无法解析符号“执行”...调用 AsyncTask

Question

我正在尝试在 URL 上发出 GET 请求，我创建了一个扩展 AsyncTask<Void, Void, Void> 的类，我尝试调用 new MyClass.execute() ...我以前做过这个并且它有效，今天它不工作.我做错了什么？

这是我的代码：

public class SignUpActivity extends AppCompatActivity {

String TAG = SignUpActivity.class.getSimpleName();
String URL;

ArrayList<String> countries = new ArrayList<>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_sign_up);

    new MyClass.execute();
}

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

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        //TODO
    }

    @Override
    protected Void doInBackground(Void... params) {
        HttpHandler sh = new HttpHandler();

        // Making a request to url and getting response
        String jsonStr = sh.makeServiceCall(URL, "GET");
        //Handling response in jsonStr code 
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
        //TODO
    }

}

Answer 1

这是一个语法错误。应该是

new MyClass().execute();

不像 new MyClass.execute();

Answer 2

使用这个获取数据使用返回返回值：

   public class SignUpActivity extends AppCompatActivity {

    String TAG = SignUpActivity.class.getSimpleName();
    String URL;

    ArrayList<String> countries = new ArrayList<>();

    String jsonStr="";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_sign_up);

        String response = new MyClass.execute();


    }

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

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            //TODP
        }

        @Override
        protected String doInBackground(Void... params) {
            HttpHandler sh = new HttpHandler();

            // Making a request to url and getting response
            String jsonStr = sh.makeServiceCall(URL, "GET");
            //Handling response in jsonStr code 
            return jsonStr;
        }

        @Override
        protected void onPostExecute(String result) {
            super.onPostExecute(result);
            //TODO
            jsonStr = result;
        }

    }
}

Answer 3

public class JsonHandler {

    static String response = null;
    public final static int GET = 1;
    public final static int POST = 2;

    public JsonHandler() {

    }

    public String makeServiceCall(String url,int method) {
        return this.makeServiceCall(url, method, null);
    }

    public String makeServiceCall(String url, int method,
            List<NameValuePair> params) {

        try {
            // http client
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpEntity httpEntity = null;
            HttpResponse httpResponse = null;

            // Checking http request method type
            if (method == POST) {
                HttpPost httpPost = new HttpPost(url);

                if (params != null) {
                    httpPost.setEntity(new UrlEncodedFormEntity(params));
                }

                httpResponse = httpClient.execute(httpPost);
            } else if (method == GET) {
                if (params != null) {
                    String paramString = URLEncodedUtils.format(params, "utf-8");
                    url += "?" + paramString;
                }

                HttpGet httpGet = new HttpGet(url);
                httpResponse = httpClient.execute(httpGet);
            }

            httpEntity = httpResponse.getEntity();
            response = EntityUtils.toString(httpEntity);
        } catch (Exception e) {
        }

        return response;
    }

}

将上面的类添加到你的主包中并作为doInBackground进行

@Override
        protected  Void doInBackground(String... params) {
            // TODO Auto-generated method stub
            JsonHandler json = new JsonHandler();
            String jsonStr = json.makeServiceCall(params[0], JsonHandler.GET);

          // parse your json data here
        }