Android,空列表视图从其他片段返回

Question

Hy,我的片段中有列表视图.我用我的其他片段替换这个listview片段但是当我想要回到我的列表时,它是空的.我以为我可以恢复我的列表项目,但我不知道如何.我假设与Fragment生命周期一致,我的适配器将是可重用的,但看起来并非如此.这是我的代码:

public class ThreadListFragment extends Fragment implements FragmentConnectionStatus, ListFragment, OnClickListener, OnItemClickListener{
       private ListView ListView;
       private PilotController Activity;
       private Button ButtonStartNewThread;
       private boolean Paused;
       private ThreadInfoAdapter adapter;

@Override
   public View onCreateView(LayoutInflater inflater,
      ViewGroup container, Bundle savedInstanceState) {
      /**
   * Inflate the layout for this fragment
   */
        super.onCreateView(inflater, container, savedInstanceState);
        View view = inflater.inflate(R.layout.threads_list_fragment, container, false);
        System.out.println(this.Paused);
        if(this.Paused == false){
            this.ListView = (ListView) view.findViewById(R.id.listViewActiveThreads);
            ArrayList<Guid> strs = new ArrayList<Guid>();
            adapter = new ThreadInfoAdapter(view.getContext(), strs, this);
        }
        this.ListView.setAdapter(adapter);
        this.ListView.setItemsCanFocus(true);
        this.ListView.setOnItemClickListener(this);
        this.Activity = (PilotController) getActivity();
        this.ButtonStartNewThread = (Button) view.findViewById(R.id.buttonStartThread);
        this.ButtonStartNewThread.setOnClickListener(this);
        return view;
   }

@Override
public void onPause()
{
    super.onPause();
    this.Paused = true;
}

但当我回到我的旧名单时,它是空的.你能给我一些建议吗？

解

我找到了解决方案.ListView可能正在从'draw stack'中删除所以当调用OnDeleteView时,你的旧列表下次无法使用,尽管仍然设置了对该对象的引用.解决方案是重新创建ListView并设置旧适配器.由于本教程http://developer.android.com/guide/components/fragments.html的这个适配器将存活但视图被重新创建(所以旧的listview不再存在(它存在但它不可绘制).我不得不改变这一行:

    if(this.Paused == false){
        this.ListView = (ListView) view.findViewById(R.id.listViewActiveThreads);
        ArrayList<Guid> strs = new ArrayList<Guid>();
        adapter = new ThreadInfoAdapter(view.getContext(), strs, this);
    }

至:

    this.ListView = (ListView) view.findViewById(R.id.listViewActiveThreads);
    if(this.Paused == false){
        ArrayList<Guid> strs = new ArrayList<Guid>();
        adapter = new ThreadInfoAdapter(view.getContext(), strs, this);
    }

Answer 1

在“onActivityCreated”中，您可以检查您的dataList（在您的情况下为“strs”）是否为空。如果不是，则使用它，否则创建一个新的。在代码中，它看起来像这样：

public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

    if (strs == null)
        strs = new ArrayList<Guid>();

    mListView = (ListView)getActivity().findViewById(R.id.listViewActiveThreads);

    mPersonAdapter = new ArrayAdapterPerson(getActivity(),mPersonList,this);
    mListView.setAdapter(mPersonAdapter);

}