[英]how to return string from AsyncTask to another activity
我已经创建了一个类并使用AsyncTask进行了扩展,现在我想向我返回一个字符串以将另一个类抛出该活动。 它从mysql mDatabase获取jsonstring
enter code here
public class GetJson extends AsyncTask<Void,Void,String> {
String JSON_STRING;
String json_url;
public String pasString;
Activity ab;
@Override
protected void onPreExecute() {
json_url="https://XXXXXXX.000webhostapp.com/Json_getData_Survey.php";
}
public GetJson(Activity b) {
ab=b;
}
@Override
protected String doInBackground(Void... params) {
try {
URL url =new URL(json_url);
HttpURLConnection httpURLConnection =(HttpURLConnection) url.openConnection();
InputStream inputStream =httpURLConnection.getInputStream();
BufferedReader bufferedReader=new BufferedReader(new InputStreamReader(inputStream));
StringBuilder stringBuilder=new StringBuilder();
while ((JSON_STRING=bufferedReader.readLine())!=null)
{
stringBuilder.append(JSON_STRING+"\n");
}
bufferedReader.close();
inputStream.close();
httpURLConnection.disconnect();
String strings =stringBuilder.toString().trim();
return strings;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onProgressUpdate(Void... values) {
super.onProgressUpdate(values);
}
@Override
protected void onPostExecute(String result) {
pasString=result;
// Toast.makeText(ab,pasString,Toast.LENGTH_LONG).show();
// json_string1=result;
}
}
我只需要将string1返回到另一个Activity,我在GetJson类中创建了另一个方法来返回此字符串,但是当我显示此字符串时,它什么也没有显示。 请帮忙
它非常简单,使接口类如下
public interface ResponseListener() {
void onResponseReceive(String data);
}
并像这样在您的GetJson类中添加此类的实例
public class GetJson extends AsyncTask<Void,Void,String> {
String JSON_STRING;
String json_url;
public String pasString;
Activity ab;
// this is new code
ResponseListener listener;
public void setOnResponseListener(ResponseListener listener) {
this.listener = listener;
}
@Override
protected void onPreExecute() {
json_url="https://XXXXXXX.000webhostapp.com/Json_getData_Survey.php";
}
// now add this code in onPost function
@Override
protected void onPostExecute(String result) {
pasString=result;
listener.onResponseReceive(pasString);
// Toast.makeText(ab,pasString,Toast.LENGTH_LONG).show();
// json_string1=result;
}
现在,当您从活动中调用GetJson时,只需执行以下操作即可;
GetJson json = new GetJson(Activity.this);
json.setOnResponseListener(new ResponseListener() {
@Override
public void onResponseReceived(String data) {
// here you will get your response
}
});
希望你能理解。 :)
尝试使用活动结果。 您可以为一个活动设置返回值,并在该活动终止时获取它。
https://developer.android.com/training/basics/intents/result.html
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