java - 在 AsyncTask 中覆盖执行前/后执行并调用 super.onPre/PostExecute

Question

在 AsyncTask 中覆盖 onPreExecute 时是否必须调用 super.onPreExecute？ AsyncTask.onPreExecute 和其他方法实际上做了什么？ onPostExecute 和 onCancelled 的相同问题

public class MyAsyncTask extends AsyncTask<Void, Void, Boolean> 
{

@Override
protected void onCancelled(Boolean result) {

    super.onCancelled(result);   //<-DO I HAVE TO?

            //My onCancelled code below


}

@Override
protected void onPostExecute(Boolean result) {

    super.onPostExecute(result);  //<-DO I HAVE TO?

            //My onPostExecute code below
}

@Override
protected void onPreExecute() {

    super.onPreExecute();  //<-DO I HAVE TO?

            //My onPreExecute code below

}

@Override
protected Boolean doInBackground(Void... params) {

    return null;
}

Answer 1

不，你不需要调用super。这是 source .

如您所见，默认实现不执行任何操作。

/**
* Runs on the UI thread before {@link #doInBackground}.
*
* @see #onPostExecute
* @see #doInBackground
*/
protected void onPreExecute() {
}

/**
* <p>Runs on the UI thread after {@link #doInBackground}. The
* specified result is the value returned by {@link #doInBackground}.</p>
*
* <p>This method won't be invoked if the task was cancelled.</p>
*
* @param result The result of the operation computed by {@link #doInBackground}.
*
* @see #onPreExecute
* @see #doInBackground
* @see #onCancelled(Object)
*/
@SuppressWarnings({"UnusedDeclaration"})
protected void onPostExecute(Result result) {
}