How can I return value from function onResponse of Volley?
public class getString {
String tag_string_req = "string_raq";
String url = "http://10.0.2.2/eat/locations/index.json";
String result="";
public String get_String() {
StringRequest strReq = new StringRequest(Request.Method.GET, url, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
result=response;
System.out.println(response);
;
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError volleyError) {
System.out.println(volleyError.getMessage());
}
});
AppController.getInstance().addToRequestQueue(strReq, tag_string_req);
return result;
}}
I would to build an object of getString and call get_String in other fields. But it seems that it is hard to get the result out from the onResponse. I know it cannot work in this current way. Could anyone help me to settle this problem?
You want to use callback interfaces like so:
public void getString(final VolleyCallback callback) {
StringRequest strReq = new StringRequest(Request.Method.GET, url, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
... // (optionally) some manipulation of the response
callback.onSuccess(response);
}
}...
}}
Where the callback is defined as
public interface VolleyCallback{
void onSuccess(String result);
}
Example code inside activity:
public void onResume(){
super.onResume();
getString(new VolleyCallback(){
@Override
public void onSuccess(String result){
... //do stuff here
}
});
}
You can also make VolleyCallback
more robust, using generic types if you want to do processing, or adding start()
, failed(Exception e)
, complete()
, etc methods to do a little more fine-grained state checking.
Keep in mind this is an async call, so you will have to update views, etc when you get the result back (inside success()
).