Question

我正在尝试在我的Android应用程序上使用ListActivity，但它没有按照应有的方式工作这是我的活动：

public class MainActivity extends ListActivity {

    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_terminals_list); //The special layout

        TerminalsArrayAdapter adapter = new TerminalsArrayAdapter(this); // A custom adapter
        setListAdapter(adapter);
        RequestTask task = new RequestTask(adapter); // An Async task
        task.execute("/terminals/all");
    }
}

这是我的布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <ListView 
        android:id="@android:id/list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >
    </ListView>

    <TextView
        android:id="@android:id/empty"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Loading..." />
</LinearLayout>

这是我的自定义适配器：

public class TerminalsArrayAdapter extends ArrayAdapter<String[]> {

    private Activity mContext;
    private ArrayList<String[]> mObjects = new ArrayList<String[]>();

    public TerminalsArrayAdapter(Activity context) {
        super(context, R.layout.terminals_listview_item);
        this.mContext = context;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View elementView;

        if(convertView==null){
            LayoutInflater inflater = mContext.getLayoutInflater();
            elementView = inflater.inflate(R.layout.terminals_listview_item, parent);
            ...
            // Some things with my view

        } else {
            elementView = convertView;
        }

        ...
        // Some things with my view
        return elementView;
    }

    public void updateTerminals(ArrayList<String[]> newObject){
        mObjects.clear();
        mObjects.addAll(newObject);
        notifyDataSetChanged();
        Log.d("TerminalsArrayAdapter", "Dataset Changed !");
    }
}

这是我的异步任务：

public class RequestTask extends AsyncTask<String, Void, ArrayList<String[]>>{

    private final TerminalsArrayAdapter mAdapter;

    public RequestTask(TerminalsArrayAdapter adapter) {
        mAdapter = adapter;
    }

    @Override
    protected ArrayList<String[]> doInBackground(String... params) {

        ...
        // retrieve some data from my server
        return response;
    }

    @Override
    protected void onPostExecute(ArrayList<String[]> response) {
        Log.d("response_server","GOT IT !");
        mAdapter.updateTerminals(response);
    }
}

据我所知，只有在适配器不为空时才会显示ListView。如果它是空的，它将是将显示的TextView。

这是我的应用程序应该工作的方式：

该应用会创建一个空适配器。这将显示“正在加载...”TextView
该应用程序会创建一个新的Async任务，该任务将从我的服务器中检索一些所需的数据
当Async任务完成时，它将调用.updateTerminals（）方法
此方法将更新自定义适配器的条目并调用notifyDataSetChanged（）
应用程序现在应该显示带有新检索数据的ListView

步骤1到4工作正常。问题出现在第5步：即使数据已更新，我的应用程序也不刷新屏幕以显示ListView并保持在“正在加载...”TextView。

我试图找出我的代码有什么问题，但我无法做到。我很想听听你的建议/解决方案！谢谢！

PS：告诉我你是否需要更好地理解我的问题。

Answer 1

ListView身高应为match_parent。

尝试使用setVisibility(View.GONE)和setVisibility(View.VISIBLE)来玩：

显示TextView＆amp;隐藏ListView
显示ListView＆amp;隐藏TextView

Answer 2

public class MainActivity extends ListActivity {

    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_terminals_list); //The special layout
        // create your list with specific method to be able call her many time
        // prefer to create then refresh with new data
         CreateList(Passanydata);
         RequestTask task = new RequestTask(adapter); // An Async task
            task.execute("/terminals/all");

    }
}

public void CreateList(ArrayList<String[]> response){
 TerminalsArrayAdapter adapter = new TerminalsArrayAdapter(this,response); // A custom adapter
            setListAdapter(adapter);

}



 @Override
    protected void onPostExecute(ArrayList<String[]> response) {
        Log.d("response_server","GOT IT !");
      // after you got your new data , pass it to your list 
       CreateList(response);
    }




public class TerminalsArrayAdapter extends ArrayAdapter<String[]> {

    private Activity mContext;
    private ArrayList<String[]> mObjects = new ArrayList<String[]>();

    public TerminalsArrayAdapter(Activity context,ArrayList<String[]> objects) {
        super(context, R.layout.terminals_listview_item);
        this.mContext = context;
        // when you have your data it will be able to use it here 
        this.mObjects  = objects;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View elementView;

        if(convertView==null){
            LayoutInflater inflater = mContext.getLayoutInflater();
            elementView = inflater.inflate(R.layout.terminals_listview_item, parent);
            ...
            // Some things with my view

        } else {
            elementView = convertView;
        }

        ...
        // Some things with my view
        return elementView;
    }


}

为什么我的ListActivity卡在/ empty元素上？

2 个答案: