Single selection in RecyclerView

Question

I know there are no default selection methods in recyclerview class  But I have tried in following way   public void onBindViewHolder ViewHolder holder  final int position        holder mTextView setText fonts get position  getName         holder checkBox setChecked fonts get position  isSelected          holder checkBox setOnCheckedChangeListener new CompoundButton OnCheckedChangeListener              Override         public void onCheckedChanged CompoundButton buttonView  boolean isChecked                if isChecked                    for  int i   0  i  lt  fonts size    i                          fonts get i  setSelected false                                     fonts get position  setSelected isChecked                                       While trying this code  I got expected output  But completely not    I will explain this with images    By default  the first item is selected from my adapter    Then I am trying to select 2nd and then 3rd  and then 4th and finally 5th one     Here 5th only should be selected  but all five are getting selected   If I scroll the list to bottom and come again to top     I got what I expected   How can I overcome this issue  And some time If I scroll the list very fast some other item gets selected  How to overcome this problem too   Update  While I am trying to use notifyDataSetChanged   after fonts get position  setSelected isChecked   I got following exception   java lang IllegalStateException  Cannot call this method while RecyclerView is computing a layout or scrolling         at android support v7 widget RecyclerView assertNotInLayoutOrScroll RecyclerView java 1462          at android support v7 widget RecyclerView RecyclerViewDataObserver onChanged RecyclerView java 2982          at android support v7 widget RecyclerView AdapterDataObservable notifyChanged RecyclerView java 7493          at android support v7 widget RecyclerView Adapter notifyDataSetChanged RecyclerView java 4338          at com app myapp screens RecycleAdapter onRowSelect RecycleAdapter java 111

User · Answer

You need to clear the OnCheckedChangeListener before setting setChecked      Override public void onBindViewHolder final ViewHolder holder  int position         holder mRadioButton setOnCheckedChangeListener null       holder mRadioButton setChecked position    mCheckedPosition       holder mRadioButton setOnCheckedChangeListener new CompoundButton OnCheckedChangeListener              Override         public void onCheckedChanged CompoundButton buttonView  boolean isChecked                 mCheckedPosition   position              notifyDataSetChanged                          This way it won t trigger the java lang IllegalStateException  Cannot call this method while RecyclerView is computing a layout or scrolling error

User · Answer

I want to share the similar thing I have achieved  may be it will help someone  below code is from the application to select an address from a list of addresses that are displayed in cardview cvAddress   so that on click of particular item cardview  the imageView inside the item should set to different resource select unselect          Override public void onBindViewHolder final AddressHolder holder  final int position        holderList add holder       holder tvAddress setText addresses get position  getAddress         holder cvAddress setOnClickListener new View OnClickListener              Override         public void onClick View view                selectCurrItem position                        private void selectCurrItem int position        int size   holderList size        for int i   0  i lt size  i                  if i  position              holderList get i  ivSelect setImageResource R drawable select           else             holderList get i  ivSelect setImageResource R drawable unselect             I don t know this is best solution or not but this worked for me

User · Answer

This simple one worked for me  private RadioButton lastCheckedRB   null       Override public void onBindViewHolder final CoachListViewHolder holder  final int position      holder priceRadioGroup setOnCheckedChangeListener new RadioGroup OnCheckedChangeListener          Override     public void onCheckedChanged RadioGroup group  int checkedId            RadioButton checked rb    RadioButton  group findViewById checkedId           if  lastCheckedRB    null  amp  amp  lastCheckedRB    checked rb                lastCheckedRB setChecked false                       store the clicked radiobutton         lastCheckedRB   checked rb

User · Answer

Please try this    This works for me    In adapter take a sparse boolean array   SparseBooleanArray sparseBooleanArray    In constructor initialise this      sparseBooleanArray new SparseBooleanArray      In bind holder add    Override public void onBindViewHolder DispositionViewHolder holder  final int position       holder tv disposition setText dispList get position  getName         if sparseBooleanArray get position false                 holder rd disp setChecked true             else               holder rd disp setChecked false               setClickListner holder position      private void setClickListner final DispositionViewHolder holder  final int position        holder rd disp setOnClickListener new View OnClickListener              Override         public void onClick View v                sparseBooleanArray clear                sparseBooleanArray put position  true               notifyDataSetChanged                            rd disp is radio button in xml file   So when the recycler view load the items in bindView Holder it check whether the sparseBooleanArray contain the value  true  correspnding to its position   If the value returned is true then we set the radio button selection true Else  we set the selection false  In onclickHolder I have cleared the sparseArray and set the value true corresponding to that position  When I call notify datasetChange it again call the onBindViewHolder and the condition are checked again  This makes our selection to only select particular radio

User · Answer

This might help for those who want a single radiobutton to work --   Radio Button RecycleView - Gist  If lambda expressions aren t supported  use this instead   View OnClickListener listener   new View OnClickListener          Override     public void onClick View v            notifyItemChanged mSelectedItem      to update last selected item          mSelectedItem   getAdapterPosition               Cheers

User · Answer

Looks like there are two things at play here      1  The views are reused  so the old listener is still present    2  You are changing the data without notifying the adapter of the change   I will address each separately    1  View reuse  Basically  in onBindViewHolder you are given an already initialized ViewHolder  which already contains a view   That ViewHolder may or may not have been previously bound to some data   Note this bit of code right here   holder checkBox setChecked fonts get position  isSelected       If the holder has been previously bound  then the checkbox already has a listener for when the checked state changes  That listener is being triggered at this point  which is what was causing your IllegalStateException     An easy solution would be to remove the listener before calling setChecked   An elegant solution would require more knowledge of your views - I encourage you to look for a nicer way of handling this    2  Notify the adapter when data changes  The listener in your code is changing the state of the data without notifying the adapter of any subsequent changes   I don t know how your views are working so this may or may not be an issue   Typically when the state of your data changes  you need to let the adapter know about it   RecyclerView Adapter has many options to choose from  including notifyItemChanged  which tells it that a particular item has changed state   This might be good for your use   if isChecked        for  int i   0  i  lt  fonts size    i              if  i    position  continue          Font f   fonts get i           if  f isSelected                  f setSelected false               notifyItemChanged i      Tell the adapter this item is updated                     fonts get position  setSelected isChecked       notifyItemChanged position

User · Answer

This is how its looks    Inside your Adapter  private int selectedPosition   -1    And onBindViewHolder   Override public void onBindViewHolder  NonNull MyViewHolder holder  int position         if  selectedPosition    position            holder itemView setSelected true     using selector drawable         holder tvText setTextColor ContextCompat getColor holder tvText getContext   R color white          else           holder itemView setSelected false           holder tvText setTextColor ContextCompat getColor holder tvText getContext   R color black               holder itemView setOnClickListener v - gt            if  selectedPosition  gt   0              notifyItemChanged selectedPosition           selectedPosition   holder getAdapterPosition            notifyItemChanged selectedPosition               Thats it   As you can see i am just Notifying updating  previous selected item and newly selected item  My Drawable set it as a background for recyclerview child views   lt selector xmlns android  http   schemas android com apk res android  gt   lt item android state focused  false  android state selected  true  gt       lt shape android shape  rectangle  gt           lt solid android color   color blue    gt       lt  shape gt   lt  item gt

User · Answer

just use mCheckedPosition save status   Override         public void onBindViewHolder ViewHolder holder  int position                 holder checkBox setChecked position    mCheckedPostion               holder checkBox setOnClickListener v - gt                    if  position    mCheckedPostion                        holder checkBox setChecked false                       mCheckedPostion   -1                    else                       mCheckedPostion   position                      notifyDataSetChanged

