AsyncTask执行，但仅在某些情况下执行 [英] AsyncTask executes but only sometimes

问题描述

所以我用这段代码来调用我的AsyncTask

So i use this code to call my AsyncTask

Log.d("before","make_connection");
new Make_Connection().execute();
Log.d("after","make_connection");

我的课

private class Make_Connection extends AsyncTask<Void,Void,String>{

    final int port = 4445;

    @Override
    protected void onPreExecute() {
        Toast.makeText(KeyboardActivity.this,"This runs",Toast.LENGTH_LONG).show();
    }

    @Override
    protected String doInBackground(Void... params) {
        Log.d("Connection","Started");
        Log.e("Connec","this runs");
        try {
            socket = new Socket(IP,port);
            //dout = new DataOutputStream(socket.getOutputStream());
            //dout.writeUTF("Connection Formed");
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

    protected void onPostExecute(String result) {
        Toast.makeText(KeyboardActivity.this,"Connection Made",Toast.LENGTH_SHORT).show();
    }


}

现在我可以在android监视器中看到这两个始终执行

Now i can see in the android monitor that these two are always execute

Log.d("before","make_connection");
Log.d("after","make_connection");

但是有一半时间我看不到产生的输出

But half of the time i cannot see the output produced by

Log.d("Connection","Started");
Log.e("Connec","this runs");

即使onPreExecute()每次都能正常运行. 我已经对运行7.1和7.0的两种不同的移动设备进行了测试

Even though onPreExecute() runs properly everytime. I have tested on two diffent mobilies running 7.1 and 7.0

有人可以告诉我为什么会发生这种情况吗

Can someone please tell me why this is happening

推荐答案

尝试:

new Make_Connection().executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);

而不只是

new Make_Connection().execute();

这是必需的，因为在默认情况下，它们在Android SDK 13或更高版本中按顺序运行.因此，如果要同时运行多个AsyncTask，请使用executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR) 有关更多详细信息，请参见该文档

This is needed, because in Android SDK 13 or higher they run serially by default. So if you want to run more than one AsyncTask simultaneously, use executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR) For more details, see explanation under order of execution from This docs

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