CODEWITHSUNDEEP
androidparametersandroid-asynctask
GeertG
GeertG

Reputation: 158

Android - Pass extra parameter to AsyncTask

I have a quastion about an AsyncTask, I hope somone could give me some advice. I am performing AsyncTasks to get data from internet. The task is in a separate class. I have multiple AsyncTasks that do exactly the same action, but they get called at different moments and pass data back to different methods. In the current AsyncTask i can exucute it and give one or more url's as parameter.

My question is: is there a way to send an extra parameter to the AsyncTask so that I can use a switch case in the onPostExecute to decide where the webdata should go?

This is one of the AsyncTask classes:

import java.io.BufferedReader;
import java.io.InputStreamReader;

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.protocol.BasicHttpContext;
import org.apache.http.protocol.HttpContext;

import android.os.AsyncTask;
import android.util.Log;

public class GetContactpersoonFromWeb extends AsyncTask<String, Void, String> {
String result = "";
String webData;
FirstScreen activity;

public GetContactpersoonFromWeb(FirstScreen activity)
{
    this.activity = activity;
}


protected String doInBackground(String... urls) {

    HttpClient httpClient = new DefaultHttpClient();
    HttpContext localContext = new BasicHttpContext();
    HttpGet httpGet = new HttpGet(urls[0]);
    HttpResponse response;
    try {
        response = httpClient.execute(httpGet, localContext); 

        BufferedReader reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
        String line = null; //vanaf niks beginnen
        while ((line = reader.readLine()) != null) {
            result += line + "\n"; 
        }   
        this.webData = result;        
    }
    catch (Exception e) {           
        Log.d("info","error bij het ophalen van de data", e);
    }
    return this.webData;            
}

protected void onPostExecute(String result) {
    this.webData = result;
    activity.getContactpersoonData(webData); 
 }

}

The difference with the other AsyncTasks is the last rule: activity.getFabricData(webData); In an other class it is: activity.getMachineData(webData); etc..

Does anyone have an idea how to achieve this by using only 1 class? I think using 7 classes with only 1 rule of diffrence is not the best way.

Thanks in advance!

Upvotes: 0

Views: 774

Answers (3)

Zymurgeek
Zymurgeek

Reputation: 169

@insomniac's answer will work fine, but there's another option to consider. Provided you know where the data needs to go before creating the AsyncTask, another option for different onPostExecute() behavior is to use polymorphism rather than a switch. This allows you to add another type of behavior in the future without the risk of breaking existing code. The technique is explained here: http://sourcemaking.com/refactoring/replace-conditional-with-polymorphism

In your case you'd move the code from GetContactpersoonFromWeb to an abstract base class, say, GetFromWeb, then have GetContactpersoonFromWeb inherit from GetFromWeb and override onPostExecute(). Repeat for FabricData and MachineData.

Upvotes: 0

insomniac
insomniac

Reputation: 11756

You need to create an extra variable in the AsyncTask and add the extra parameter in the constructor like

public GetContactpersoonFromWeb(FirstScreen activity,int extra)

{

this.activity = activity;
    this.extra=extra;

}

Then you can use this value in a switch case like

switch(extra){`
................
.................

Upvotes: 1

Apoorv
Apoorv

Reputation: 13520

Add the date based on which you will perform your switch in your constructor

public GetContactpersoonFromWeb(FirstScreen activity,int yourExtraData)
{
   this.activity = activity;
   mExtraData = extraData;
}

and then use mExtraData in your onPostExecute

Upvotes: 2

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