?
Here is the function where I got position from (setPopUpListener(popupMenu, position)
):
// Binding New View
@Override
public void onBindViewHolder(ViewHolder holder, final int position) {
RecipeItem item = items.get(position);
// Binding Recipe Image
Picasso.with(context).load(item.getImgThumbnailLink()).into(holder.recipeItemImage);
// Binding Recipe Title
holder.recipeItemTitle.setText(item.getTitle());
// Binding Recipe Subtitle
String subtitle = "Kuchnia " + item.getKitchenType() + ", " + item.getMealType();
holder.recipeItemSubtitle.setText(subtitle);
// Binding Recipe Likes Count
holder.recipeItemLikesCount.setText(Integer.toString(item.getLikeCount()));
// Binding Recipe Add Date
holder.recipeItemAddDate.setText(item.getAddDate());
// Binding Recipe Options Icon
holder.recipeItemOptionsIcon.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
PopupMenu popupMenu = new PopupMenu(context, v);
setPopUpListener(popupMenu, position); // Setting Popup Listener
inflatePopupMenu(popupMenu); // Inflating Correct Menu
popupMenu.show();
}
});
// Item Click Listener
holder.setClickListener(new RecipeItemClickListener() {
@Override
public void onClick(View view, int position) {
// taking to recipe activity
}
});
}
Here is setPopUpListener()
- just look at removeFromFavourites(position)
:
// Setting Popup Listener
private void setPopUpListener(PopupMenu popupMenu, final int position) {
popupMenu.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
@Override
public boolean onMenuItemClick(MenuItem item) {
switch (popupType) {
// Add To Favourites Menu
case 0: {
switch (item.getItemId()) {
case R.id.item_add: {
addToFavourites(position);
return true;
}
}
}
// Remove From Favourites Menu
case 1: {
switch (item.getItemId()) {
case R.id.item_remove: {
removeFromFavourites(position);
return true;
}
}
}
}
return false;
}
});
}
Here is where the error appears (removeFromFavourites(position)
):
// Removing User's Favourite
private void removeFromFavourites(int position) {
// Checking Connection Status
if (!FormValidation.isOnline(context)) {
showSnackbarInfo(context.getString(R.string.err_msg_connection_problem),
R.color.snackbar_error_msg);
} else {
SQLiteHandler db = new SQLiteHandler(context);
// Getting User Unique ID
String userUniqueId = db.getUserUniqueId();
db.close();
RecipeItem listItem = items.get(position);
// Getting Recipe Unique ID
String recipeUniqueId = listItem.getUniqueId();
// Removing From User's Favourites
removeFromUserFavouritesOnServer(recipeUniqueId, userUniqueId);
// Removing Item From Local Array List
items.remove(position);
// Notifying Adapter That Item Has Been Removed
notifyItemRemoved(position);
}
}
SOLUTION - HOPE THIS WILL HELP SOMEBODY
I have found the soution for this. If somebody will ever try to dynamicly remove elements from his array list and notifyItemRemoved(position)
do not send clicked position as a parameter inside onBindViewHolder(ViewHolder holder, int position)
. You will meet with exactly the same situation as I did.
If you have 4 displayed elements in a list f.e. [0, 1, 2, 3]
and try to remove from the end of the list everything will be fine cause clicked positions
will match exactly the same positions in ArrayList
. For example if you click 4th element:
position = 3
- position you will get when clicked on list element; myArray.remove(position)
- will remove element with index = 3
and notifyItemRemoved(position)
- will animate the list and remove deleted element from the displayed list. You are going to have following list: [0, 1, 2]
. This is fine.
Situation changes when you want to delete random element. Let's say I want to delete 3rd displayed list element. I click on it to delete so i get:
position = 2
-> myArray.remove(position)
-> notifyItemRemoved(position)
In this case the ArrayList I am going to get will be like this: [0, 1, 3]
. In I now click on the last dispalyed element and would like to delete it that's what I will get:
position = 3
->myArray.remove(position)
-> notifyItemRemoved(position)
But what happens? App suddenly crashes with exception: java.lang.IndexOutOfBoundsException: Invalid index 3, size is 3
. It means that we are trying to get element at the position that does not exist. But why? I got my clicked position from element... This is what happened:
At the beggining we had:
ARRAY LIST INDEXES -> [0, 1, 2, 3]
POSITIONS FROM CLICK -> [0, 1, 2, 3]
After Deleting 3rd element:
ARRAY LIST INDEXES -> [0, 1, 2]
POSITIONS FROM CLICK -> [0, 1, 3]
Now when I try to delete element at position = 3
we can't do that. We do not have that position. The max position we can get is 2
. Thats why we get the exception. How to manage that problem?
In onBindViewHolder(ViewHolder holder, int position)
we used position
in
removeFromFavourites(position)
. But we also have our returned holder
. If we use method called: getAdapterPosition()
from class RecyclerView.ViewHolder
we are at home.
getAdapterPosition
From developer site: http://developer.android.com/reference/android/support/v7/widget/RecyclerView.ViewHolder.html#getAdapterPosition()
This will always return index identical to that in ArrayList
. So summaring all we had to do was changing position
parameter with holder.getAdapterPosition()
:
// Binding New View
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
RecipeItem item = items.get(position);
// Binding Recipe Image
Picasso.with(context).load(item.getImgThumbnailLink()).into(holder.recipeItemImage);
// Binding Recipe Title
holder.recipeItemTitle.setText(item.getTitle());
// Binding Recipe Subtitle
String subtitle = "Kuchnia " + item.getKitchenType() + ", " + item.getMealType();
holder.recipeItemSubtitle.setText(subtitle);
// Binding Recipe Likes Count
holder.recipeItemLikesCount.setText(Integer.toString(item.getLikeCount()));
// Binding Recipe Add Date
holder.recipeItemAddDate.setText(item.getAddDate());
// Binding Recipe Options Icon
holder.recipeItemOptionsIcon.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
PopupMenu popupMenu = new PopupMenu(context, v);
setPopUpListener(popupMenu, holder.getAdapterPosition()); // Setting Popup Listener
inflatePopupMenu(popupMenu); // Inflating Correct Menu
popupMenu.show();
}
});
// Item Click Listener
holder.setClickListener(new RecipeItemClickListener() {
@Override
public void onClick(View view, int position) {
// taking to recipe activity
}
});
}
Use
notifyItemRangeChanged(position, getItemCount());
after
notifyItemRemoved(position);
You don't need to use index, just use position.
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