After looking for some answers here, I find myself in a disturbing situation where my Listview is really getting on my nerve.
Here are the questions I looked for :
Maintain ListView Item State
How to save state of CheckBox while scrolling in ListView?
I'm using a custom adapter with a custom row as below.
My Listview is simple as it is displaying a custom row made of three elements :
1) an ImageView displaying contact picture cropped in a circle ;
2) a TextViewdisplaying the contact full name as plain text ;
3) and finally an ImageView that holds the purpouse of a CheckBox.
Please focus on the last element. The ImageView CheckBox-like will have its src changed upon click.
When the user click, the ImageView will switch between a check sign and an unchecked sign according to it's previous status. Possible status are : {checked | unchecked}
So far so good.
But as soon as I scroll the ListView, any aforementioned change will disappear as Android recycle unused view.
Here comes the so-called ViewHolder pattern. Unfortunately, this pattern is failling me on two issues :
First, when scrolling, my organized-in-an-alphabetical-order listview gets disorganized.
e.g. somehow, whitout any reason, the first displayed contact name gets displayed again later on the ListView as I scrolled. That can happen with any row ! So it would seem unused view are being wrongly re-used.
Second, and in accordance to the first issue, the checked status do seem to stay, but not always and if it does stay, it may very well stay on the wrong row ... and that can happen randomly, of course. Therefore ViewHoder is not a viable solution.
Before discouvering the ViewHolder pattern, I have been using a HashMap to store the item position upon click as followed :
ContactsListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public final void onItemClick(final AdapterView<?> adapterView, final View view,
final int position, final long id) {
final ImageView check = (ImageView) view.findViewById(R.id.checkImage);
final TextView name = (TextView) view.findViewById(R.id.contactName);
final Boolean isChecked = Boolean.valueOf(checkedContactsList.isChecked(position));
if (isChecked != null && isChecked.booleanValue() == true) {
check.setImageDrawable(getActivity().getResources().getDrawable(R.drawable.unchecked_sign));
checkedContactsList.(position);
} else {
check.setImageDrawable(getActivity().getResources().getDrawable(R.drawable.checked_sign));
checkedContactsList.add(position, true);
}
}
});
I tried adding a different value instead of position.
I tried with ContactsListView.getPositionForView(view)
And I also tried with the View's ID, but still it doesn't work.
I wish I could use ContactsListView.getSelectedItemPosition() but it returns -1 as there is no selection event because I'm handling a touch/click event.
And this is how my Custom Adapter looks like :
public final View getView(final int position,
final View convertView, final ViewGroup parent) {
final LayoutInflater inflater = (LayoutInflater) this.context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
final View contactRowView = inflater.inflate(R.layout.contact_row, parent, false);
final ImageView contactPic = (ImageView) contactRowView.findViewById(R.id.contactPic);
final TextView contactName = (TextView) contactRowView.findViewById(R.id.contactName);
final ImageView checkImage = (ImageView) contactRowView.findViewById(R.id.checkImage);
// the list is the same as above and therefore contains the exact same entries
if (this.checkedContactsList.isChecked(position))
checkImage.setImageDrawable(this.context.getResources().getDrawable(R.drawable.checked_sign));
contactPic.setImageBitmap(cropePictureInCircle(this.contacts.get(position).getPicture()));
contactName.setText(this.contacts.get(position).getName());
return contactRowView;
}
Is there a good way to keep the checked row checked and the unchecked row unchecked in the given alphabetical order ?
Thanks !
