I've got a ListView, each of item of which contains a ToggleButton. After I toggle it and then scroll up or down, the ListView is recycling the Views and so some of the others are mirroring the checked state of the ToggleButton. I don't want this. How can I prevent it?
Add this two methods to your Adapter.
#Override
public int getViewTypeCount() {
return getCount();
}
#Override
public int getItemViewType(int position) {
return position;
}
Android recycles list items for performance purposes. It is highly recommended to reuse them if you want your ListView to scroll smoothly.
For each list item the getView function of your adapter is called. There, is where you have to assign the values for the item the ListView is asking for.
Have a look at this example:
#Override
public View getView(int position, View convertView, ViewGroup parent)
{
ViewHolder holder = null;
if ( convertView == null )
{
/* There is no view at this position, we create a new one.
In this case by inflating an xml layout */
convertView = mInflater.inflate(R.layout.listview_item, null);
holder = new ViewHolder();
holder.toggleOk = (ToggleButton) convertView.findViewById( R.id.togOk );
convertView.setTag (holder);
}
else
{
/* We recycle a View that already exists */
holder = (ViewHolder) convertView.getTag ();
}
// Once we have a reference to the View we are returning, we set its values.
// Here is where you should set the ToggleButton value for this item!!!
holder.toggleOk.setChecked( mToggles.get( position ) );
return convertView;
}
Notice that ViewHolder is a static class we use to recycle that view. Its properties are the views your list item has. It is declared in your adapter.
static class ViewHolder{
ToggleButton toggleOk;
}
mToggles is declared as a private property in your adapter and set with a public method like this:
public void setToggleList( ArrayList<Boolean> list ){
this.mToggles = list;
notifyDataSetChanged();
}
Have a look at other custom ListView examples for more information.
Hope it helps.
You could use a HashMap to save your buttons state:
private Map<Integer,Boolean> listMapBoolean = new HashMap<Integer,Boolean>();
toggleButton.setOnCheckedChangeListener(new OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if (isChecked) {
listMapBoolean.put(position, true);
} else {
listMapBoolean.put(position, false);
}
}
});
and after inflating the view you read the HashMap to see if it was checked or not:
for (Entry<Integer, Boolean> entry : listMapBoolean.entrySet()) {
if (entry.getKey().equals(i)) {
if(entry.getValue()) {
System.out.println("ToggleButton is checked!");
} else {
System.out.println("ToggleButton is not checked!");
}
}
}
Not sure if it helps in your way. I had also problems with recycling my EditText in my ListView.
This would make it so slow for large lists. But inside getView(), you can use:
if (listItemView == null || ((int)listItemView.getTag()!=position)) {
listItemView = LayoutInflater.from(context).inflate(R.layout.edit_text_list_item,
parent, false);
}
listItemView.setTag(position);
// set inner Views data from ArrayList
...
The tag is an Object that is associated with the View. And you check whenever you recycle it if you can recycle it or not. This makes each list item be inflated and nothing will be recycled.
This also should prevent deleting text from EditText inside the ListView and also prevent images from being reordered or messed up if your ListView has images in it.
May be you should try creating your own list view with scroll view and a container that holds the children that are added to the container programatically. set the tag for identifying the child or you could use the order of the child for that
Related
I have a listview with a checked textview and two textviews,however, my getView method keeps changing the listview items while scrolling, the values and checkbox states are both saved into sqlite database. I tried every possible solution and spent 4 hours trying to fix that.
Any help appreciated.The only solution that worked was setting convertview to null at beginning of getView() which lags the listview.
GOAL:to make listview display items properly without changing its positions randomly.