User · Answer

This is how the Adapter class looks like     public class MyRecyclerViewAdapter extends RecyclerView Adapter lt MyRecyclerViewHolder gt    Context context  ArrayList lt RouteDetailsFromFirestore gt  routeDetailsFromFirestoreArrayList   public int  lastSelectedPosition -1    public MyRecyclerViewAdapter Context context  ArrayList lt RouteDetailsFromFirestore gt  routeDetailsFromFirestoreArrayList        this context   context      this routeDetailsFromFirestoreArrayList    routeDetailsFromFirestoreArrayList      NonNull  Override public MyRecyclerViewHolder onCreateViewHolder  NonNull ViewGroup viewGroup  int i           LayoutInflater layoutInflater   LayoutInflater from mainActivity  getBaseContext         LayoutInflater layoutInflater   LayoutInflater from viewGroup getContext         View view   layoutInflater inflate R layout route details  viewGroup  false       return new MyRecyclerViewHolder view       Override public void onBindViewHolder  NonNull final MyRecyclerViewHolder myRecyclerViewHolder  final int i            This is the part where the appropriate checking and unchecking of radio button happens appropriately        myRecyclerViewHolder mRadioButton setOnCheckedChangeListener new CompoundButton OnCheckedChangeListener              Override         public void onCheckedChanged CompoundButton compoundButton  boolean b                if b                    if  lastSelectedPosition    -1            Getting the reference to the previously checked radio button and then unchecking it lastSelectedPosition has the index of the previously selected radioButton                            RadioButton rb    RadioButton    MainActivity  context  linearLayoutManager getChildAt lastSelectedPosition  findViewById R id rbRadioButton                       RadioButton rb    RadioButton    MainActivity  myRecyclerViewHolder mRadioButton getContext    linearLayoutManager getChildAt lastSelectedPosition  findViewById R id rbRadioButton                       rb setChecked false                                         lastSelectedPosition   i                         Checking the currently selected radio button                        myRecyclerViewHolder mRadioButton setChecked true                                           Override public int getItemCount         return routeDetailsFromFirestoreArrayList  size           End of Adapter Class   Inside MainActivity java we call the ctor of Adapter class like this  The context passed is of MainActivity to the Adapter ctor      myRecyclerViewAdapter   new MyRecyclerViewAdapter MainActivity this  routeDetailsList

User · Answer

This happens because RecyclerView  as the name suggests  does a good job at recycling its ViewHolders  This means that every ViewHolder  when it goes out of sight  actually  it takes a little more than going out of sight  but it makes sense to simplify it that way   it is recycled  this implies that the RecyclerView takes this ViewHolder that is already inflated and replaces its elements with the elements of another item in your data set   Now  what is going on here is that once you scroll down and your first  selected  ViewHolders go out of sight  they are being recycled and used for other positions of your data set  Once you go up again  the ViewHolders that were bound to the first 5 items are not necessarely the same  now   This is why you should keep an internal variable in your adapter that remembers the selection state of each item  This way  in the onBindViewHolder method  you can know if the item whose ViewHolder is currently being bound was selected or not  and modify a View accordingly  in this case your RadioButton s state  though I would suggest to use a CheckBox if you plan on selecting multiple items    If you want to learn more about RecyclerView and its inner workings  I invite you to check FancyAdapters  a project I started on GitHub  It is a collection of adapters that implement selection  drag amp drop of elements and swipe to dismiss capabilities  Maybe by checking the code you can obtain a good understanding on how RecyclerView works

User · Answer

The following might be helpful for RecyclerView with Single Choice   Three steps to do that  1  Declare a global integer variable   private int mSelectedItem   -1    2  in onBindViewHolder   mRadio setChecked position    mSelectedItem     3  in onClickListener  mSelectedItem   getAdapterPosition    notifyItemRangeChanged 0  mSingleCheckList size     mAdapter onItemHolderClick SingleCheckViewHolder this

User · Answer

The solution for the issue   public class yourRecyclerViewAdapter extends RecyclerView Adapter lt yourRecyclerViewAdapter yourViewHolder gt     private static CheckBox lastChecked   null  private static int lastCheckedPos   0    public void onBindViewHolder ViewHolder holder  final int position         holder mTextView setText fonts get position  getName         holder checkBox setChecked fonts get position  isSelected         holder checkBox setTag new Integer position           for default check in first item     if position    0  amp  amp  fonts get 0  isSelected    amp  amp  holder checkBox isChecked                 lastChecked   holder checkBox         lastCheckedPos   0             holder checkBox setOnClickListener new View OnClickListener                   Override         public void onClick View v                        CheckBox cb    CheckBox v             int clickedPos     Integer cb getTag    intValue                 if cb isChecked                               if lastChecked    null                                    lastChecked setChecked false                     fonts get lastCheckedPos  setSelected false                                                         lastChecked   cb                lastCheckedPos   clickedPos                        else              lastChecked   null             fonts get clickedPos  setSelected cb isChecked                         Hope this help

