即使在数组列表和adapter.notifyDataSetChanged()中添加数据后，回收器视图也不会显示

Question

有一个 RecyclerView

suggestList

，单击其中的任何

itemView

时，我们会得到适配器位置（），它已通过一个函数从用于

suggestList adapter

的 ArrayList 中获取值。现在，我在

StockPrice()

中创建了一个函数

MainActivity

，单击 itemView 时也会调用该函数，并且在 arrayList

stockPriceList

中，我们保存 itemView 从

suggestList

recyclerView 传递的数据。

stockPriceList

用于另一个recyclerView，一切都已设置，但是当我添加传递的数据

(from suggestList recyclerView)

并调用用于第二个recyclerView的

stockPriceAdapter.notifyDataSetChanged()

时，它没有在RecyclerView中显示任何数据。

建议列表适配器：

 public class ViewHolder extends RecyclerView.ViewHolder {

    TextView symbol, name, exchange, type;
    public ConstraintLayout listContainer;
    public ViewHolder(@NonNull View itemView) {
        super(itemView);

        name = itemView.findViewById(R.id.name);
        symbol = itemView.findViewById(R.id.symbol);
        exchange = itemView.findViewById(R.id.exchange);
        type = itemView.findViewById(R.id.type);
        listContainer = itemView.findViewById(R.id.search_item_views);

        itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                MainActivity mainActivity = new MainActivity();
                stockModelClass positionedStock =  stockModelClassArrayList.get(getAbsoluteAdapterPosition());
                mainActivity.OnClickItemViewListener(positionedStock.getName(), positionedStock.getSymbol());
               // Run this one
                mainActivity.StockPrice();

                stockModelClassArrayList.clear();
                notifyDataSetChanged();
            }
        });

    }
}

MainActivity，其中我们有 StockPrice 函数。

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    suggestList = findViewById(R.id.suggestList);
    searchBar = findViewById(R.id.searchBar);
    stockModelClassesArray = new ArrayList<>();

    requestQueue = Volley.newRequestQueue(MainActivity.this);

    suggestList.setLayoutManager(new LinearLayoutManager(this));

    suggestAdapter = new stockSuggestAdapter(stockModelClassesArray, MainActivity.this);

    suggestList.setAdapter(suggestAdapter);

    searchBar.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {

        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            loadStockApi();
        }

        @Override
        public void afterTextChanged(Editable s) {

        }
    });

    // Setting up Main Activity ArrayList.
    mainWatchList = findViewById(R.id.defaultWatchList);
    stockPriceList = new ArrayList<>();
    mainWatchList.setLayoutManager(new LinearLayoutManager(this));
    stockPriceAdapter = new StockPriceAdapter(stockPriceList, MainActivity.this);
    mainWatchList.setAdapter(stockPriceAdapter);
}



 public void StockPrice() {

    String name = Name;
    String Symbol = symbol;
    String price = "$20";
    String ap = "7d0e928bad8b4a428b2d4d5351bd8a51";
    String url = "https://api.twelvedata.com/price?symbol=" + symbol + "&apikey=" + ap; // For accessing Price

    stockPriceList = new ArrayList<>();
    stockPriceAdapter = new StockPriceAdapter(stockPriceList, MainActivity.this);

    stockPriceList.add(new defualtWatchListModel(Name, symbol, price));
    stockPriceAdapter.notifyDataSetChanged();

}

Answer 1

出现此问题是因为

adapter

未设置为

RecyclerView

。

您已在

stockPriceAdapter

方法中将

stockPriceList

设置为

onCreate()

，但您在

stockPriceAdapter

方法中将新实例重新分配给

stockPrice()

并在该新实例上调用

notifyDataSetChanged()

方法（未设置）到 RecyclerView）。

解决方案： 您不需要在

ArrayList

方法中重新实例化

StockPriceAdapter

和

stockPrice()

，因为您已经在

onCreate()

方法中初始化了它们

更新代码：

public void StockPrice() {
    String name = Name;
    String Symbol = symbol;
    String price = "$20";
    String ap = "7d0e928bad8b4a428b2d4d5351bd8a51";
    String url = "https://api.twelvedata.com/price?symbol=" + symbol + "&apikey=" + ap;
    stockPriceList.add(new defualtWatchListModel(name, Symbol, price));
    stockPriceAdapter.notifyDataSetChanged();
}