Final working code for anyone in need:
#Override
public View getView( final int position, View convertView, ViewGroup parent) {
viewHolder = null;
if(convertView == null){
convertView = inflater.inflate(R.layout.sin_item,null);
viewHolder = new HolderCo();
viewHolder.box = (CheckBox)convertView.findViewById(R.id.coco);
viewHolder.subject = (TextView)convertView.findViewById(R.id.subject_com);
viewHolder.date = (TextView)convertView.findViewById(R.id.date_co);
convertView.setTag(viewHolder);
}
else{
viewHolder = (HolderCo)convertView.getTag();
}
viewHolder.position = position;
viewHolder.box.setText(list.get(viewHolder.position).getWhats());
viewHolder.subject.setText(list.get(viewHolder.position).getSubject());
if(list.get(viewHolder.position).isSelected()) {
viewHolder.box.setOnCheckedChangeListener(null);
viewHolder.box.setChecked(true);
viewHolder.box.setPaintFlags(viewHolder.box.getPaintFlags() | Paint.STRIKE_THRU_TEXT_FLAG);
}else{
viewHolder.box.setOnCheckedChangeListener(null);
viewHolder.box.setChecked(false);
viewHolder.box.setPaintFlags(viewHolder.box.getPaintFlags() & (~Paint.STRIKE_THRU_TEXT_FLAG));
}
if(dator.equals("d"))
viewHolder.date.setText(list.get(viewHolder.position).getDay()+"/"+list.get(viewHolder.position).getMonth()+"/"+list.get(viewHolder.position).getYear());
if(dator.equals("m"))
viewHolder.date.setText(list.get(viewHolder.position).getMonth()+"/"+list.get(viewHolder.position).getDay()+"/"+list.get(viewHolder.position).getYear());
if(dator.equals("y"))
viewHolder.date.setText(list.get(viewHolder.position).getYear()+"/"+list.get(viewHolder.position).getMonth()+"/"+list.get(viewHolder.position).getDay());
viewHolder.box.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if(buttonView.isChecked()) {
list.get(position).setSelected(true);
db.updateState(list.get(position),true);
buttonView.setPaintFlags(buttonView.getPaintFlags()| Paint.STRIKE_THRU_TEXT_FLAG);
if(PreferenceManager.getDefaultSharedPreferences(ctx).getBoolean("add_mark_dialog",true))
buttonView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
dialoging(viewHolder.position);
}
});
}else{
buttonView.setOnClickListener(null);
list.get(position).setSelected(false);
db.updateState(list.get(position), false);
buttonView.setPaintFlags(buttonView.getPaintFlags()&(~Paint.STRIKE_THRU_TEXT_FLAG));
}
}
});
return convertView;
}
By doing this:
viewHolder.box.setTag(position);
viewHolder.date.setTag(position);
viewHolder.subject.setTag(position);
you set the tags to the views to the first position they were created with.
So when getView() is called with non-null convertView (previously recycled), the tags in its viewHolder still point to that position.
Move these setTag() calls outside if(), to set new position to recycled view.
BTW I would rather replace all this with
viewHolder.position = position; // outside if()
and using it everywhere you use (Integer)x.getTag()
UPDATE: Also you have to do this:
viewHolder.box.setOnCheckedChangeListener(null);
before this:
viewHolder.box.setChecked(...);
Because otherwise it can trigger previous listener which most likely you don't want.
You're updating the view conditionally with if conditions. You need to provide corresponding else blocks where you reset the view to their default values.
For example,
if(dator.equals("d"))
viewHolder.date.setText(...);
if(dator.equals("m"))
viewHolder.date.setText(...);
if(dator.equals("y"))
viewHolder.date.setText(...);
needs to be something like
if(dator.equals("d"))
viewHolder.date.setText(...);
else if(dator.equals("m"))
viewHolder.date.setText(...);
else if(dator.equals("y"))
viewHolder.date.setText(...);
else
viewHolder.date.setText("some default value");
Similarly reset defaults in viewHolder.box.setPaintFlags().
The reason is that ListView views are recycled. Recycled views are not in their pristine state like they were immediately after inflation. Instead they will be in a state they were before they were recycled, possibly containing data from the list row previously using that view.
I have a custom listview with item layout having a checkbox at the left and 4 textviews much like astrid task manager.
What I intend to do is that on clicking the checkbox, the textviews have to update their values. At first, my problem was that on checking a checkbox at position 1 would check the checkbox at the end or somewhere else while scrolling. While searching for a solution, I came to know about recycling of view in listview. I applied those concepts like viewholder and right now I am able to maintain the state of checkbox. But, on checkbox click, I change the textviews and the change is not persisting, meaning any random tv also shows the same change.
I have applied a checkbox onclicklistener in my adapter. Any ideas how to achieve it?
You will want to persist the state of the item in your item data rather than in the view holder. The view holder is just a convenience to the view, which at various times will display many different items, assuming you recycle the views. During the data binding, you will want to bind all state necessary for displaying your item to avoid having random data appearing in another list item's view.
public class MyListAdapter extends BaseAdapter {
// ....
#Override
View getView(final int position, View convertView, ViewGroup parent) {
View view = convertView;
if (view == null) {
view = inflate(R.layout.my_list_item_layout, parent, false);
// View holder just prevents having to look up these values
// every time the view is reused.
