Common class for AsyncTask in Android?

Question

I have a common class say for eg Class A which extends AsyncTask and has all the methods implemented i.e. onPreExecute, doinbackground and onPostExecute.

Now, there are other classes which want to use Class A object.

Say Class B uses class A in the below manner

A a = new A(context)
a.execute(url)

Then i fetch the result in get method. But get method is not the proper way of using AsyncTask. I will like to get the result in onPostExecute. For that i tried using a boolean parameter which will get true only in onpostexecute. The class B will check till it gets true and when it gets true it will fetch the result.

But this is somehow blocking the application.

I have placed the code for asynctask below.

'

import java.io.IOException;

import org.apache.http.client.ClientProtocolException;

import org.apache.http.client.HttpClient;

import org.apache.http.client.ResponseHandler;

import org.apache.http.client.methods.HttpGet;

import org.apache.http.impl.client.BasicResponseHandler;

import org.apache.http.impl.client.DefaultHttpClient;


import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;

public class A extends AsyncTask 
{
private Context context = null;

private final HttpClient httpClient = new DefaultHttpClient();

private String content = null;
//private String error = null;
private String finalResult = null;
private static boolean isResult = false;

private ProgressDialog progressDialog = null; 

public BabbleVilleSyncTask(Context context)
{
    this.context = context; 
    progressDialog = new ProgressDialog(this.context);
}

protected void onPreExecute() 
{
    progressDialog.setMessage("Please Wait....");
    progressDialog.show();
}

protected String doInBackground(String... urls) 
{
    try 
    {
        //urls[0] = URLEncoder.encode(urls[0], "UTF-8");

        HttpGet httpget = new HttpGet(urls[0]);
        ResponseHandler responseHandler = new BasicResponseHandler();
        content = httpClient.execute(httpget, responseHandler);
    }
    /*catch(UnsupportedEncodingException ue)
    {
        error = ue.getMessage();
    }*/
    catch (ClientProtocolException e) 
    {
        //error = e.getMessage();
        cancel(true);
    }
    catch (IOException e) 
    {
        //error = e.getMessage();
        cancel(true);
    }

    httpClient.getConnectionManager().shutdown();

    return content;
}

protected void onPostExecute(String result) 
{
    finalResult = result;
    progressDialog.dismiss();
    System.out.println("on Post execute called");
    isResult = true;
}  

public boolean getIsResult()
{
    return isResult;
}

public void setIsResult(boolean flag)
{
    isResult = flag;
}

public String getResult()
{
    return finalResult;
}
}

'

Can someone let me know what the issue may be?

Regards

Sunil

user_423868 · Answer

public abstract class BaseTask extends AsyncTask {

    public Context context;
    public ProgressDialog dialog;
    public Exception exception;

    protected BaseTask() {
    }

    public BaseTask(Context context) {
        this.context = context;
        this.dialog = new ProgressDialog(context);
    }

    @Override
    protected void onPreExecute() {
        this.dialog.setMessage(context.getResources().getString(R.string.loading));
        this.dialog.show();
    }

    @Override
    protected T doInBackground(Object... objects) {
        try {
           return doWork(objects);
        } catch (Exception e) {
            exception = e;
        }
        return null;
    }

    @Override
    protected void onPostExecute(T result) {
        if (dialog.isShowing()) dialog.dismiss();
        if (exception == null) {
            onResult(result);
        } else {
           onError();
        }
    }



    public abstract T doWork(Object... objects) throws Exception;
    public abstract void onResult(T result);
    public abstract void onError();



}

Common class for AsyncTask in Android?

3 Answers