android - 异步任务奇怪的行为

Question

我在使用 asynctask 时遇到了一些奇怪的警告。我正在学习 GCM，所以我尝试使用 asynctask。这是警告:

Type safety: The method execute(Object...) belongs to the raw type AsyncTask. References to generic type AsyncTask<Params,Progress,Result> should be parameterized

我想了解这个警告的含义。它是关于线程的。为什么它不安全？这是什么原料？

这是我的代码:

private void registerInBackground() {
    // TODO Auto-generated method stub



    new AsyncTask() {
        @Override
        protected Object doInBackground(Object... arg0) {
            // TODO Auto-generated method stub
            String msg = "";
            try {
                if (gcm == null) {
                    gcm = GoogleCloudMessaging.getInstance(getApplicationContext());
                }
                regid = gcm.register(SENDER_ID);
                msg = "Device registered, registration ID=" + regid;

                // You should send the registration ID to your server over HTTP,
                // so it can use GCM/HTTP or CCS to send messages to your app.
                // The request to your server should be authenticated if your app
                // is using accounts.
                sendRegistrationIdToBackend();

                // For this demo: we don't need to send it because the device
                // will send upstream messages to a server that echo back the
                // message using the 'from' address in the message.

                // Persist the regID - no need to register again.
                storeRegistrationId(getApplicationContext(), regid);
            } catch (IOException ex) {
                msg = "Error :" + ex.getMessage();
                // If there is an error, don't just keep trying to register.
                // Require the user to click a button again, or perform
                // exponential back-off.
            }
            return msg;
        }   @Override
        protected void onPostExecute(Object result) {
            // TODO Auto-generated method stub
            super.onPostExecute(result);
            Toast.makeText(getApplicationContext(), ""+result.toString(), Toast.LENGTH_LONG).show();
        }
    }.execute(null, null, null);



}

谢谢

Answer 1

AsyncTask 是一个 generic Class可以参数化。该警告意味着您应该明确命名参数。

AsyncTask 定义为 AsyncTask<Params,Progress,Result> , 它需要 3 个参数 Params , Progress和 Result可以是任何类型/类。

在上面的代码中，您在 doInBackground() 中返回了一个字符串. doInBackground() 的返回值是 AsyncTask 的第三个参数(Result)。

要使警告消失，请实现您的 AsyncTask像这样:

new AsyncTask<Void, Void, String>() {
        @Override
        protected String doInBackground(Void... voids) {
            String message = "";

            //do something

            return message;
        }

        @Override
        protected void onPostExecute(String result) {

        }
    }.execute();