使用AsyncTask填充ListView（doInBackground（）返回光标）

Question

我想使用AsyncTask填充我的ListView。在评论

private class DownloadDataTask extends AsyncTask<String, Void, Cursor> { 
    private final ProgressDialog dialog = new ProgressDialog(ctx); 


    @Override 
    protected void onPreExecute() { 
     this.dialog.setMessage(ctx.getString(R.string.AcquiringData)); 
     this.dialog.show(); 
    } 


    @Override 
    protected Cursor doInBackground(final String... args) {   

     DbAdapter dbAdapter = new DbAdapter(ctx); 
     dbAdapter.open(); 
     // normally when I call this method from main class it reurns cursor full of values 
     Cursor cursor = dbAdapter.fetchAllItemsInExpenses(); 

     return cursor; 
    } 


    protected void onPostExecute(final Cursor cursor) { 
     if (this.dialog.isShowing()) { 
      this.dialog.dismiss(); 
      //cursor is empty 

    } 

ctx包含的问题是，设置在主类的OnCreate（）

按照要求粘贴fetchAllItemsInExpenses（）方法上下文：

public Cursor fetchAllItemsInExpenses() { 
    String query = "SELECT ... " //(some terribly boring and long query string, but trust me, it works perfectly fine) 
    return SQLDb.rawQuery(query, null); 
} 

Answer 1

在AsyncTask试试这个...

private class DownloadDataTask extends AsyncTask<String, Void, Cursor> { 
    private final ProgressDialog dialog = new ProgressDialog(ctx); 
    Context ctx = null; //Add this and the constructor below 

    public DownloadDataTask(Context context) { 
     ctx = context; 
    } 

    ... 

} 

然后在你身边[R Activity创建并执行AsyncTask如下...

DownloadDataTask ddt = new DownloadDataTask(this); 
ddt.execute(theArgs);