Question

我需要发送ArrayList list_add到活动中，但是我不知道如何在可能的情况下与主要活动共享以便将来使用。有人可以帮助我实现此方法吗？下面有用于recyclerview的MainAdatper，其中我有一个list_add并想将其传递给主要活动，然后将其添加到

class MainAdapter extends RecyclerView.Adapter <MainAdapter.ViewHolder> {

    private static int lastCheckedPos = 0;
    ArrayList<String> list_add = new ArrayList<>();
    ArrayList<String> lista_show;
    private Context context;
    String t;    

    public MainAdapter(ArrayList<String> lista_shows, Context context) {
        lista_show = lista_shows;
    }

    @Override
    public MainAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from (parent.getContext ()).inflate (R.layout.row,parent,false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(final MainAdapter.ViewHolder holder, final int position) {

        holder.mdevice.setText (lista_show.get (position));
        holder.cardView.setOnLongClickListener (new View.OnLongClickListener () {
            @Override
            public boolean onLongClick(View v) {
                t = lista_show.get(position);
                if (list_add.contains(t)) {
                    Toast.makeText(v.getContext (), t+"Already Selected", Toast.LENGTH_SHORT).show();
                } else {
                    list_add.add(t);
                    holder.cardView.setCardBackgroundColor(Color.parseColor("#60B5EC"));
                    Toast.makeText(v.getContext (), t+"Added", Toast.LENGTH_SHORT).show();
                }
                return true;
            }
        });

        holder.cardView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                t = lista_show.get (position);
                holder.cardView.setCardBackgroundColor(Color.WHITE);
                if (! list_add.contains(t)) {
                    Toast.makeText(v.getContext (), "Long press for add", Toast.LENGTH_SHORT).show();
                } else {
                    list_add.remove(t);
                    Toast.makeText(v.getContext (), t+"Removed", Toast.LENGTH_SHORT).show();
                }
            }
        });

    }

    @Override
    public int getItemCount() {
        return lista_show.size ();
    }

    public class ViewHolder extends RecyclerView.ViewHolder {

        public TextView mdevice;
        CardView cardView;

        public ViewHolder( View itemView) {
            super (itemView);
            mdevice = itemView.findViewById (R.id.device);
            cardView = itemView.findViewById (R.id.mcardview);
        }
    }
}

Answer 1

添加回调接口：

public interface ListOwner {
  void push(ArrayList<String> list);
}

在适配器中设置引用：

private ListOwner listOwner;

public MainAdapter(ArrayList<String> lista_shows, Context context, ListOwner owner) {
  this.lista_show = lista_shows;
  this.listOwner = owner;
}

在需要时在适配器中调用它：

if (listOwner != null) {
  listOwner.push(list_add);
}

当然，请根据您的活动实施ListOwner：

public class MyActivity extends AppCompatActivity implements ListOwner {
 // all code

  // create instance of adapter:
  mAdapter = new MainAdapter(list_show, MyActivity.this, MyActivity.this);


  @Override
  public void push(ArrayList<String> list) {
     // you have the list here
  }
}

PS

您可以省略界面并将引用直接传递给Activity（示例中的MyActivity）

如何将ArrayList从适配器传递到活动？

1 个答案: