Question

正如我在标题中所说，我无法弄清楚如何从makePageRequest方法获取填充数组列表，该方法使用内部类

使用Facebook SDK迫使我使用某些方法，这些方法不允许我从方法到全局字段中获取arraylist值。

这是我在ListFragment类中的代码

public class SelectionFragment extends ListFragment {

    private static final String TAG = "SelectionFragment";
    public static final String PAGE_URL = "1438734076389483/feed";
    private static final int REAUTH_ACTIVITY_CODE = 100;

    private static final String[] FROM = { "message", "crated_time", "likes" };
    private static final int[] TO = { R.id.feed_box, R.id.created_time, R.id.like_count };

    ArrayList<HashMap<String, String>> feedsList;

    @Override
    public void onAttach(Activity activity) {
        Log.d(TAG, "onAttach method is called");
        feedsList = new ArrayList<HashMap<String,String>>();
        super.onAttach(activity);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        Log.d(TAG, "onCreateView method is called");
        //super.onCreateView(inflater, container, savedInstanceState);

        // Check for an open session
        final Session session = Session.getActiveSession();
        if (session != null && session.isOpened()) {            
            // Get the page's feed
            makePageRequest(session);
            Log.d(TAG, "makePageRequest method is called from onCreateView");
        }

        SimpleAdapter adapter = new SimpleAdapter(getActivity()
                .getBaseContext(), feedsList, R.layout.row, FROM, TO);
        setListAdapter(adapter);
        return super.onCreateView(inflater, container, savedInstanceState);
    }


    @Override
    public void onCreate(Bundle savedInstanceState) {
        Log.d(TAG, "onCreate method is called");
        super.onCreate(savedInstanceState);
        uiHelper = new UiLifecycleHelper(getActivity(), callback);
        uiHelper.onCreate(savedInstanceState);
    }

    private void makePageRequest(final Session session) {
        Log.d(TAG, "makePageRequest method is called");
        // Make an API call to get the page feed
        // and define a new callback to handle the response.
        new Request(session, PAGE_URL, null, HttpMethod.GET, new Request.Callback() {
                    public void onCompleted(Response response) {
                        if (session == Session.getActiveSession()) {
                            if (response != null) {
                                jSONToArrayList(response);
                            }
                        }
                        if (response.getError() != null) {
                            // Handle errors
                        }
                    }
                }).executeAsync();
    }

    public ArrayList<HashMap<String, String>> jSONToArrayList(
            Response facebookJSON) {
        Log.d(TAG, "jSONToArrayList method is called");     
        ArrayList<HashMap<String, String>> dataList = new ArrayList<HashMap<String, String>>();
        JSONObject jSONGraphAPI;
        JSONArray dataJSONArray;
        int likeCount = 0;
        String message = "", createdTime = "";

        try {
            jSONGraphAPI = facebookJSON.getGraphObject().getInnerJSONObject();
            dataJSONArray = jSONGraphAPI.getJSONArray("data");

            for (int i = 0; i < dataJSONArray.length(); i++) {
                JSONObject feedItem = dataJSONArray.getJSONObject(i);
                if (feedItem.has("created_time") && feedItem.has("message")) {
                    message = feedItem.getString("message");
                    createdTime = feedItem.getString("created_time");

                    if (feedItem.has("likes")) {
                        JSONObject likes = feedItem.getJSONObject("likes");
                        likeCount = likes.length();
                    }
                    // Adding value HashMap key => value
                    HashMap<String, String> map = new HashMap<String, String>();
                    map.put("message", message);
                    map.put("crated_time", createdTime);
                    map.put("likes", String.valueOf(likeCount));

                    dataList.add(map);
                }
                // Reset the values to put another data on the HashMap
                likeCount = 0;
                message = "";
                createdTime = "";
            }
        } catch (Exception e) {
            Log.e(TAG, e.getMessage());
        }
        feedsList = (ArrayList<HashMap<String, String>>) dataList.clone();
        Log.i("feedsList from jSONToArrayList method: ", feedsList.toString());
        return dataList;
    }
}

我想要获得的列表feedsList可以在我的适配器中使用它。但每次运行代码时，onCreateView方法中的列表都为空，但makePageRequest和jSONToArrayList方法中的列表已满。以下是我的logcat：

D/SelectionFragment(32558): onAttach method is called
D/SelectionFragment(32558): onCreate method is called
D/SelectionFragment(32558): onCreateView method is called

07-23 18:08:17.991: D/OpenGLRenderer(32558): Enabling debug mode 0
07-23 18:08:18.001: D/SelectionFragment(32558): makePageRequest method is called
07-23 18:08:19.221: D/SelectionFragment(32558): jSONToArrayList method is called
07-23 18:08:19.221: I/feedsList from jSONToArrayList method:(32558): [{crated_time=2014-07-23T17:53:22+0000, message=test 123, likes=2}, {crated_time=2014-07-14T10:05:09+0000, message=hello, likes=0}]

Answer 1

在makePageRequest方法中，您正在进行异步Web服务调用。调用jSONToArrayList(...)的回调仅在HTTP调用完成时调用。

但是你的代码在onCreateView方法中继续，而另一个线程正在发出HTTP请求。因此，当列表仍为空时，您的代码会立即将feedsList传递给SimpleAdapter构造函数。

您应该在重新分配feedsList字段后重新创建SimpleAdapter，或者不应该重新分配它（因为您已经传递了对SimpleAdapter的引用，在这种情况下您需要继续使用它参考。）。相反，您可以调用clear和addAll，并确保SimpleAdapter已正确通知列表内容的更改。

从内部阶级中获得一个arraylist的价值

1 个答案: