I'm trying to implement a custom listview. Everything works fine until I use a if () statement inside the getView() method
Without the if() condition a single item gets selected when I select an item but when I add the if() condition, the views are displayed properly but two items (non-adjacent) get selected (1st and last 1st or and second-last, any such combination).
View getView(...){
....
if (!item.getPriceTo().equals(""))
priceToTV.setText(item.getPriceTo());
else
priceToTV.setText(item.getPriceFrom());
return view;
}
Also I'm using saving the previous view to show the selection so the current selection has a red_border and when it is selected a black_border is set to it.:
subItemsListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
Log.d("New Order", "........");
if (previousViewOfSubItems != null && previousViewOfSubItems != view) {
previousViewOfSubItems.setBackgroundResource(R.drawable.black_border);
if (quantity.getText().toString().equals("xx") || quantity.getText().toString().equals("0")) {
viewForVisibility.setVisibility(View.GONE);
layoutForQuantity.setVisibility(View.GONE);
}
}
if (previousViewOfSubItems == view)
return;
previousViewOfSubItems = view;
previousViewOfSubItems.setBackgroundResource(R.drawable.red_border);
viewForVisibility = previousViewOfSubItems.findViewById(R.id.viewForVisibility);
viewForVisibility.setVisibility(View.VISIBLE);
layoutForQuantity = (LinearLayout) previousViewOfSubItems.findViewById(R.id.layoutForQuantity);
layoutForQuantity.setVisibility(View.VISIBLE);
quantity = (TextView) previousViewOfSubItems.findViewById(R.id.subTypeQuantity);
}
});
previousViewOfSubItems = view; seems to be causing the problem,
In Listviews with adapter you should avoid saving view instances, because views are reused by adapters so view can be same for two rows so rather than saving view instance's reference use ViewHolder Design pattern and use view tagging
You need to use ViewHolder Pattern and view tagging to properly identify every view in different position. ListView always recycle the view instead of re-inflating the view again and again.
You can refer to Android Training documentation on how to implement ViewHolder pattern.
ListViews recycle the views in the list. so as you scroll, top views are reused and content replaced using the methods.
Where you set background to Red etc, use Else statements to set it back to your default black.
its beacause it listview reuses view to display items, once the first view is scrolled out the the same view is reused to display the view at bottom of the listview. instead of comparing the view try compairing the position of the view clicked
I have explained about this abnormal behavior in my blog on recyclerview you refer that to solve this problem.
use pojo class to get the status and update the view accordingly
Related
The Problem
My way to add the view makes every fifth item to add the view when i only want one position to have this "Mängd" row.
Why Can i only edit listitems when they are visible on the screen.
The child will be static at 5 items even though i got like 20 item....
Is there any way to only say that item 1 will have this and not
position - firstvisibleposition
i think this is the problem with the listview
My code is not understandable at the time because of other things so i hope you get my problem anyways.
This is my main question
It seems like the thing i add to position 0 also happens to 6 and 12 Why is ListView this wierd ?
It's on swedish, but this is what i got with list view.
Every listview item has a empty Linearlayout that i add a view to when i press the down arrow button. the problem is that every fifth item gets this or i can only click on the first 5.
I dont get why they make ListView so complicated. i want to be able to get a child that is in the list without seening it!
CODE getView
public View getView (int position, View convertView, ViewGroup parent){
if (convertView == null)
{
convertView = LayoutInflater.from(getContext()).inflate(R.layout.view_meal_item_editable, null);
}
convertView.setOnTouchListener(new ItemSwipeListener(position,
getResources().getDisplayMetrics().density));
convertView.setClickable(true);
// Lookup view for data population
TextView food_item_name = (TextView) convertView.findViewById(R.id.food_item_name);
food_item_name.setHint("hello");
}
Where i add the view
View view = searchResultList.getAdapter().getView(position, searchResultList.getChildAt(position - searchResultList.getFirstVisiblePosition()), searchResultList);
LinearLayout extendedView = (LinearLayout)view.findViewById(R.id.extended_food_information);
View convertExtendedView = LayoutInflater.from(this).inflate(R.layout.change_amount_on_food_view, null);
extendedView.addView(convertExtendedView);
It's recommended to use a header view if you do this stuff only for the first element.
Otherwise it will be better if you add your extra view in getView() method, something like:
if(position==0){
// add extra view
} else {
// remove extra view if exist
}
Or you can remove the IF condition: if (convertView == null), so you will inflate a new layout each time, it will solve your problem but this is not good for list performance
The following is part of my code for onBindViewHolder (inside MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder>)
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
// - get element from your dataset at this position
StatusItem item = mDataset.get(position);
//......
//Add content and timing to the textview
String content = item.getContent();
holder.mTextViewTime.setText(timing);
//Set the img
holder.imgViewIcon.setImageDrawable(item.getProfileDrawable());
//Set content image (for Instagram)
holder.mImageViewContentPic.setImageDrawable(item.getContentDrawable());
//HIDE THE VIEW Start
if(item.getContentDrawable() == null){
holder.mImageViewContentPic.setVisibility(View.GONE);
}
//HIDE THE VIEW End
}
The part HIDE THE VIEW is not working as expected.
