java - ListView不显示ArrayList中的数据

Question

我目前正在使用 Yummly API，它以 JSON 的形式返回食谱数据。用户输入一种成分，应用程序应该显示可以用该成分制作的食谱。到目前为止，搜索有效，我已经成功检索了食谱名称列表，我已将其添加到 ArrayList 中。

我可以在onPostExecute()方法中将ArrayList的所有内容打印到终端，所以ArrayList里面肯定有数据。但是由于某种原因它没有显示在 ListView 内!我能够访问结果页面，但我得到的只是一个空白页。

Search.java

public class Search extends Fragment {

EditText ingredient;
Activity mActivity;
ArrayList<String> pairs = new ArrayList<>();
private static final String TAG_TOTAL_MATCH = "totalMatchCount";
private static final String TAG_MATCHES = "matches";
private static final String TAG_NAME = "recipeName";

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.searchpage, container, false);

    Button btnSearch = (Button) rootView.findViewById(R.id.search_button);

    btnSearch.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            ingredient = (EditText) getView().findViewById(R.id.search_box);
            // search returns something
            new SearchRecipe().execute();
        }
    });

    return rootView;
}

    class SearchRecipe extends AsyncTask<String, String, ArrayList<String>> {

    private String search_string;
    private ProgressDialog pDialog;

    JSONParser jsonParser = new JSONParser();

    /**
     * Searching for recipes
     * */
    protected ArrayList<String> doInBackground(String... args) {


        String full_url = url_search_recipe + search_string;

        JSONObject json = jsonParser.makeHttpRequest(full_url, "GET", params);

        // check log cat for JSON response
        Log.d("Response", json.toString());

        // check for success tag
        try {
            int count = json.getInt(TAG_TOTAL_MATCH);
            JSONArray matches = json.getJSONArray(TAG_MATCHES);

            if (count > 0) {
                int i;

                //populate array with recipe
                for (i=0; i<matches.length(); i++){
                    JSONObject js = matches.getJSONObject(i);
                    String name = js.getString(TAG_NAME);
                    pairs.add(name);

                }
                // return json.getString(TAG_MESSAGE);

            } else {
                // no results found
                // Toast.makeText(mActivity.getApplicationContext(), "There were: " + count + " recipes found", Toast.LENGTH_LONG).show();
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }

        return null;
    }

    /**
     * After completing background task Dismiss the progress dialog
     * **/
    protected void onPostExecute(ArrayList<String> menu) {
        // dismiss the dialog once done
        pDialog.dismiss();
        //print recipes to terminal
        for(int j =0; j<pairs.size(); j++) {
            System.out.println(pairs.get(j));
        }
        FragmentManager fm = getActivity().getSupportFragmentManager();
        FragmentTransaction ft = fm.beginTransaction();
        ft.replace(R.id.container, new Results());
        ft.commit();
        View v = LayoutInflater.from(getActivity()).inflate(R.layout.fragment_resultspage, null);
        ListView myListView = (ListView) v.findViewById(R.id.resultsView);
        ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, pairs);
        myListView.setAdapter(arrayAdapter);

    }

}
}

结果.java

  @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        View rootView = inflater.inflate(R.layout.fragment_resultspage, container, false);
        return rootView;
    }

fragment_resultspage.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ListView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#9ad979"
        android:id="@+id/resultsView"
        android:scrollbars="vertical"
        android:choiceMode="singleChoice" />

</RelativeLayout>

我认为我错过了一些明显的东西，但我不知所措。它不显示任何内容的原因可能是什么？仅包含我的 Search.java 文件的一个 fragment ，因为它超过 200 行长，所以我只包含相关部分!

Answer 1

在结果 fragment 中执行此操作。您需要首先将从服务获取的数据传递到您的结果 fragment 。

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    View rootView = inflater.inflate(R.layout.fragment_resultspage, container, false);
    ListView myListView = (ListView) rootView.findViewById(R.id.resultsView);
    ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(getActivity(), 
                                     android.R.layout.simple_list_item_1, 
                                                               YOUR_RESULT);
    myListView.setAdapter(arrayAdapter);
    return rootView;
}