Android异步任务不起作用

Question

I am calling this from a function by creating an object.The progress box appears and then disappears but the toast is not displayed.(I have removed the code that follows the toast but even that code which queries the web page is not executed in the doinBackground)

private class MyTask extends AsyncTask<Void, Void, Void> {

    MyTask(String p) {
        enter=p;
    }

    protected void onPreExecute() {
        progressDialog = ProgressDialog.show(CheckitoutActivity.this,"", "Loading. Please wait...", true);
    }

    protected Void doInBackground(Void... params) {
        try {
            Toast.makeText(getApplicationContext(), "GHJGFHGJL",1000).show();
         }
    }


     @Override
     protected void onPostExecute(Void result) {
         progressDialog.dismiss();
     }

}

The doInBackground does not apppear to be called. Even the toast is not displayed.Why is that.

Answer 1

doInBackground method is non UI thread so it can't dispaly a toast

So use runOnUIthread(this) or onProgressUpdate and are sure .execute() with object, like objMytask.execute();

Answer 2

Toast (You can't touch UI Thread from doInBack() that's why) is not works in doInBackground() so just put Log

protected Void doInBackground(Void... params) {
 try 
 {
  Log.e("AsyncTask","Inside the doInBackground()");
 }
}

Now check your logcat ... If ProgressDailog is showing then your AsyncTask is works well.

Answer 3

you can not display the UI like toast and dialog alert in doInBackground method. instead you can show these UI in postExecute method of asynkTask