Question

我的活动有ActionBar和tabs。每个选项卡代表一个片段，所有片段都在唯一的活动中运行。

我在第一个fragment内有一个Spinner和一个ListView。在Spinner中选择项目时，ListView的数据将被修改并正确显示。

当我选择第二个选项卡，在那里执行某些操作并导航回第一个选项卡时，会出现问题。在Spinner上选择项目后，ListView没有更新。

RouteFragment：

public class RouteFragment extends FragmentBase {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
            Bundle savedInstanceState) {

        View fragView = inflater.inflate(R.layout.route, container, false);

        Spinner spinner = (Spinner) fragView.findViewById(R.id.route_list);
        ArrayAdapter<Route> routeListAdapter = new ArrayAdapter<Route>(this.getActivity(), 
                android.R.layout.simple_spinner_item, 
                this.adapter.getRouteList());
        spinner.setAdapter(routeListAdapter);


        long routeId = ((Route) spinner.getSelectedItem()).Id;

        ListView lv = (ListView) fragView.findViewById(R.id.client_list);
        final ClientAdapter clientListAdapter = new ClientAdapter(this.getActivity(), 
                R.layout.route_listview,
                this.adapter.getClientList(routeId));
        lv.setAdapter(clientListAdapter);


        routeListAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

        spinner.setOnItemSelectedListener(new RouteSpinnerItemSelectedListener(lv));

        return fragView;
    }
}

的 RouteSpinnerItemSelectedListener：

public class RouteSpinnerItemSelectedListener implements OnItemSelectedListener {

    private ListView lv;

    public RouteSpinnerItemSelectedListener(ListView fragView) {
        this.lv = fragView;
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view,
            int position, long id) {

        Route route = (Route) parent.getItemAtPosition(position);

        android.util.Log.v("Salesman", "selected route id: " + route.Id);
        android.util.Log.v("Salesman", "selected route name: " + route.Name);


        ClientAdapter clientAdapter = (ClientAdapter) lv.getAdapter();

        Log.v("Salesman", "before clear: " + clientAdapter.getCount() + "");

        clientAdapter.clear();

        Log.v("Salesman", "after clear: " + clientAdapter.getCount() + "");

        List<Client> clientList = DataAdapter.getInstance(Main.getContext())
        .getClientList(route.Id);

        Log.v("Salesman", "raw from DB" + clientList.size() + "");

        clientAdapter.addAll(clientList);

        Log.v("Salesman", "after addAll()"  +  clientAdapter.getCount() + "");
        clientAdapter.notifyDataSetChanged();
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {
        // TODO Auto-generated method stub

    }
}

TabListener：

public class TabListener implements ActionBar.TabListener {
    private FragmentBase mFragment;

    public TabListener(FragmentBase fragment) {
        this.mFragment = fragment;
    }

    public void onTabSelected(Tab tab, FragmentTransaction ft) {
        ft.add(R.id.fragment_content, mFragment, mFragment.getName());
    }

    public void onTabUnselected(Tab tab, FragmentTransaction ft) {
        ft.remove(mFragment);
    }

    public void onTabReselected(Tab tab, FragmentTransaction ft) {
        android.util.Log.v("Salesman", "reselected");
    }

}

我从数据库中获取的列表clientList不是空的，我已经检查过了，正如您在代码中看到的那样。但是，ListView为空且没有反应并保持为空。

我想重点是我失去了我的ListView，但我只是不明白在哪里。

还有一件事：只有当我从一个标签移动到另一个标签时才会出现此问题。当我移动到我的应用程序内的另一个活动然后向后移动时，我仍然可以看到列表视图（它不是空的）并且可以更新它。

你能指点吗？

Answer 1

我认为这会在状态发生变化后处理片段事务时发生，

getFragmentManager().beginTransaction().show(fragment).commitAllowingStateLoss();

或

getFragmentManager().beginTransaction().add(R.id.layout,fragment).commitAllowingStateLoss();

或

getFragmentManager().beginTransaction().replace(R.id.layout,fragment).commitAllowingStateLoss();

然后，

getFragmentManager().executePendingTransactions();

已编辑... RouteSpinnerItemSelectedListener

public class RouteSpinnerItemSelectedListener implements OnItemSelectedListener {

private ListView lv;

public RouteSpinnerItemSelectedListener(ListView fragView) {
    this.lv = fragView;
}

@Override
public void onItemSelected(AdapterView<?> parent, View view,
        int position, long id) {
 if(lv!=null)
 {
    Route route = (Route) parent.getItemAtPosition(position);

    android.util.Log.v("Salesman", "selected route id: " + route.Id);
    android.util.Log.v("Salesman", "selected route name: " + route.Name);


    ClientAdapter clientAdapter = (ClientAdapter) lv.getAdapter();
   if(clientAdapter !=null)
   {
    Log.v("Salesman", "before clear: " + clientAdapter.getCount() + "");

    clientAdapter.clear();

    Log.v("Salesman", "after clear: " + clientAdapter.getCount() + "");

    List<Client> clientList = DataAdapter.getInstance(Main.getContext())
    .getClientList(route.Id);

    Log.v("Salesman", "raw from DB" + clientList.size() + "");

    clientAdapter.addAll(clientList);

    Log.v("Salesman", "after addAll()"  +  clientAdapter.getCount() + "");
    clientAdapter.notifyDataSetChanged();
   }
   else
   {
      ClientAdapter clientAdapter = = new ClientAdapter(this.getActivity(), 
            R.layout.route_listview,
            this.adapter.getClientList(routeId));
      List<Client> clientList = DataAdapter.getInstance(Main.getContext())
      .getClientList(route.Id);
      clientAdapter.clear();
      clientAdapter.addAll(clientList);
      lv.setAdapter(clientListAdapter);
   }
 }
 else
 {
      lv=(ListView)getActivity.findViewById(R.id.route_list);
      ClientAdapter clientAdapter = = new ClientAdapter(this.getActivity(), 
            R.layout.route_listview,
            this.adapter.getClientList(routeId));
      List<Client> clientList = DataAdapter.getInstance(Main.getContext())
      .getClientList(route.Id);
      clientAdapter.clear();
      clientAdapter.addAll(clientList);
      lv.setAdapter(clientListAdapter);
 }
}

@Override
public void onNothingSelected(AdapterView<?> parent) {
    // TODO Auto-generated method stub

 }
}

更改为另一个选项卡时，片段中的ListView会丢失

1 个答案: