问题
I'm trying to refresh specific item in RecyclerView.
Story: Whenever user clicks on item, it shows AlertDialog. User can type some text by clicking ok button. I want to show this text in this item and show invisible ImageView - declared in XML and adapter ViewHolder -
I used this function in AlertDialog Positive Button to update the item:
private void updateListItem(int position) {
View view = layoutManager.findViewByPosition(position);
ImageView medicineSelected = (ImageView) view.findViewById(R.id.medicine_selected);
medicineSelected.setVisibility(View.VISIBLE);
TextView orderQuantity = (TextView) view.findViewById(R.id.order_quantity);
orderQuantity.setVisibility(View.VISIBLE);
orderQuantity.setText(quantity + " packet added!");
medicinesArrayAdapter.notifyItemChanged(position);
}
But this code not only changes the itemView at passed position, but also changes some of other itemView(s) as well!
How should I change specific itemView correctly by clicking on it?
回答1:
You can use the notifyItemChanged(int position) method from the RecyclerView.Adapter class. From the documentation:
Notify any registered observers that the item at position has changed. Equivalent to calling notifyItemChanged(position, null);.
This is an item change event, not a structural change event. It indicates that any reflection of the data at position is out of date and should be updated. The item at position retains the same identity.
As you already have the position, it should work for you.
回答2:
Update single item
- Update the data item
- Notify the adapter of the change with
notifyItemChanged(updateIndex)
Example
Change the "Sheep" item so that it says "I like sheep."
String newValue = "I like sheep.";
int updateIndex = 3;
data.set(updateIndex, newValue);
adapter.notifyItemChanged(updateIndex);
My full answer with more examples is here.
回答3:
I think I have an Idea on how to deal with this. Updating is the same as deleting and replacing at the exact position. So I first remove the item from that position using the code below:
public void removeItem(int position){
mData.remove(position);
notifyItemRemoved(position);
notifyItemRangeChanged(position, mData.size());
}
and then I would add the item at that particular position as shown below:
public void addItem(int position, Landscape landscape){
mData.add(position, landscape);
notifyItemInserted(position);
notifyItemRangeChanged(position, mData.size());
}
I'm trying to implement this now. I would give you a feedback when I'm through!
回答4:
I got to solve this issue by catching the position of the item that needed to be modified and then in the adapter call
public void refreshBlockOverlay(int position) {
notifyItemChanged(position);
}
, this will call onBindViewHolder(ViewHolder holder, int position) for this specific item at this specific position.
回答5:
Add the changed text to your model data list
mdata.get(position).setSuborderStatusId("5");
mdata.get(position).setSuborderStatus("cancelled");
notifyItemChanged(position);
回答6:
In your adapter class, in onBindViewHolder method, set ViewHolder to setIsRecyclable(false) as in below code.
@Override
public void onBindViewHolder(RecyclerViewAdapter.ViewHolder p1, int p2)
{
// TODO: Implement this method
p1.setIsRecyclable(false);
// Then your other codes
}
回答7:
A way that has worked for me personally, is using the recyclerview's adapter methods to deal with changes in it's items.
It would go in a way similar to this, create a method in your custom recycler's view somewhat like this:
public void modifyItem(final int position, final Model model) {
mainModel.set(position, model);
notifyItemChanged(position);
}
回答8:
Below solution worked for me:
On a RecyclerView item, user will click a button but another view like TextView will update without directly notifying adapter:
I found a good solution for this without using notifyDataSetChanged() method, this method reloads all data of recyclerView so if you have image or video inside item then they will reload and user experience will not good:
Here is an example of click on a ImageView like icon and only update a single TextView (Possible to update more view in same way of same item) to show like count update after adding +1:
// View holder class inside adapter class
public class MyViewHolder extends RecyclerView.ViewHolder{
ImageView imageViewLike;
public MyViewHolder(View itemView) {
super(itemView);
imageViewLike = itemView.findViewById(R.id.imageViewLike);
imageViewLike.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int pos = getAdapterPosition(); // Get clicked item position
TextView tv = v.getRootView().findViewById(R.id.textViewLikeCount); // Find textView of recyclerView item
resultList.get(pos).setLike(resultList.get(pos).getLike() + 1); // Need to change data list to show updated data again after scrolling
tv.setText(String.valueOf(resultList.get(pos).getLike())); // Set data to TextView from updated list
}
});
}
回答9:
you just have to add following code in alert dialog box on save click
recyclerData.add(position, updateText.getText().toString());
recyclerAdapter.notifyItemChanged(position);
回答10:
The problem is RecyclerView.Adatper does not provide any methods that return the index of element
public abstract static class Adapter<VH extends ViewHolder> {
/**
* returns index of the given element in adapter, return -1 if not exist
*/
public int indexOf(Object elem);
}
My workaround is to create a map instance for (element, position)s
public class FriendAdapter extends RecyclerView.Adapter<MyViewHolder> {
private Map<Friend, Integer> posMap ;
private List<Friend> friends;
public FriendAdapter(List<Friend> friends ) {
this.friends = new ArrayList<>(friends);
this.posMap = new HashMap<>();
for(int i = 0; i < this.friends.size(); i++) {
posMap.put(this.friends.get(i), i);
}
}
public int indexOf(Friend friend) {
Integer position = this.posMap.get(elem);
return position == null ? -1 : position;
}
// skip other methods in class Adapter
}
- the element type(here class
Friend) should implementshashCode()andequals()because it is key in hashmap.
when an element changed,
void someMethod() {
Friend friend = ...;
friend.setPhoneNumber('xxxxx');
int position = friendAdapter.indexOf(friend);
friendAdapter.notifyItemChanged(position);
}
It is good to define an helper method
public class FriendAdapter extends extends RecyclerView.Adapter<MyViewHolder> {
public void friendUpdated(Friend friend) {
int position = this.indexOf(friend);
this.notifyItemChanged(position);
}
}
Map instance(Map<Friend, Integer> posMap) is not necessarily required.
If map is not used, looping throughout list can find the position of an element.
回答11:
That's also my last problem. Here my solution I use data Model and adapter for my RecyclerView
/*Firstly, register your new data to your model*/
DataModel detail = new DataModel(id, name, sat, image);
/*after that, use set to replace old value with the new one*/
int index = 4;
mData.set(index, detail);
/*finally, refresh your adapter*/
if(adapter!=null)
adapter.notifyItemChanged(index);
回答12:
if you are creating one object and adding it to the list that you use in your adapter , when you change one element of your list in the adapter all of your other items change too in other words its all about references and your list doesn't hold separate copies of that single object.
回答13:
In your RecyclerView adapter, you should have an ArrayList and also one method addItemsToList(items) to add list items to the ArrayList. Then you can add list items by call adapter.addItemsToList(items) dynamically. After all your list items added to the ArrayList then you can call adapter.notifyDataSetChanged() to display your list.
You can use the notifyDataSetChanged in the adapter for the RecyclerView
来源：https://stackoverflow.com/questions/32457406/how-to-update-refresh-specific-item-in-recyclerview