For the list position change I know the solution but for the second problem I am still searching for a solution, anyway first make a viewHolder class;
public class ViewHolder{
//put all of your textviews and image views and
//all views here like this
TextView contactName;
ImageView checkImage;
ImageView contactImage;
}
Then edit your adapter:
#Override
public View getView(int position, View convertView, ViewGroup parent)
{
final View contactRowView = convertView;
ViewHolder holder;
if (contactRowView == null) {
final LayoutInflater inflater = (LayoutInflater)
this.context.getSystemService(Context.LAYOUT_INFLATER_SERVICE
);
contactRowView =
inflater.inflate(R.layout.contact_row, parent,
false);
holder = new ViewHolder():
holder.contactPic = (ImageView)
contactRowView.findViewById(R.id.contactPic);
holder.contactName = (TextView)
contactRowView.findViewById(R.id.contactName);
holder.checkImage = (ImageView)
contactRowView.findViewById(R.id.checkImage);
contactRowView.setTag(holder);
} else {
holder = contactRowView.getTag();
// the list is the same as above and therefore contains the exact same entries
if (this.checkedContactsList.isChecked(position))
holder.checkImage.setImageDrawable(this.context.get.
Resources().getDrawable(R.drawable.checked_sign));
holder.contactPic.setImageBitmap(cropePictureInCircle(this.contacts.get(position).getPicture()));
holder.contactName.setText(this.contacts.get(position).getName());
return contactRowView;
}
}
Hope this helps and sorry because writing code from my phone is totally awkward.
Related
I have a custom layout for a Listview, each row item contains a button that when clicked it shows a small imageview in the item, however the actions i perform in one item, repeats for another item down the list, for example, if i click the button in item 1, the imageview will show up in item 1 and item 10, if i click the button in item 2, the Imageview will show up on item 2 and item 11 and while i scroll it will keep repeating in different items, heres the code for my custom adapter:
#Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
mparent = parent;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.places_item, parent, false);
holder = new ViewHolder();
holder.placeimage = (CircularImageView) convertView.findViewById(R.id.locationimage_pilayout);
holder.addbtn = (TextView) convertView.findViewById(R.id.addbtn_pilayout);
holder.delbtn = (TextView) convertView.findViewById(R.id.delbtn_pilayout);
holder.oribtn = (TextView) convertView.findViewById(R.id.oribtn_pilayout);
holder.placename = (TextView) convertView.findViewById(R.id.locationname_pilayout);
holder.selected = (ImageView) convertView.findViewById(R.id.selected_pilayout);
holder.origin = (ImageView) convertView.findViewById(R.id.origin_pilayout);
holder.swipeLayout = (SwipeRevealLayout) convertView.findViewById(R.id.swipe_pilayout);
holder.mainLayout = (LinearLayout) convertView.findViewById(R.id.main_pilayout);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
final Place item = getItem(position);
/*
my code assigning the button click listener and assigning the views
*/
return convertView;
}
Am i missing something? im sure this could be a simple fix, but i havent found it yet. any help would be kindly appreciated.
In ListView the individual views for rows, get reused. For example, let's say the window can show up to 10 rows inside the ListView. Now when you scroll down, the 1st view gets out of the window from the top, and a new 11th view comes into the window from the bottom. In order to save memory and CPU power, Android uses the same 1st view for the 11th view. That's the purpose of convertView and the if (convertView == null) {} else {} code.
So the reason why the image is being shown in the 1st item and also in the 11th item, is that they are exactly one view object. To tackle this issue, in the getView() method, you need to reset every attribute of every view and don't rely on the defaults.
So adding a line like the one below, will get rid of the mentioned problem:
#Override
public View getView(int position, View convertView, ViewGroup parent) {
// all your code ...
holder.placeImage.setImageResource(0); //<-- This clears any previously set image.
return convertView;
}
What do I want to achieve?
In the below SS, when user touches 'vote' button, these vertical progress bars (custom) will be set according to the voting percentages retrieved from server for that particular row.
What is the obstacle?
I have onClickListener inside getView of the CustomAdapter, and when I manipulate the ProgressBar instance (which is in ViewHolder Class), supposingly I want to see the updated ProgressBar on ONLY the one row of the listview that has triggered that action, but, I see every once 3 rows that I scroll down.
Example: I clicked first row, so first row has updated its progress bar, but 4th, 7th, 10th... rows are also updated EVEN IF I don't touch 'vote button'.
My Guessing
I think this problem is related to recycling the view, the weird number is 3 in this case but when I make rows smaller it goes '4', so that is the only clue I have.
SS & Codes
ScreenShot: bit.ly/sofscreenshot
Code:
public View getView(int position, View convertView, ViewGroup parent) {
final ViewHolder holder;
LayoutInflater mInflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
if (convertView == null) {
convertView = mInflater.inflate(layout, null);
holder = new ViewHolder();
//some more initialization
holder.pb1 = (ProgressBar) convertView.findViewById(R.id.leftProgress);
holder.pb2 = (ProgressBar) convertView.findViewById(R.id.rightProgress);
holder.leftVoteButton = (Button) convertView.findViewById(R.id.leftButton);
holder.rightVoteButton = (Button) convertView.findViewById(R.id.rightButton);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.leftVoteButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
holder.pb1.setVisibility(View.VISIBLE);
holder.pb2.setVisibility(View.VISIBLE);
/Some codes...
holder.pb1.setProgress(50);
holder.pb2.setProgress(50);
}
});
}
private class ViewHolder {
//some more objects
ProgressBar pb1;
ProgressBar pb2;
Button leftVoteButton;
Button rightVoteButton;
}
All the answers and comments are appreciated, have a great day and thank you.
You're doing it wrong.
The problem is that you need to have a Model somewhere, and change its status. Then the view is updated regarding the model status.
For example, let's say that this is a "StackOverflow" app, and you have a list of answers. The user upvote the second answer. This means that the second element of the List is upvoted.
Now what?
When the adapter is going through your list of object it will "fire" the getView method for that position. Then you have to update that position according to your model. So, if the position is 1, the adapter is trying to show the second Answer, and you have to set the button to "upvoted". Otherwise you have to set it as "normal".
private List<Answer> answers;
public View getView(int position, View convertView, ViewGroup parent) {
// here get your view (or initialize it)
// get the matching answer
Answer answer = answers.get(position);
if(answer.isUpvoted()) {
holder.pb1.setVisibility(View.VISIBLE);
holder.pb2.setVisibility(View.VISIBLE);
} else {
holder.pb1.setVisibility(View.INVISIBLE);
holder.pb2.setVisibility(View.INVISIBLE);
}
holder.leftVoteButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
holder.pb1.setVisibility(View.VISIBLE);
holder.pb2.setVisibility(View.VISIBLE);
// not sure on how to get this answer here
// you probably have to go "upper" and manage the click from the ListView
answer.setUpvoted(true);
}
});
}
I want to foll list view with image grid date wise.First get Date list of image and then after get image path list of particular date wise image list.and finally I fill list and grid of particular date wise image(No of images and date not fixed),have a look screen shot.
Date wise images display in Grid View
And now my problem is, When I set click listener on image and add check mark image on click then image add in two position, Why I don't know.and second is when I scroll down list view then check mark visible gone.
I want to select multiple image and add check mark image and perform operation like "Delete image" and "Share image"
Like this
I call grid adapter of each list item , look my code tell me what's wrong
Custom List View adapter : get View method
#Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
View row = convertView;
ViewHolder viewHolder = new ViewHolder();
DateSortedImageItem item = getItem(position);
if (row == null) {
row = mInflator.inflate(R.layout.row_date_sorted_image_list, parent, false);
viewHolder.tv_date = (TextView) row.findViewById(R.id.tv_row_date);
viewHolder.rowGridView = (GridView) row.findViewById(R.id.gv_row_item);
viewHolder.tv_date.setText(item.getDate());
row.setTag(viewHolder);
gridAdapter = new GridAdapter(context, R.layout.row_sorted_image_gridview_item,
item.getDateSortedImageList(), position);
viewHolder.rowGridView.setAdapter(gridAdapter);
} else {
row.getTag();
}
return row;
}
private class ViewHolder {
TextView tv_date;
GridView rowGridView;
}
and my grid adapter code is :
public View getView(final int position, View convertView, ViewGroup parent) {
if (convertView == null) {
LayoutInflater mInflater = ((Activity) getContext()).getLayoutInflater();
convertView = mInflater.inflate(R.layout.row_sorted_image_gridview_item, parent, false);
}
view = convertView;
final SquareImageView imageView = (SquareImageView) view.findViewById(R.id.iv_test_row_grid_img);
final ImageView iv_checked = (ImageView) view.findViewById(R.id.iv_checked);
final ImageView iv_unChecked = (ImageView) view.findViewById(R.id.iv_unchecked);
view.setTag(arrList.get(position).toString());
File f = new File(arrList.get(position).toString());
System.out.println("arrList size >>" + arrList.size());
Picasso.with(context).load(Uri.fromFile(f)).resize(100, 100).centerCrop().placeholder(R.drawable.ic_launcher)
.error(R.drawable.ic_close_black).into(imageView);
I just set Grid View image. And now i set imageview click ivent and add check mark then add check mark event two places and scroll down then visible gone also.
What's wrong hear and how to set click event of image view unique.
Finally I want to design Look like Google "Photos" app.
Suggest me any example or library:
First you should create a POJO as below
public class AlbumItem {
private String headerStr;
private List<ChildItem> children;
//getter - setter....
public class ChildItem {
private String childName;
private boolean isSelected;
//getter - setter.....
}
}
Now use this POJO inside your main adapter.
and in the second adapter handle the selection logic means if isSelected is true then show iv_checked otherwise show iv_unchecked.
Please let me know if you need further explanation.
Hope it will help you.
I have the following situation.
I have a ListView, each item of the ListView is comprised of different widgets (TextViews, ImageViews, etc...) inflated form a Layout in the getView() method of the custom adapter.
Now, I would like to achieve the following:
when a certain event is triggered I want to change the background of a View which is inside the item.
Please how do I do it?
This is the the Item Layout:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/cardlayout"
android:layout_width="320dp"
android:layout_height="130dp"
android:background="#android:color/transparent"
android:orientation="vertical"
android:paddingBottom="5dp"
android:paddingRight="5dp"
android:paddingTop="5dp" >
<FrameLayout
android:layout_width="320dp"
android:layout_height="117dp" >
<View
android:id="#+id/card"
android:layout_width="320dp"
android:layout_height="117dp"
android:background="#drawable/card_selector" />
</FrameLayout>
</LinearLayout>
I need to change the background of card
I have tried doing this:
View v=lv.getAdapter().getView(index, null, lv);
View card =(View)v.findViewById(R.id.card);
card.setBackgroundResource(R.drawable.pressed_background_card);
But no success :-((
When your event is triggered you should just call a notifyDataSetChanged on your adapter so that it will call again getView for all your visible elements.
Your getView method should take into account that some elements may have different background colors (and not forget to set it to normal color if the element doesn't need the changed background, else with recycling you would have many elements with changed background when you scroll)
edit :
I would try something like this :
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if(convertView == null)
{
convertView = LayoutInflater.from(getContext()).inflate(R.layout.card, parent, false);
}
//This part should also be optimised with a ViewHolder
//because findViewById is a costly operation, but that's not the point of this example
CardView cardView =(CardView)convertView .findViewById(R.id.card);
//I suppose your card should be determined by your adapter, not a new one each time
Card card = getItem(position);
//here you should check sthg like the position presence in a map or a special state of your card object
if(mapCardWithSpecialBackground.contains(position))
{
card.setBackgroundResource(specialBackground);
}
else
{
card.setBackgroundResource(normalBackground);
}
cardView.setCard(card);
return convertView;
}
And on the special event i would add the position of the item into the map and call notifyDataSetChanged.
Use the onitemclicklistener which has method onclicksomething..that takes four or five parameters. (View parent, View view, int position, int id). Use the view parameter to customize your background.
Update
Here's some of my code, If you don't understand I recommend to read about recycling and ViewHolder pattern.