User · Answer

So  after spending so many days over this  this is what I came up with which worked for me  and is good practice as well    Create an interface  name it some listener  SomeSelectedListener   Add a method which takes an integer void onSelect int position   Initialise the listener in the recycler adapter s constructor as   a  first declare globally as  private SomeSelectedListener listener b  then in constructor initialise as  this listener   listener  Inside onClick   of checkbox inside onBindViewHolder    update the method of the interface listener by passing the position as  listener onSelect position  In the model  add a variable for deselect say  mSelectedConstant and initialise it there to 0  This represents the default state when nothing is selected  Add getter and setter for the mSelectedConstant in the same model  Now  go to your fragment activity and implement the listener interface  Then override its method  onSelect int position   Within this method  iterate through your list which you are passing to your adapter using a for loop and setSelectedConstant to 0 for all      code    Override public void onTicketSelect int position    for  ListType listName   list        listName setmSelectedConstant 0       8  Outside this  make the selected position constant 1    code  list get position  setmSelectedConstant 1      Notify this change by calling  adapter notifyDataSetChanged    immediately after this  Last step  go back to your adapter and update inside onBindViewHolder   after onClick   add the code to update the checkbox state     code       if  listVarInAdapter get position  getmSelectedConstant      1        holder checkIcon setChecked true       selectedTicketType   dataSetList get position     else       commonHolder checkCircularIcon setChecked false

User · Answer

It s quite late  but I m still posting it as it may help someone else   Use the code below as a reference to check a single item in RecyclerView          Created by subrahmanyam on 28-01-2016  04 02 PM      public class SampleAdapter extends RecyclerView Adapter lt SampleAdapter ViewHolder gt         private final String   list      private int lastCheckedPosition   -1       public SampleAdapter String   list            this list   list              Override     public ViewHolder onCreateViewHolder ViewGroup parent  int viewType            View view   View inflate parent getContext    R layout sample layout  null           ViewHolder holder   new ViewHolder view           return holder              Override     public void onBindViewHolder ViewHolder holder  int position            holder choiceName setText list position            holder radioButton setChecked position    lastCheckedPosition               Override     public int getItemCount             return list length             public class ViewHolder extends RecyclerView ViewHolder            Bind R id choice name          TextView choiceName           Bind R id choice select          RadioButton radioButton           public ViewHolder View itemView                super itemView               ButterKnife bind this  itemView               radioButton setOnClickListener new View OnClickListener                      Override                 public void onClick View v                        int copyOfLastCheckedPosition   lastCheckedPosition              lastCheckedPosition   getAdapterPosition                notifyItemChanged copyOfLastCheckedPosition               notifyItemChanged lastCheckedPosition

User · Answer

public class GetStudentAdapter extends              RecyclerView Adapter lt GetStudentAdapter MyViewHolder gt                 private List lt GetStudentModel gt  getStudentList              Context context              RecyclerView recyclerView               public class MyViewHolder extends RecyclerView ViewHolder                   TextView textStudentName                  RadioButton rbSelect                   public MyViewHolder View view                        super view                       textStudentName    TextView  view findViewById R id textStudentName                       rbSelect    RadioButton  view findViewById R id rbSelect                                                  public GetStudentAdapter Context context  RecyclerView recyclerView  List lt GetStudentModel gt  getStudentList                    this getStudentList   getStudentList                  this recyclerView   recyclerView                  this context   context                              Override             public MyViewHolder onCreateViewHolder ViewGroup parent  int viewType                    View itemView   LayoutInflater from parent getContext                             inflate R layout select student list item  parent  false                   return new MyViewHolder itemView                               Override             public void onBindViewHolder final MyViewHolder holder  final int position                    holder textStudentName setText getStudentList get position  getName                     holder rbSelect setChecked getStudentList get position  isSelected                     holder rbSelect setTag position      This line is important                  holder rbSelect setOnClickListener onStateChangedListener holder rbSelect  position                                 Override             public int getItemCount                     return getStudentList size                              private View OnClickListener onStateChangedListener final RadioButton checkBox  final int position                    return new View OnClickListener                          Override                     public void onClick View v                            if  checkBox isChecked                                  for  int i   0  i  lt  getStudentList size    i                                       getStudentList get i  setSelected false                                                              getStudentList get position  setSelected checkBox isChecked                                  notifyDataSetChanged                              else

[android] Single selection in RecyclerView

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