adapter calls methods in fragment s

Okay, let's start to solve this problem:

After checking it on the internet, no corresponding solution has been found. The gods say there are two ways:

• Interface callback
• Radio broadcast

I use local broadcasting to achieve the above problems. The specific implementation is as follows:

1. First, create a new adapter inherited from RecyclerView.Adapter, the specific code is as follows:

   public class ProvinceCityAdapter extends
           RecyclerView.Adapter<ProvinceCityAdapter.ViewHolder> {
   
       private static final String TAG = "ProvinceCityAdapter";
   
   
       private List<String> mDataList = new ArrayList<>();   //data
   
       private LocalBroadcastManager localBroadcastManager;
   
       //Used for caching data
       static class ViewHolder extends RecyclerView.ViewHolder {
   
           TextView textView;
   
           //Construction method
           public ViewHolder(View itemView) {
               super(itemView);
               textView = (TextView) itemView.findViewById(R.id.tv_prcico);
           }
       }
   
       public ProvinceCityAdapter(List<String> mDataList) {
           this.mDataList = mDataList;
       }
   
       //Create a ViewHolder instance
       @Override
       public ViewHolder onCreateViewHolder(final ViewGroup parent, int viewType) {
           final View view = LayoutInflater.from(parent.getContext()).
                   inflate(R.layout.item_prcico_layout, parent, false);
           final ViewHolder viewHolder = new ViewHolder(view);
           localBroadcastManager = LocalBroadcastManager.getInstance(parent.getContext());
           final Intent intent = new Intent(ChooseAreaFragment.LOCAL_BROADCAST);
           viewHolder.textView.setOnClickListener(new View.OnClickListener() {
               @Override
               public void onClick(View v) {
                   int adapterPosition = viewHolder.getAdapterPosition();  //An index of clicks is available
                   intent.putExtra("query_city", true);   //Notify fragment to call the queryCity() method
                   localBroadcastManager.sendBroadcast(intent);   //Send local broadcast notification fragment to refresh
               }
           });
           return viewHolder;
       }
   
       //Subitem data assignment is performed when scrolled to the screen
       @Override
       public void onBindViewHolder(ViewHolder holder, int position) {
           String position_choice = mDataList.get(position);
           holder.textView.setText(position_choice);
       }
   
       //How many subitems are there?
       @Override
       public int getItemCount() {
           return mDataList.size();
       }
   
   }
   

2. Then write a fragment code that needs to register local broadcasts. When receiving the broadcast sent by adapter, it needs to react. The specific implementation is as follows:

       public class ChooseAreaFragment extends Fragment {
   
           private static final String TAG = "ChooseAreaFragment";
   
   
           private RecyclerView recyclerView;  //list
           private ProvinceCityAdapter adapter;  //Adapter
           private List<String> dataList = new ArrayList<>();   //data
   
   
   
           private IntentFilter intentFilter;
           private LocalReceiver localReceiver;    //Local Broadcast Receiver
           private LocalBroadcastManager localBroadcastManager;   //Local broadcasting administrators can be used to register broadcasts
   
           /**
            * Actions to send local broadcasts
            */
           public static final String LOCAL_BROADCAST = "com.xfhy.casualweather.LOCAL_BROADCAST";
   
           //Do some initialization
           @Nullable
           @Override
           public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
               View view = inflater.inflate(R.layout.choose_area, container, false);
               recyclerView = (RecyclerView)view.findViewById(R.id.recycler_view);
   
               //Get the Local Broadcast Manager Local Broadcast Manager instance
               localBroadcastManager = LocalBroadcastManager.getInstance(getContext());
               localReceiver = new LocalReceiver();
               intentFilter = new IntentFilter();
               intentFilter.addAction(LOCAL_BROADCAST);   //Add action
               localBroadcastManager.registerReceiver(localReceiver,intentFilter);   //Register Local Broadcasting
   
               //Setting up LayoutManager
               LinearLayoutManager linearManager = new LinearLayoutManager(getContext());
               recyclerView.setLayoutManager(linearManager);
   
   
               //Setting up adapter
               adapter = new ProvinceCityAdapter(dataList);
               recyclerView.setAdapter(adapter);
   
               return view;
           }
   
           @Override
           public void onActivityCreated(@Nullable Bundle savedInstanceState) {
               super.onActivityCreated(savedInstanceState);
           }
   
           /**
            * Queries select all cities in the province, first query from the database, if there is no query to the server.
            */
           protected void queryCities() {
               Log.i(TAG, "queryCities: I am queryCities");
           }
   
   
           private class LocalReceiver extends BroadcastReceiver{
               @Override
               public void onReceive(Context context, Intent intent) {
                   String action = intent.getAction();
                   if(!action.equals(LOCAL_BROADCAST)){
                       return ;
                   }
   
                   boolean queryCity = intent.getBooleanExtra("query_city",false);  //Determine whether a query city needs to be invoked
   
                   //If it receives broadcasts that need to query city information, it executes the method.
                   if(queryCity){
                       queryCities();
                   }
   
               }
           }
   
           @Override
           public void onDestroy() {
               super.onDestroy();
               localBroadcastManager.unregisterReceiver(localReceiver);    //Cancellation of broadcasting registration
           }
   }
   

Summary: When adapter calls the method in fragment, it actually registers local broadcasting in fragment, and then when adapter needs to call the method in fragment, it sends a broadcasting to adapter itself. Then fragment receives the broadcasting, analyses the data, knows what method to call, and finally calls the method in fragment itself. It's easy to implement.