#Override
public View getView(int position, View convertView, ViewGroup parent) {
{
ViewHolder viewHolder;
// If convertView isn't a recycled view, create a new.
if(convertView == null){
LayoutInflater inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate(R.layout.row_gallery_frame, parent, false);
viewHolder = new ViewHolder();
// Here you must be able to find your Widget inside convertView and set a listener to it I guess?
viewHolder.nameHolder = (TextView) convertView.findViewById(R.id.nameTv);
// Set a reference to newly inflated view
convertView.setTag(viewHolder);
}
// If it is, then get the ViewHolder by tag
else{
viewHolder = (ViewHolder)convertView.getTag();
}
// Set the data
GalleryFrame galleryFrame = galleryFrameArrayList.get(position);
viewHolder.nameHolder.setText(galleryFrame.getName());
return convertView;
}
}
// Viewholder pattern which holds all widgets used
public static class ViewHolder{
public TextView nameHolder;
}
I assume you have a model object that you use to "draw" the list item , and for example the background color is determined based on a boolean or something.
All you need to do, is change the value on which you base your decision which background color should that TextView have.
Your getView() method should have code like that
if (myModelObj.isBrown()) {
myTextView.setBackgroundResource(R.drawable.brown_bg);
else
myTextView.setBackgroundResource(R.drawable.not_brown_bg);
All you should do when ur event is triggered, is set the value of the brown boolean in your model
and call notifyDataSetChanged() on your adapter
EDIT
If for some reason you don't wanna call nofitfyDataSetChanged(), althought it won't move the scroll position of your list and with the right recyclying it won't cause bad performance
You can find the View object that represent the list item you want to edit-if it's visisble-, and simply change the background in it, without refreshing the list at all.
int wantedPosition = 10; // Whatever position you're looking for
int firstPosition = listView.getFirstVisiblePosition() - listView.getHeaderViewsCount();
int wantedChild = wantedPosition - firstPosition
if (wantedChild < 0 || wantedChild >= listView.getChildCount()) {
// Wanted item isn't displayed
return;
}
View wantedView = listView.getChildAt(wantedChild);
then use wantedView to edit your background
This answer can be found here
try this one:
View v=lv.getAdapter().getView(index, null, lv);
View card =(View)v.findViewById(R.id.card);
card.setBackgroundResource(R.drawable.pressed_background_card);
card.invalidate();
v.invalidate();
those function force your views to redraw itself and they will render again.
look at invalidate()
What I normally do is this:
public static class EventDetailsRenderer {
private TextView title;
private TextView description;
private Event item;
public EventDetailsRenderer(View view) {
extractFromView(view);
}
private final void extractFromView(View view) {
title = (TextView) view.findViewById(R.id.EventTitle);
description = (TextView) view.findViewById(R.id.Description);
}
public final void render() {
render(item);
}
public final void render(Event item) {
this.item= item;
title.setText(item.getTitle());
description.setText(item.getDescription());
}
}
private class EventsAdapter
extends ArrayAdapter<Event> {
public EventsAdapter(Context context) {
super(context, R.layout.list_node__event_details, 0);
}
public void addAllItems(Event... services) {
for (int i = 0; i < services.length; i++) {
add(services[i]);
}
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
Event event = getItem(position);
EventDetailsRenderer eventRenderer;
if (convertView != null && convertView.getTag() != null) {
eventRenderer = (EventDetailsRenderer) convertView.getTag();
} else {
convertView = getActivity().getLayoutInflater().inflate(R.layout.list_node__event_details, null);
eventRenderer = new EventDetailsRenderer(convertView);
convertView.setTag(eventRenderer);
}
eventRenderer.render(event);
return convertView;
}
}
NOTE: that this example might not compile I pasted it from some code I have and deleted some lines to show an example but the logic it the same.
And then when you want to render it, just get the children from the list, iterate over them, check if the renderer contains the card you want to flip and call its render method... then you render a specific item in the list without effecting the rest of the items.
Let me know if this works...
Adam.
User EasyListViewAdapters library https://github.com/birajpatel/EasyListViewAdapters
Features
Easier than implementing your own Adapter (ie handling
BaseAdaper#getView).Very Easier to provide multi-row support.
Library takes care of recycling all views, that ensures performance
& helps your list view scroll smoothly.
Cleaner code. By keeping different RowViewSetter classes for
different row-types makes your code easy to manage & easy to reuse.
