Question

I currently have multiple activity that needs to perform an asynctask for http post and I wish to make the asynctask as another class file so that the different activity can call the asynctask to perform the http post request and onPostExecute, call the method httpResult(result) in the activity that called the asynctask. I have tried to pass the activity in but I am unable to call the method in onPostExecute. How can I do that?

public class MyActivity extends Activity {
    public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_MyActivity);

    //logic here...
    AsyncHttpPost asyncHttpPost = new AsyncHttpPost("someContent", this, dialog);
    JSONObject data = new JSONObject();
    data.put("key", "value");
    try {
            asyncHttpPost.execute(data);
        }
        catch (Exception ex){
        ex.printStackTrace();
        }
    }
    public static void httpResult(String result) {
        //this method has to get called by asynctask to make changes to the UI
     }

}

AsyncHttpPost.java

public class AsyncHttpPost extends AsyncTask<JSONObject, String, String> {
String recvdjson;
String mData="";
private ProgressDialog dialog;
private Activity activity;


public AsyncHttpPost(String data, Activity activity, ProgressDialog dialog) {
    mData = data;
    this.activity = activity;
    this.dialog = dialog;
}

protected void onPreExecute()
{

    dialog.show();
}

    @Override
    protected String doInBackground(JSONObject... params) {

       //logic to do http request
           return "someStringResult";

    }

    protected void onPostExecute(String result) {
        dialog.dismiss();
        activity.httpResult(result); //This line gives me error : The method httpResult(String) is undefined for the type Activity


    }
}

Answer 1

Create an Interface called HttpResponseImpl in a seperate file and add the required method httpResult

interface HttpResponseImpl{
    public void httpResult(String result);
}

Now implement this interface by you Activity class

public class MyActivity extends Activity implements HttpResponseImpl{

    public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_MyActivity);

    //logic here...
    AsyncHttpPost asyncHttpPost = new AsyncHttpPost("someContent", this, dialog);
    JSONObject data = new JSONObject();
    data.put("key", "value");
    try {
            asyncHttpPost.execute(data);
        }
        catch (Exception ex){
        ex.printStackTrace();
        }
    }

    public void httpResult(String result){
        //this method has to get called by asynctask to make changes to the UI
    }
}

And your AsyncHttpPost class would be.

public class AsyncHttpPost extends AsyncTask<JSONObject, String, String> {
String recvdjson;
String mData="";
private ProgressDialog dialog;
private HttpResponseImpl httpResponseImpl;


public AsyncHttpPost(String data, HttpResponseImpl httpResponseImpl, ProgressDialog dialog) {
    mData = data;
    this.httpResponseImpl = httpResponseImpl;
    this.dialog = dialog;
}

protected void onPreExecute()
{

    dialog.show();
}

    @Override
    protected String doInBackground(JSONObject... params) {

       //logic to do http request
           return "someStringResult";

    }

    protected void onPostExecute(String result) {
        dialog.dismiss();
        httpResponseImpl.httpResult(result); 


    }
}

Implements this HttpResponseImpl interface with all you Activity class from which you want to do HttpRequest.