领域数据库更新时如何更新recycleview单个项目？

Question

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

Context c;
ArrayList<MarketObject> marketObject;
public RecyclerView recyclerView;

public MyAdapterMarket(MarketActivity.MyFragment c, ArrayList<MarketObject> marketObject)  {
    this.marketObject = marketObject;
}

// I AM ABLE TO GET UPDATED OBJECT HERE BUT HOW CAN I UPDATE IN RECYCLEVIEW AT PARTICULAR POSITION. // marketObject.getLast() gives updated value in Realm Database
public static void updateEmployeeListItems(MarketObject marketObject) {
    Log.e("UPDATED OBJECT FROM REALM DATABASE",""+marketObject.getLast());
    }

@Override
public MyAdapterMarket.MyViewHolder onCreateViewHolder(final ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.calender_market_list, parent, false);
    return new MyAdapterMarket.MyViewHolder(v);
}

public class MyViewHolder extends RecyclerView.ViewHolder {
    public TextView market_title, country_name, market_last, market_time, market_dailyPercentageChange, market_dailyChange;
    public LinearLayout actual, previous, constant;

    public MyViewHolder(View itemView) {
        super(itemView);

        c = itemView.getContext();
        recyclerView = (RecyclerView) itemView.findViewById(R.id.calendar_fragment_recycleview);
        market_title = (TextView) itemView.findViewById(R.id.market_title);
        country_name = (TextView) itemView.findViewById(R.id.country_name);
        market_last = (TextView) itemView.findViewById(R.id.market_last);
        market_time = (TextView) itemView.findViewById(R.id.market_time);
        market_dailyPercentageChange = (TextView) itemView.findViewById(R.id.market_dailyPercentageChange);
        market_dailyChange = (TextView) itemView.findViewById(R.id.market_dailyChange);

    }
}

@Override
public void onBindViewHolder(MyAdapterMarket.MyViewHolder holder, final int position) {
    final MarketObject market = marketObject.get(position);


    holder.market_title.setText(market.getName());
    holder.country_name.setText(capitalize(market.getCountry()));
    holder.market_last.setText(market.getLast());
    holder.market_time.setText(market.getTime());
    holder.market_dailyPercentageChange.setText(market.getDailypercentualchange());
    holder.market_dailyChange.setText(market.getDailychange());

    holder.itemView.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            //Log.v("RECYCLEVIEW POSITION", "Element " + getAdapterPosition() + " clicked.");
            AutoUpdate(position, "0.007");
            Context context = v.getContext();
            Intent intent = new Intent(context, MarketDetail.class);
            intent.putExtra( "NAME" , market.getName());
            //context.startActivity(intent);
        }
    });
}

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

给代码是我的适配器代码，现在我正在获取市场的实时数据，该数据可以通过MarketObject在Realm数据库中完美更新。 我想用动画在Recycleview中反映该数据，以便用户可以看到该市场价格已更新。 怎么可能。 在Realm数据库中更新此值时，我在此函数“ updateEmployeeListItems（）”中传递对象。 现在，我无法在RecycleView中的特定位置进行更新。

在下面的图像中，当我从服务器获取更新时，我正在更新Realm数据库中的数据，正如我在“ updateEmployeeListItems（）”中所述，我正在从中获取更新的对象，现在我想在RecycleView中更新此对象数据

Answer 1

好的，如果您想利用Realm的细粒度通知，则应该使用RealmRecyclerViewAdapter ，并且在此之上

public class MyAdapterMarket extends RealmRecyclerViewAdapter<MarketObject, MyAdapterMarket.MyViewHolder> {
    public MyAdapterMarket(OrderedRealmCollection<MarketObject> results  {
        super(results, true, false); // passing `false` to handle `change` manually
    }

    @Override
    public MyAdapterMarket.MyViewHolder onCreateViewHolder(final ViewGroup parent, int viewType) {
        return new MyAdapterMarket.MyViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.calender_market_list, parent, false));
    }

    public class MyViewHolder extends RecyclerView.ViewHolder {
        Context c;
        RecyclerView recyclerView;

        TextView market_title, country_name, market_last, market_time, market_dailyPercentageChange, market_dailyChange;
        LinearLayout actual, previous, constant;

        public MyViewHolder(View itemView) {
            super(itemView);

            c = itemView.getContext();
            recyclerView = (RecyclerView) itemView.findViewById(R.id.calendar_fragment_recycleview);
            market_title = (TextView) itemView.findViewById(R.id.market_title);
            country_name = (TextView) itemView.findViewById(R.id.country_name);
            market_last = (TextView) itemView.findViewById(R.id.market_last);
            market_time = (TextView) itemView.findViewById(R.id.market_time);
            market_dailyPercentageChange = (TextView) itemView.findViewById(R.id.market_dailyPercentageChange);
            market_dailyChange = (TextView) itemView.findViewById(R.id.market_dailyChange);
        }

        RealmObjectChangeListener realmChangeListener = new RealmObjectChangeListener<MarketObject>() {
             @Override
             public void onChange(MarketObject market, ObjectChangeSet changeSet) {
                if(changeSet.isDeleted()) return;

                if(changeSet.isFieldChanged("name")) {
                    market_title.setText(market.getName());
                } 
                if(changeSet.isFieldChanged("country")) {
                    country_name.setText(capitalize(market.getCountry()));
                }
                if(changeSet.isFieldChanged("last")) {
                    market_last.setText(market.getLast());
                }
                if(changeSet.isFieldChanged("time")) {
                    market_time.setText(market.getTime());
                }
                if(changeSet.isFieldChanged("dailypercentualchange")) {
                     market_dailyPercentageChange.setText(market.getDailypercentualchange());
                }
                if(changeSet.isFieldChanged("dailychange")) {
                    market_dailyChange.setText(market.getDailychange());
                }
             }
        }

        MarketObject market;

        public void bind(MarketObject market) {        
            if(this.market != null && this.market.isValid()) {
                this.market.removeAllChangeListeners();
            }
            this.market = market;
            market.addChangeListener(realmChangeListener);
            market_title.setText(market.getName());
            country_name.setText(capitalize(market.getCountry()));
            market_last.setText(market.getLast());
            market_time.setText(market.getTime());

            market_dailyPercentageChange.setText(market.getDailypercentualchange());
            market_dailyChange.setText(market.getDailychange());

            itemView.setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View v) {
                    //Log.v("RECYCLEVIEW POSITION", "Element " + getAdapterPosition() + " clicked.");
                    AutoUpdate(position, "0.007");
                    Context context = v.getContext();
                    Intent intent = new Intent(context, MarketDetail.class);
                    intent.putExtra( "NAME" , market.getName());
                    //context.startActivity(intent);
                }
            });
        }
    }

    @Override
    public void onBindViewHolder(MyAdapterMarket.MyViewHolder holder, final int position) {
        final MarketObject market = marketObject.get(position);
        holder.bind(market);
    }

}

Answer 2

如果您仅更新一项，则可以用新项更新后备列表（即用旧项的索引替换它），然后通过调用recyclerView.getAdapter().notifyItemChanged(POSITION)告知RecyclerView适配器有关更改的信息，其中POSITION是列表/数组中已更新项的整数索引。

如果您获得了一个完整的新项目列表 ，则可以使用DiffUtil查找旧的后备项目列表和更新的后备项目列表之间的差异，然后将这些更改分派给RecyclerView adatper：

---

话虽如此，用户@Saran Sankaran的使用RealmRecyclerViewAdapter的建议可能正是您要寻找的。 如果使用它，则无需自己执行任何notifyItemChanged逻辑。