首先,我必须说,我读过这个:
How to get the return value from onpostexecute method in android?
那:
How do I return a boolean from AsyncTask?
没有任何帮助,也许我不明白他们在说什么。 这是我的问题: 我只需要取回我的OnPostExecute方法中的String值。 不是来自doInBackground,我需要从我的OnPostExecute。
我的代码:
public void max(String build,String cls)
{
BackgroundTask3 myTask = new BackgroundTask3();
myTask.execute(build,cls);
Toast.makeText(getApplicationContext(),"fcur is" + Fcur,Toast.LENGTH_LONG).show();
}
和
public class BackgroundTask3 extends AsyncTask<String,Void,String>
{
String capacity_url;
@Override
protected void onProgressUpdate(Void... values) {
super.onProgressUpdate(values);
}
@Override
protected void onPostExecute(String result) {
String finalValue;
json_capacity = result;
finalValue=parseMax();
Toast.makeText(getApplicationContext(),"finalValue is" + finalValue,Toast.LENGTH_LONG).show();
super.onPostExecute(result);
}
@Override
protected void onPreExecute() {
capacity_url = "http://www.skedge.co.il/ANCurrentCapacity.php";
}
@Override
protected String doInBackground(String... params) {
String cls,build;
build= params[0];
cls = params[1];
try {
URL url = new URL (capacity_url);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoOutput(true);
OutputStream outputStream = httpURLConnection.getOutputStream();
BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream,"UTF-8"));
String data_string = URLEncoder.encode("Fclass","UTF-8")+"="+URLEncoder.encode(cls,"UTF-8")+"&"+
URLEncoder.encode("building","UTF-8")+"="+URLEncoder.encode(build,"UTF-8")+"&"+
URLEncoder.encode("hour","UTF-8")+"="+URLEncoder.encode(hour,"UTF-8");
bufferedWriter.write(data_string);
bufferedWriter.flush();
bufferedWriter.close();
//here is the new
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream,"UTF-8"));
StringBuilder stringBuilder = new StringBuilder();
while ((JSON_STRING = bufferedReader.readLine())!= null)
{
stringBuilder.append(JSON_STRING+"\n");
}
outputStream.close();
inputStream.close();
httpURLConnection.disconnect();
return stringBuilder.toString().trim();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
}
我想做的就是: 将OnPostExecute中finalValue String中的值赋给最大函数内部的Fcur(public String)。
看起来很简单,但由于某种原因,我无法完成它。
答案 0 :(得分:2)
从后台线程获取回调的最佳方法是使用interfaces
作为AsyncTask
的回调,例如:
创建一个可以在onPostExecute()
public interface ResponseCallback {
void onRespond();
}
并在调用asynckTask之前定义它:
ResponseCallback callback = new ResponseCallback() {
@Override
public void onRespond() {
//code to be done after calling it from onPostExecute
}
};
并将callback
传递给constructor
的{{1}}并在asynckTask
当然,您可以将onPostExecute
的签名修改为您想要的内容。