java - Listview 只显示每行中的最后一项？

Question

我正在从 php 服务器检索对象的 JSON 数组并将其显示在 ListView 上，我能够成功地检索数据并将其存储到 Arraylist 中但是当我试图在 ListView 上显示它时，只有最后一项是显示多次。我正在使用 Volley 回调接口(interface)来存储数据，并使用 ListFragment。这是我的代码:

Server.getDataFromServer(getActivity(), "product.php", new Server.VolleyCallback() {
    @Override
    public void onSuccessResponse(JSONArray jsonArray) {
        try {
            for(int i = 0; i<jsonArray.length(); i++){
                mProduct.setId(jsonArray.getJSONObject(i).getInt("mId"));
                mProduct.setName(jsonArray.getJSONObject(i).getString("mName"));
                mProduct.setPrice(jsonArray.getJSONObject(i).getDouble("mPrice"));
                mProducts.add(mProduct);

                System.out.println(mProducts.get(i));
            }

        } catch (JSONException e) {
            e.printStackTrace();
        }
            ArrayAdapter<Product> adapter= new ArrayAdapter<>(getActivity(), R.layout.home_list_row, mProducts);
            setListAdapter(adapter);
        }
    }
);

这里是onCreateView

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_home, container, false);
    listView = (ListView)rootView.findViewById(android.R.id.list);
    return rootView;
}

android monitor

ListView

Answer 1

您只创建了一个 Product mProduct 实例

每个 setter 都会覆盖以前的值

在 mProducts 中你添加了相同的实例 3 次

for(int i = 0; i<jsonArray.length(); i++){
    mProduct.setId(jsonArray.getJSONObject(i).getInt("mId"));
    mProduct.setName(jsonArray.getJSONObject(i).getString("mName"));
    mProduct.setPrice(jsonArray.getJSONObject(i).getDouble("mPrice"));
    mProducts.add(mProduct);

    System.out.println(mProducts.get(i)); // shows you what you want, because you are in the loop
}

for(Product product: mProducts){
    System.out.println(product); // shows, what is realy in the ArrayList. it is always last value
}

你需要的是

for(int i = 0; i<jsonArray.length(); i++){
    Product product = new Product();
    product.setId(jsonArray.getJSONObject(i).getInt("mId"));
    product.setName(jsonArray.getJSONObject(i).getString("mName"));
    product.setPrice(jsonArray.getJSONObject(i).getDouble("mPrice"));
    mProducts.add(product);

    System.out.println(mProducts.get(i));
}

for(Product product: mProducts){
    System.out.println(product); // now you have all values
}