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[英]About RecyclerView.ViewHolder and RecyclerView.Adapter
[英]Update ArrayList for RecyclerView.Adapter from RecyclerView.ViewHolder?
在我的 MainActivity 我有這樣的事情:
recyclerAdapter = new RecyclerAdapter(this, arrayList);
recyclerView.setAdapter(recyclerAdapter);
為了更新我的 RecyclerView,我這樣做:(也在 MainActivity 中)
Item item = new Item();
item.setId(id);
item.setMessage(message);
arrayList.set(position, item);
recyclerAdapter.notifyItemChanged(position);
我想在每個 RecyclerView 列表項中都有一個按鈕,可以啟用/禁用當前條目。 因此我需要獲取當前的切換狀態。
我的問題是,如何從 ViewHolder 中更新 MainActivity 中的 RecyclerView? 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 Recycler.Adapter:
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;
}
}
定義一個Interface
。
public interface OnRecyclerItemToggleClickListener {
void onToggleClick(int adapterPosition);
}
在您的adapter
實現這一點。 並通過onCreateViewHolder
回調中的 setter 方法將適配器實例傳遞給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);
}
}
在您的適配器中:
@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.
}
並在單擊切換時從ViewHolder
調用此onToggleClick
方法。 您將收到對adapter
的回調,您可以在其中更新ArrayList
。 否則,您可以使用另一個類似的Interface
從適配器向Activity
提供回調。
您只需要添加一個靜態函數並使項目也成為靜態:
public static ArrayList<Items> getAreayList()
{
return items;
}
並在MainActivity
獲取此功能:
onStart()
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