无法停止/重启 AsyncTask

问题描述

请帮忙.我可以重新启动 AsyncTask.应用程序每次都崩溃，当第二次调用 updatePoi() 时.

Please help. I can restart the AsyncTask. App crashes every time, when second call to updatePoi().

这是我的代码:

1. 我正在检查任务状态并设置取消(true).

1. I'm checking status of task and set cancel(true).

public void updatePoi() {
    //new RefreshMapTask().execute();
    if (refreshMapTask.getStatus() == AsyncTask.Status.RUNNING ||
        refreshMapTask.getStatus() == AsyncTask.Status.PENDING) {
            refreshMapTask.cancel(true);
        }
        refreshMapTask.execute();
    }
}

这是我的 AsyncTask.在 doInBackground 我写了一个休息.

Here is my AsyncTask. in doInBackground I wrote a break.

private class RefreshMapTask extends AsyncTask<Void, Void, Void> {
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        getMapView().getOverlays().clear();
        myPoiOverlay.clear();
        exitOverlay.clear();
    }


    @Override
    protected Void doInBackground(Void... voids) {
        Application app = (Application)getApplication();
        Log.d(TAG, "exits count = " + app.getExits().size());

        GeoPoint pointToNavigate = null;

        for (Exit exit : app.getExits()) {

            for (Poi poi : exit.getPoi()) {
                if (isCancelled()){
                    break;
                }
                //some code here
            }
        }

        //small code here
        return null;
    }

    @Override
    protected void onPostExecute(Void aVoid) {
        getMapView().invalidate();
    }
}

将评论中的解决方案添加到问题中

added solution from comments into the question

 public void updatePoi() {
//new RefreshMapTask().execute();
if (refreshMapTask.getStatus() == AsyncTask.Status.RUNNING ||
    refreshMapTask.getStatus() == AsyncTask.Status.PENDING){
    refreshMapTask.cancel(true);
    refreshMapTask = new RefreshMapTask();
} else {
    refreshMapTask = new RefreshMapTask();
}
refreshMapTask.execute();
}

推荐答案

一个 AsyncTask 实例只能被调用一次.要进行第二次调用，您需要创建一个新实例.

An AsyncTask instance can only be called once. To make a second call, you need to create a new instance.

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