MyViewHolder holder = new MyViewHolder();
holder.checkbox = (CheckBox) view.findViewById(R.id.check_box);
holder.textview = (TextView) view.findViewById(R.id.text_view);
view.setTag(holder);
}
final MyViewHolder holder = (MyViewHolder) view.getTag();
final MyData data = (MyData) getItem(position);
holder.checkbox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
data.savedCheckboxState = isChecked;
// now tell the view to rebind the data
notifyDataSetChanged();
}
});
holder.checkbox.setChecked(data.savedCheckboxState);
holder.textview.setText(String.valueOf(data.savedCheckboxState));
return view;
}
private static class MyViewHolder {
CheckBox checkbox;
TextView textview;
}
}
You can refer to my full code here, what you can do is,store check box state in a boolean array then you wont face this issue.....
Android checkbox multiselected issue
I had a ListView with images that are loading by using ImageLoader(framework) and checkbox for each image.I had a adapter that is extending BaseAdapter for this ListView,when i'm checking one of the checkbox and scrolling it then i see other checkboxes which are automatically checked. Is there any way to resolve my issue. Please someone give me a clue or example.
This is because the rows are being re-used, so you need to set some attribute for each row telling it whether that row is checked or not. And then make "if and else" statement in your getView() to look if that row is checked or not, and if it is just check it, otherwise leave it unchecked.
I would suggest you use an array of booleans where you keep your checked state for every position in the list. ListView recreates list elements on scroll, so your checks could be messed up. This means that you have to check if boolean value for position of the element you're instantiating is true and then use checkBox.setChecked(true), or checkBox.setChecked(false).
Simple,
Set<String> bs = new HashSet(String);
String[] bid;
And write this in you getView method, Take it as a template. Not as a solution
public View getView(final int position, View convertView, ViewGroup arg2) {
row = convertView;
if (row == null)
{
LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = vi.inflate(R.layout.your_listview,null);
}
check = (CheckBox) row.findViewById(R.id.your_checkboxid);
check.setOnCheckedChangeListener(new OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if(isChecked)
{
bs.add(bid[position]);
}
else
{
if(bs.contains(bid[position]))
{
bs.remove(bid[position]);
}
}
}
});
if(bs.contains(bid[position]))
{
check.setChecked(true);
}
else
{
check.setChecked(false);
}
return row;
}
I'm trying to create a custom list which will have checkboxes that allow you to select several items from the list.
The list with the checkboxes is displayed ok but if i check a checkbox and then scroll other items further down the list are also checked.
Its basically the same problem as here
I understand that it has something to do with the way android recycles the view but I cant see how to fix this! Can somebody help me???
Thanks -- Mike
You need a data structure to keep track of which rows are checked. This could be as simple as a bool[] checked.
In your getView, make sure that you set the checkbox state to the contents of checked[position]. You should also set an OnCheckedChangedListener on your check boxes in getView so that they update your data with checked[position] = isChecked.
Yes, the rows in a ListView are recycled, so make sure to populate all the appropriate data for a row before you leave getView.
You could try implementing OnClickListener for checkbox instead of OnCheckChangedListener. It worked for me.
Create an ArrayList<Integer>. add a OnCheckChangedListener to your checkbox. Inside the changed method, add or remove the list view position to the ArrayList<Integer>.
in your getView method, check to see if the ArrayList<Integer> contains the current list view position. if it contains the position, set checked to true, otherwise false.
every time you click a checkbox, either add or remove the Integer from the ArrayList.
Check the code below -
public View getView(int position, View convertView, ViewGroup parent){
View view = convertView;
ViewHolder holder = new ViewHolder();
if(view == null){
view = inflater.inflate(R.layout.list_callcycle_blue, null);
holder.llContainer = (LinearLayout) view.findViewById(R.id.ll_container);
holder.lblLabel = (TextView) view.findViewById(R.id.txt_desc);
holder.cb = (CheckBox) view.findViewById(R.id.cb_store);
view.setTag(holder);
} else {
holder = (ViewHolder) view.getTag();
}
final Object data = getItem(position);
holder.lblLabel.setText(data.getDescription());
holder.cb.setTag(position);
holder.cb.setOnCheckedChangeListener(new OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
int position = (Integer) buttonView.getTag();
objects.get(position).setChecked(buttonView.isChecked());
}
});
holder.cb.setChecked(isChecked(position));
return view;
}
Always keep in mind, use change holder.cb.setOnCheckedChangeListener() i.e. any listener before it's setting data, in our case it is holder.cb.setChecked()
Reason : When we scroll, listview will recycle the views, so if setchecked is used before listeners then it will pick values on the basis of old listener. And if we set it after listener, then it will take latest values
EDITED PART
Below part will show how isChecked() and setChecked() methods used for retrieving checked data
/*
* This function is in your Custom Adapter Class
*/
private boolean isChecked(int position){
return object(position).isChecked();
}
/**
* Getter Setter Class / Data Model Class that defines your object
*/
private class MyObject{
private boolean isChecked;
private String a, b, c, orWhateverYourObjectNeeds;
public void setChecked(boolean isChecked){
this.isChecked = isChecked;
}
public boolean isChecked(){
return isChecked
}
}
An activity has a Button and a ListView.
