how to send data from one non activity class to another android

Question

In my android app I am using an Adapter inside another Adatper. Let's say child and parent Adapter. In parent Adapter I used onclick method on an item and instantiate the child Adapter. Now onClick on the view in child Adapter I want to send signal to parent Adapter and run a function..
This is my code:

// This is in parent layout

        holder.liker.setOnLongClickListener(new View.OnLongClickListener() {
            @Override
            public boolean onLongClick(View view) {
                holder.reaction_layout.setVisibility(View.VISIBLE);
                if(holder.cursor.getCount()>0)
                {
                    holder.show_reaction=true;
                    holder.tinyDB.putString("post_id",String.valueOf(holder.username.getTag()));
                    holder.tinyDB.putString("act_id",String.valueOf(holder.post_comment.getTag()));
                    while(holder.cursor.moveToNext())
                    {

                        holder.imageModelArrayList.add(new ReactionModel(holder.cursor.getString(1),holder.cursor.getString(3),holder.cursor.getString(2)));
                        holder.recyclerView.setAdapter(holder.adapter);  //Here i instantiate the child adapter
                    }
                }

                return true;
            }
        });

Now this is click function of child Adapter:

holder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                tinyDB.putString("image",imageModelArrayList.get(position).getImage_drawable());
                String react_id=String.valueOf(holder.title.getTag());
                String act_id=tinyDB.getString("act_id");
                String post_id=tinyDB.getString("post_id");
                NetworkController.postLikePojoClassCall(base64,Integer.parseInt(act_id),Integer.parseInt(react_id),Integer.parseInt(post_id)).enqueue(new retrofit2.Callback<PostLikePojoClass>() {
                    @Override
                    public void onResponse(Call<PostLikePojoClass> call, retrofit2.Response<PostLikePojoClass> response) {
                        if(response.isSuccessful()) {
                            System.out.println("response__  " + response.body().getSuccess());


                            }else{
                            System.out.println("response__  " + response.errorBody());
                            }
                        }


                    @Override
                    public void onFailure(Call<PostLikePojoClass> call, Throwable t) {
                        System.out.println("failure__  " + t.getMessage());

                    }
                });

            }
        });

In this click I want to send signal to parent Adapter that item has been clicked.

Answer 1

Use callback method to trigger your parent adapter

Create an interface

public interface MyInterface{
    void click();
}

Make parent Adapter implement the interface

class YourParentAdapter extends RecyclerView.Adapter<YourViewHolder> implements MyInterface

Pass your parent adapter into the child adapter through the constructor

public ChildAdapter(MyInterface myInterface){
    this.myInterface = interface;
}

Now you can use the function from parent Adapter inside the child Adapter:

myInterface.click();