When I am scrolling downwards, the views are working normally. However, when I start to scroll upwards, i.e. revisited the previous views, the ImageViews that are supposed to be VISIBLE becomes GONE, although I checked my dataset and verified that it has not been modified. Try calling other methods on the views also give erratic results(positions and items in dataset do not match).
It seems that the view holders are not binded to specific positions inside the RecyclerView.
The code works as expected if I remove the HIDE THE VIEW part.
Is there any way to solve this issue and dynamically hide views in my case?
Note: I used some AsyncTasks to update the dataset and call notifyDataSetChanged(), if that is relevant.
###This is the solution to your problem:###
holder.mImageViewContentPic.setVisibility(View.VISIBLE);
if(item.getContentDrawable() == null){
holder.mImageViewContentPic.setVisibility(View.GONE);
}
Because RecyclerView use recycle very well, ViewHolder A may be used to be ViewHolder B, so you need to specific every attribute of a ViewHolder in case of some attributes attach to a wrong object.
In my android app my Main Activity extends List Activity. I store there elements called Items, their layout is defined by itemLayout xml file and I use custom adapter (called ItemAdapter) to transfer data to List View in Main Activity. In itemLayout there's an ImageView and my aim is to change its image when user clicks on the particular item in list view. In my opinion the easiest way to achieve that is to get access to particular item's (the one that was clicked) layout, there find the ImageView and call method setImageBitmap. How can I "find" this layout of clicked item? I tried many things in method:
#Override
protected void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
}
but nothing worked. Do I have to add anything to my ItemAdapter? Or is it possible to do in onListItemClick(…) but I can't find out how?
You're thinking about it in slightly the wrong way. Adapter's are a way to map data to views. So if you want to change how a particular view looks for a given position, you need to change it's correlating data so that the rendered View then changes. Attempting to modify a view directly kinda goes against how adapters are meant to be used.
So in your case, when a user clicks on an item. Find that item in your adapter via the position number. Then update the item and ensure notifydataset is called. Meanwhile, your adapter's getView() will then handle displaying the appropriate image.
As I understood you need to modify clicked item layout, right? Use argument from onListItemClicked:
v.findViewById(<your_img_view_id>)
For better performance use view holder.
onListItemClick is fired when you press on an element of the ListView. If you want to retrieve the element in the dataset, you can simply invoke
l.getItemAtPosition(position)
the returned value has to be casted to the specific object
Yes It is possible in your custom adapter class in the getView() mtheod u can change imageview bitmap by clicking on it
see this code
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
View rowView = convertView;
rowView = inflater.inflate(R.layout.playlist_item, null);
final ImageView im = (ImageView) rowView.findViewById(R.id.favorite);
im.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// Do your stuff here
}
});
return rowView;
}
(I have already seen this similar question)
I have a ListView for which I've written a custom adapter, and an onitemclicklistener. I'm having an issue where, when any element of the list is selected, getView is called (twice) for each of the top 4 elements of the ListView, even if those elements are not visible. This happens even if I don't call notifyDataSetChanged on the adapter - those first 4 views are fetched twice regardless. Is this normal behavior? My issue is not as much that it's being called twice for them, but that it is being called at all when updating them is not needed.
By the way, I am not using wrap_content for the height or width of the listview - the height is match_parent and the width is a fixed number of dp.
The onItemClick() method of the OnItemClickListener is here:
public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
mPicture = pictures[position];
mPicturesAdapter.setCurrentPicture(mPicture);
mPicturesAdapter.notifyDataSetChanged();
}
getView() from my custom Adapter (which extends BaseAdapter) is here:
public View getView(int position, View convertView, ViewGroup parent) {
Log.v("tag", "Getting view for position "+position);
LayoutInflater inflater = LayoutInflater.from(mContext);
LinearLayout layout = (LinearLayout)
inflater.inflate(R.layout.picture_thumbnail, parent, false);
// set up the linearlayout here ...
return layout;
}
On any item click, getView() is called for positions 0 - 3 twice regardless of which item was clicked.
Just by modifying the adapter via
mPicturesAdapter.setCurrentPicture(mPicture);
the ListView already tries to update itself. I'm guessing the onClick method will still do it's job without you calling notifyDataSetChanged
Actually whatever List/Group you are using to populate the ListView, you need to first empty it and then recall it. For example, if you use ListA to populate the ListView, in the second or any consecutive update you need to empty the ListA first and then add items and then populate using it.
if (convertView != null){
Then populate list
}
I am developing an application in which I have to show ratings depending on the values that I am receiving after parsing the XML response in listview. I have implemented it using the Custom Adapter and showing the images in the getView() method like :
String rating = Constants.menuRatingList.get(position);
if (rating.equals("1")) {
rateImg1.setImageResource(R.drawable.stary);
}
The problem is when I scroll the down to the last item and again move upwards, it is redrawing the list row.
Someone please suggest me approach to stop the redrawing the list row and set the image value permanently.
How do you create the rateImg1 variable?
Maybe you should get it from the view that is passed to the getView() method?
Something like this:
public View getView(int position, View view, ViewGroup parent) {
if (view == null) {
view = LayoutInflater.from(ctx).inflate(R.layout.my_layout, parent, false);
}
((ImageView) view.findViewById(R.id.my_image)).setImageResource(R.drawable.some_drawable);
return view;
}
Also you can implement getViewTypeCount() and getItemViewType() and check them in the above method not to redraw the same image if it is already set.