Initially, only the Button is visible. When the button is pressed, the ListView is displayed.
When displayed, is it possible for me to show one particular item as selected/focussed?
A use case could be that suppose it is a list of language settings and when the list opens, the currently selected language must be shown as highlighted.
If I know the index of the item, how to set it as focused on display?
I post my solution, because google still doesn't know the answer.
getListView().setItemChecked(selectedGroupIndex, true);
In short, ListView::setSelection(int position) is what you need. However, depending on whether the device is in touch mode or not, it may or may not have visual effect (background highlighting). For more details, refer to Android ListView Selection Problem
If you use an Adapter for your ListView add this code to your adapter:
public class MyAdapter extends ArrayAdapter<MyClass> {
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if (convertView == null) {
LayoutInflater inflator = (LayoutInflater) getContext()
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
rowView = inflator.inflate(R.layout.my_adapter, null);
} else {
rowView = (View) convertView;
}
//...
// set selected item
LinearLayout ActiveItem = (LinearLayout) rowView;
if (position == selectedItem){
ActiveItem.setBackgroundResource(R.drawable.background_dark_blue);
// for focus on it
int top = (ActiveItem == null) ? 0 : ActiveItem.getTop();
((ListView) parent).setSelectionFromTop(position, top);
}
else{
ActiveItem.setBackgroundResource(R.drawable.border02);
}
}
private int selectedItem;
public void setSelectedItem(int position) {
selectedItem = position;
}
}
In your Activity:
myAdapter.setSelectedItem(1);
I am using an Adapter and didn't want to set custom background colors, but use the android:state_selected in drawable xml. SetSelection didn't work for me, but maybe that's also since I needed SetNotifyDataChanged which shows that the Selected State is not persistent.
I also found that the Selected state for an item in a ListView is not persistent, since SetNotifyDataChanged results in updating the ListView layout which clears them all. Setting the item to Selected in the Adapter's GetView is too soon too.
Eventually I set the Selected state for the view of the selected item after the layout of the listview has been changed, which is when LayoutChange event is being triggered (in Java it's probably attaching a to OnLayoutChangeListener of the ListView).
To make it really easy I store the view of the selected item as Adapter's SelectedItemView.
In the ListView's LayoutChange eventhandler I just set the adapter's SelectedItemView.Selected to true.
Here's the code from my Activity where I set the Adapter for the ListView and also subscribe to LayoutChange (or in Java attach an OnLayoutChangeListener)
ringTonesListView.Adapter = ringTonesListAdapter;
ringTonesListView.LayoutChange += (s, layoutChangeArgs) => {
//At this stage the layout has been updated and the Selected can be set to true for the view of the selected item. This will result in android:state_selected logic to be applied as desired and styling can be completely done per layout in Resources.
ringTonesListAdapter.SelectedItemView.Selected = true;
};
Here's my code for the Adapter:
public class RingTonesListAdapter : BaseAdapter<RingToneItem>
{
List<RingTone> Items { get; set; }
public override View GetView(int position, View convertView, ViewGroup parent)
{
View view = convertView;
// re-use an existing view, if one is available
// otherwise create a new one
if (view == null)
{
view = Context.LayoutInflater.Inflate(Resource.Layout.AlertSoundItem, parent, false);
view.Click += SelectRingTone;
}
RingTone ringTone = this[position];
if (ringTone.Selected)
{
//==> Important
//Store this view since it's the view for the Selected Item
SelectedItemView = view;
//Setting view.Selected to true here doesn't help either, since Selected will be cleared after.
}
return view;
}
private void SelectRingTone(object sender, EventArgs args)
{
View view = (View)sender;
string title = view.FindViewById<TextView>(Resource.Id.ringToneTitle).Text;
RingToneItem ringToneItem = Items.First(rt => rt.Title == title);
if (!ringToneItem.Selected)
{
//The RingTone was not selected and is selected now
//Deselect Old and Select new
foreach (RingToneItem oldItem in Items.Where(rt => rt.Selected))
{
oldItem.Selected = false;
}
// Select New RingTone
ringToneItem.Selected = true;
//Update the ListView.
//This will result in removal of Selected state for all Items when the ListView updates it's layout
NotifyDataSetChanged();
}
//Now play the test sound
NotifierService.TestSound(Context, ringToneItem);
}
public View SelectedItemView { get; set; }
}