No data browsing, Library takes care of browsing data through
data-structure when View is being drawn or event occurs so that
Users does not have to look for their data to take actions.
Just by passing correct row-types library will Auto-map your
data-types to row-types to render views. Row views can be created by
using XML or Java (doesn't restrict to XML-Only Approach).
Load More callbacks can be registered to implement paginatation
support to your list.
Handling children viewclicks, you can also register for
Children(present inside your rows) view click events.
All these Views are registered with single OnClickListner so that
this mechanism is very memory efficient when click event occurs
users you gets clickedChildView, rowData,int eventId as callback
params.
I use even and odd rows to set backgrond to my listview rows. In my efficientAdapter I set the row background as follows:
public View getView(int position, View convertView, ViewGroup parent) {
vi = convertView;
if (convertView == null) {
vi = inflater.inflate(R.layout.ecran_multiple_row, null);
holder = new ViewHolder();
holder.txIndex = (TextView) vi.findViewById(R.id.txIndex);
holder.txSTitle = (TextView) vi.findViewById(R.id.txSTitle);
holder.btOnOFF = (ImageView) vi.findViewById(R.id.btOnOFF);
vi.setTag(holder);
} else
holder = (ViewHolder) vi.getTag();
/*
* CHANGE ROW COLOR 0 WHITE 1 GRAY
*/
if ( position % 2 == 0) //0 even 1 odd..
vi.setBackgroundResource(R.drawable.listview_selector_odd);
else
vi.setBackgroundResource(R.drawable.listview_selector_even);
/*
* ONE ITEM IN ARRAY
*/
if (data.toArray().length==1){
holder.btOnOFF.setBackgroundResource(R.drawable.air_radio_button_rouge);
}else {
holder.btOnOFF.setBackgroundResource(R.drawable.air_deezer_check);
}
return vi;
}
and in my MainActivity.Class. I select an item using on itemclicklistener() as shown below:
**lvRMultiple.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
imgview = (ImageView) view.findViewById(R.id.btOnOFF);
//And change its background here
imgview.setBackgroundResource(R.drawable.air_radio_button_rouge);
}
});**
When i clicked on an item btnOff image change successfully but when i scroll down it change to default background. Secondly when i click on one item after the other both becomes the new image but i want only the row clicked by the user to change to new image and the previous image are set to default.
All row view of a ListView created by the getView() method of BaseAdpter class. When ever we scroll the ListView all, new viable row create by getView() using recycle. So getView() called again and again when new row is viable on scroll.
There are two solution of your question:-\
You can save the status of ListView
// Save ListView state
Parcelable state = listView.onSaveInstanceState();
// Set new items
listView.setAdapter(adapter);
// Restore previous state (including selected item index and scroll position)
listView.onRestoreInstanceState(state)
And other solution is create RowView at runtime and add it on a Parent Layout by using addView() method.
LayoutInflater inflater = LayoutInflater.from(context);
// You should use the LinerLayout instead of the listview, and parent Layout should be inside of the ScrollView
parentView = (LinerLayout)this.findViewById(R.id.parentView);
for(int i = 0; i<=numberOfRow;i++){
LinearLayout rowView = (LinerLayout)inflater.inflate(R.layout.rowView);
ImageView rowImageView = (ImageView)rowView.findViewById(R.id.rowImage);
rowImageView.setOnClickListener(new View.onClickListListener(){
#Override
public void onClick(){
rowImageView.setImageBitmap(onClickBitmapImage);
}
});
parentView.addView(rowView);
}
Please check this answer Maintain/Save/Restore scroll position when returning to a ListView
More Reference
http://developer.android.com/reference/android/widget/Adapter.html#getView(int,android.view.View, android.view.ViewGroup)
The item changes back to the default background because the view gets recycled. This is the same problems of checkboxes losing their checked state
Check out this answer too see how to handle it:
CheckBox gets unchecked on scroll in a custom listview
As for your second problem, I believe it's already answered here:
highlighting the selected item in the listview in android
Hope it helps