Update ArrayList for RecyclerView.Adapter from RecyclerView.

Question

在我的主活动中，我有这样的东西：

recyclerAdapter = new RecyclerAdapter(this, arrayList);
recyclerView.setAdapter(recyclerAdapter);

要更新我的RecyclerView，我这样做：(在MainActivity中也是如此(

Item item = new Item();
item.setId(id);
item.setMessage(message);
arrayList.set(position, item);
recyclerAdapter.notifyItemChanged(position);

我想在每个回收器视图列表项中都有一个按钮，可以启用/禁用当前条目。因此，我需要获取当前的切换状态。

我的问题是，如何从我的 ViewHolder 中更新 MainActivity 中的回收器视图？ RecyclerView.ViewHolder：

public class SetViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{//, View.OnLongClickListener{
public ImageView toggle;
public SetViewHolder(View itemView){
super(itemView);
toggle = (ImageView) itemView.findViewById(R.id.img_main_card_toggle);
toggle.setOnClickListener(this);
}

@Override
public void onClick(View v) {
if (v.getId() == toggle.getId()) {
int clicked_position = getAdapterPosition();
//TODO update Item of RecyclerView of MainActivity
}
}

我的回收器适配器：

public class RulesAdapter extends RecyclerView.Adapter<SetViewHolder>{
private Activity activity;
List<Item> items = Collections.emptyList();
private OnTapListener onTapListener;
public RulesAdapter(Activity activity, List<Item> items){
this.activity = activity;
this.items = items;
}
@Override
public SetViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.rules_list_item,parent,false);
return new SetViewHolder(view);
}
@Override
public void onBindViewHolder(SetViewHolder holder, final int position) {
holder.recevied_message.setText(items.get(position).getReceived_message());
holder.reply_message.setText(items.get(position).getReply_message());
holder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(onTapListener != null){
onTapListener.OnTapView(position);
}
}
});
}
@Override
public int getItemCount() {
return items.size();
}
public void setOnTapListener(OnTapListener onTapListener){
this.onTapListener = onTapListener;
}

}

Answer 1

定义一个Interface。

public interface OnRecyclerItemToggleClickListener {
void onToggleClick(int adapterPosition);
}

在您的adapter中实现这一点。并通过onCreateViewHolder回调中的 setter 方法将适配器实例传递给ViewHolder。

public class SetViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{//, View.OnLongClickListener{
public ImageView toggle;
private OnRecyclerItemToggleClickListener listener;
public SetViewHolder(View itemView){
super(itemView);
toggle = (ImageView) 
itemView.findViewById(R.id.img_main_card_toggle);
toggle.setOnClickListener(this);
}

public void setRecyclerItemToggleClickListener( OnRecyclerItemToggleClickListener listener) {
this.listener = listener;
}
@Override
public void onClick(View v) {
if (v.getId() == toggle.getId()) {
int clicked_position = getAdapterPosition();

//TODO update Item of RecyclerView of MainActivity
listener.onToggleClick(clicked_position);
}
}

在适配器中：

@Override
public SetViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.rules_list_item,parent,false);
SetViewHolder holder = new SetViewHolder(view);
holder.setOnRecyclerItemToggleClickListener(this);
return holder; 
}
@Override public void onToggleClick(int adapterPosition) {
// you will get the callback here when the toggle button is clicked.
// you can update the ArrayList here.
// Or similarly, call an interface method to Activity.
}

并在单击切换开关时从ViewHolder调用此onToggleClick方法。您将获得对adapter的回调，您可以在其中更新ArrayList。否则，您可以使用另一个类似的Interface从适配器回调Activity。

Answer 2

你只需要添加一个静态函数，并使项目也成为静态的：

public static ArrayList<Items> getAreayList()
{
return items;
}

并在MainActivity中获取此函数：

onStart()