Question

我需要从AsyncTask访问一个Object。这是AsyncTask的代码：

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

    // Downloading data in non-ui thread
    @Override
    protected String doInBackground(String... url) {

        // For storing data from web service
        String data = "";

        try{
            // Fetching the data from web service
            data = downloadUrl(url[0]);
        }catch(Exception e){
            Log.d("Background Task",e.toString());
        }
        return data;
    }

    // Executes in UI thread, after the execution of
    // doInBackground()
    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);

        ParserTask parserTask = new ParserTask();

        // Invokes the thread for parsing the JSON data
        parserTask.execute(result);
    }
}

我想访问data。我不知道我该怎么做。

Answer 1

另一个替代方法是使用private static modifier声明data变量并创建一个public static get方法。从第二个活动可以直接访问该公共静态方法。

private class FirstAcitivity extends Activity
{
    private static String data = "";

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

        // Downloading data in non-ui thread
        @Override
        protected String doInBackground(String... url) {

            // For storing data from web service
            //String data = "";                                                    // Comment this line 

            try{
                // Fetching the data from web service
                data = downloadUrl(url[0]);
            }catch(Exception e){
                Log.d("Background Task",e.toString());
            }
            return data;
        }

        // Executes in UI thread, after the execution of
        // doInBackground()
        @Override
        protected void onPostExecute(String result) {
            super.onPostExecute(result);

            ParserTask parserTask = new ParserTask();

            // Invokes the thread for parsing the JSON data
            parserTask.execute(result);
        }
    }

    public static String getData()
    {
        return data;
    }
}

现在访问第二个活动

public class SecondActivity extends Activity 
{ 
    String data = FirstActivity.getData();

}

Answer 2

您也可以通过将变量声明如下来访问它：

 public static String data="";

然后您可以在其他活动中访问它：

 ClassName.data

其中ClassName将是您定义变量的类的名称。

从AsyncTask外部访问对象

2 个答案: