Question

我正在使用fragment和viewpager撰写一个简单的应用来显示来自webservice的数据。问题是viewpager第一次创建3 fragments，但数据仅在最后fragment上查看。

这是我的活动：

public class LineDetailTabs extends FragmentActivity {
//declare some variables here

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_line_detail_tabs);

    FragmentManager fragmentManager = getSupportFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager
            .beginTransaction();
    PlaceholderFragment hf = new PlaceholderFragment();
    fragmentTransaction.replace(R.id.container, hf);
    fragmentTransaction.commit();

    mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

    // Set up the ViewPager with the sections adapter.
    mViewPager = (ViewPager) findViewById(R.id.container);
    mViewPager.setAdapter(mSectionsPagerAdapter);
    mViewPager.setCurrentItem(index);
    }

这是我的适配器， list_nodep 是一个String数组，包含许多deparments的id。计数是部门数量，也会创建标签数量。

public class SectionsPagerAdapter extends FragmentStatePagerAdapter {
    public SectionsPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        noDep = list_nodep[position];

        PlaceholderFragment fragment = new PlaceholderFragment();
        Bundle args = new Bundle();
        //put some agurments
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public int getCount() {
        return count;
    }
}

我的片段在这里，所有片段都有相同的布局xml文件。

public static class PlaceholderFragment extends Fragment {
    public static View rootView;

    public static TextView tvHeader;
    public static TextView tvPO;
    public static TextView tvLot;
    // many textviews

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
      activity = (LineDetailTabs) getActivity();
      loadData(noDep, date, username, dbIP, dbName, dbUsername, dbPassword);

      rootView = inflater.inflate(R.layout.fragment_line_detail_tabs, container, false);
      tvHeader = (TextView) rootView.findViewById(R.id.txtHeader);
      tvPO = (TextView) rootView.findViewById(R.id.txtPO);
      tvLot = (TextView) rootView.findViewById(R.id.txtLOT);
      // many textviews remaining...

      return rootView;
    }

public static void loadData(String aNoDep, String aDate, String aUsername, String aDbIP, String aDbName, String aDbUser, String aDbPass) {
            RequestParams params = new RequestParams();
            //put params

            invokeWS(params);
     }

public static void invokeWS(final RequestParams params) {

                 AsyncHttpClient client = new AsyncHttpClient();
                 client.get("http://...", params, new AsyncHttpResponseHandler() {
                        @Override
                        public void onSuccess(int statusCode, Header[] headers, String response) {
                        try {
                            // JSON Object
                            JSONObject obj = new JSONObject(response);
                            // When the JSON response has status boolean value assigned with true

                            JSONArray jArr = obj.getJSONArray("list");

                            // Display info detail on screen
                            obj = jArr.getJSONObject(0);

                            tvHeader.setText = obj.getString("NAME_DEP");
                            tvPO.setText = obj.getString("NO_PO");
                            tvLot.setText = obj.getString("NO_LOT");
                            //set text for all textviews
                    }
                    // When the response returned by REST has Http response code other than '200'
                    @Override
                    public void onFailure(int statusCode, Throwable error,
                                          String content) {
                        // When Http response code is '404'
                        if (statusCode == 404) {
                            Toast.makeText(activity.getApplicationContext(), Constants.ERR_CODE_404, Toast.LENGTH_SHORT).show();
                        }
                        // When Http response code is '500'
                        else if (statusCode == 500) {
                            Toast.makeText(activity.getApplicationContext(), Constants.ERR_CODE_500, Toast.LENGTH_SHORT).show();
                        }
                        // When Http response code other than 404, 500
                        else {
                            Toast.makeText(activity.getApplicationContext(), Constants.ERR_CODE_, Toast.LENGTH_SHORT).show();
                        }
                    }
                });
         }
    }

调试我的应用时，我看到fragment onCreateView连续运行3次，之后光标跳转到onSuccess，所以只显示最后fragment个数据。我想我把loadData()方法或setText放在了错误的地方。请帮忙。

Answer 1

好的，最后我修好了。这是我的错误，我没有将params从活动传递到碎片。把para放在这里

span

然后在onCreateView（）中获取这些参数，并调用loadData（）方法。

Map<Point, BufferedImage> loadedImages = new ConcurrentHashMap<>();
Deque<Point> lastUsed = new ConcurrentLinkedDeque<>();

int getRGB(double tileX, double tileY) {
    Point point = new Point((int) tileX, (int) tileY);
    if (!loadedImages.containsKey(point)) {
        loadedImages.put(point, ImageIO.read(new File("R:\\tiles\\22\\" + point.y + "_" + point.x + ".jpg")));
        lastUsed.addLast(point);
    }
    BufferedImage img = loadedImages.get(point);
    if (loadedImages.size() > 1000) {
        loadedImages.remove(lastUsed.pollFirst());
    }
    //do stuff with img
}

Android viewpager只显示最后一个片段视图的数据

1 个答案: