android: 无法从 RecyclerView.ViewHolder 加载新 Activity

Question

我可以在 onClick 事件中显示一个 Toast 但无法加载新的 Activity。

这是我的代码:

public class AppointmentAdapter extends RecyclerView.Adapter<AppointmentAdapter.MyViewHolder> {

    private ArrayList<Appointment> appointmentList;
    private Context mContext;

    public AppointmentAdapter(Context context) {
        mContext = context;
    }

    public class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

        public Button mView, mSend;

        public MyViewHolder(View view) {
            super(view);
            mView = (Button) view.findViewById(R.id.button_view_appointment);
            mSend = (Button) view.findViewById(R.id.button_send_appointment);

            mView.setOnClickListener(this);
            mSend.setOnClickListener(this);
        }

        @Override
        public void onClick(View v) {

            if (v.getId() == mView.getId()) {
         //       Toast.makeText(v.getContext(), "View ITEM PRESSED = " + String.valueOf(getAdapterPosition()), Toast.LENGTH_SHORT).show();

                Intent detailsIntent = new Intent(mContext, DetailsActivity.class);
                mContext.startActivity(detailsIntent);
            }

            if (v.getId() == mSend.getId()) {
      //          Toast.makeText(v.getContext(), "Send ITEM PRESSED = " + String.valueOf(getAdapterPosition()), Toast.LENGTH_SHORT).show();
            }
        }
    }
    /................./
}

这行特定的代码不起作用。

Intent detailsIntent = new Intent(mContext, DetailsActivity.class);
        mContext.startActivity(detailsIntent);
    }

当我运行这个应用程序时得到了 NullPointException 请帮忙。提前致谢

Answer 1

您的 mContext 变量是 null。您需要检查您的代码以了解为什么此变量为 null。

既然您说过可以显示 Toast，请使用 v.getContext()。要传递数据，请使用 getAdapterPosition() 获取点击的项目并在 Intent 中传递数据。确保 Appointment 类实现了 Serializable 接口(interface)。

Appointment selectedAppointment = appointmentList.get(getAdapterPosition());
Intent detailsIntent = new Intent(v.getContext(), DetailsActivity.class);
detailsIntent.putExtra("selectedAppointment", selectedAppointment);
v.getContext().startActivity(detailsIntent);