Reputation: 129
My java skills are quite good, still I fail to grasp what happens here. I am programming an android app and right now I am programming a class which uses the Google Volley API in order to interact with a web-server. The problem is that I want the class to be called like this:
Server_interaction s_i = new Server_interaction(getApplication);
String text = s_i.post_request();
Text should now contain the returned post request, in my case the string "Hello from server". Instead, it turns out to be null. This happens because the post_request method seems to return before having executed the post_request.
Here is the Server_interaction class:
public class Server_interaction
{
String server_url = "someipadress/greeting.php"; //this address is correct, but I want to hide it for you guys :)
String response_string;
Context myContext;
RequestQueue requestQueue;
public static final String TAG = Server_interaction.class.getSimpleName();
/* Here we add a constructor that takes in context. We need a context for volley requestqueue, and this is an elegant way*/
public Server_interaction(Context context)
{
myContext = context;
requestQueue = Volley.newRequestQueue(myContext);
}
public String post_request()
{
StringRequest stringRequest = new StringRequest(Request.Method.POST, server_url,
new Response.Listener<String>()
{
@Override
public void onResponse(String response)
{
response_string = response;
requestQueue.stop();
Log.i(TAG, "the response is: "+ response_string);
}
}
, new Response.ErrorListener()
{
@Override
public void onErrorResponse(VolleyError error)
{
response_string = "Something went wrong";
//error.printstacktrace()
requestQueue.stop();
}
}
); //stringrequest parameter end
//add request to requestqueue
requestQueue.add(stringRequest);
Log.i(TAG, "the response again:: "+ response_string);
return response_string;
}
}
When being executed, logcat shows this:
01-22 19:00:44.878 2954-2954/com.example.koenraad.Exigentia I/Server_interaction: the response again:: null
01-22 19:00:44.926 2954-2954/com.example.koenraad.Exigentia I/Server_interaction: the response is: hello from server
So this means that the string is null when being returned, then afterwards it is set. How can this be fixed?
Thanks in advance!
Upvotes: 0
Views: 59
Reputation: 14883
Your code is asynchrounous.
The StringRequest
object created in method post_request()
will be used by the framework after the method returns.
Upvotes: 2