How to instantiate AsyncTask

Question

package com.markana.yamba;

import winterwell.jtwitter.Twitter;
import winterwell.jtwitter.TwitterException;
import android.app.Activity;
import android.graphics.Color;
import android.os.AsyncTask;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class StatusActivity2 extends Activity implements OnClickListener{
    private static final String TAG= "StatusActivity";
    EditText editText;
    Button updateButton;
    TextView textCount;
    Twitter twitter;


    /** Called when the activity is first created. */
    @SuppressWarnings("deprecation")
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.status);
        //Finds views
        editText =(EditText) findViewById(R.id.editText);
        updateButton=(Button) findViewById(R.id.buttonUpdate);
        updateButton.setOnClickListener(this);



        twitter=new Twitter("student","password");
        twitter.setAPIRootUrl(("http://yamba.marakana.com/api"));   

    }

    public void onClick(View arg0) {
        // TODO Auto-generated method stub
        String status=editText.getText().toString();
        new PostToTwitter().execute(status);
        Log.d(TAG, "onClick");
    }

    class PostToTwitter extends AsyncTask<String,Integer, String>
    {
        @Override
        protected String doInBackground(String... statuses) {

            try{
            Twitter.Status status=twitter.updateStatus(statuses[0]);
            return status.text;
            }
            catch(TwitterException e)
            {
                Log.e(TAG,e.toString());
                e.printStackTrace();
                return "Failed to post";
            }
        }


        protected void onProgressUpdate(Integer...values)
        {
               super.onProgressUpdate(values);
        }

        protected void onPostExecute(String result)
        {
            Toast.makeText(StatusActivity2.this,result,Toast.LENGTH_LONG).show();           
        }
    }





}

i get two exceptions relating to Async task

thats what i did. it tells me that i have a problem when i run the background worker!!

04-20 09:21:32.553: ERROR/AndroidRuntime(838): FATAL EXCEPTION: AsyncTask #1
04-20 09:21:32.553: ERROR/AndroidRuntime(838): java.lang.RuntimeException: An error occured while executing doInBackground()
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     at android.os.AsyncTask$3.done(AsyncTask.java:200)
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     at java.util.concurrent.FutureTask.run(FutureTask.java:137)
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     at java.lang.Thread.run(Thread.java:1096)
04-20 09:21:32.553: ERROR/AndroidRuntime(838): Caused by: java.lang.IllegalArgumentException
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     at java.util.Date.parse(Date.java:447)
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     at java.util.Date.<init>(Date.java:157)
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     at winterwell.jtwitter.Twitter$Status.<init>(Twitter.java:659)
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     at winterwell.jtwitter.Twitter.updateStatus(Twitter.java:3231)
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     at winterwell.jtwitter.Twitter.updateStatus(Twitter.java:3161)
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     at com.markana.yamba.StatusActivity2$PostToTwitter.doInBackground(StatusActivity2.java:60)
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     at com.markana.yamba.StatusActivity2$PostToTwitter.doInBackground(StatusActivity2.java:1)
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     at android.os.AsyncTask$2.call(AsyncTask.java:185)
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
04-20 09:21:32.553: ERROR/AndroidRuntime(838):     ... 4 more

it should pop a message in the end.. as you can see in the method onClick!

Answer 1

I don't think it has anything to do with AsyncTask or Context. The below line is failing which is doing some date parsing. Can you try calling below in a main thread without AsyncTask and see if it is working?.

Twitter.Status status=twitter.updateStatus(statuses[0]);

Answer 2

Twitter.java:659

are you using some date creation here ? looks like you are parsing a string to date object and string is not in the date format specified.

below is ur problem part. nothing to do with task creation i guess.what format is 04-20 09:21:32.553

i guess it should be somewat like mm-dd-yy hh:mm:ss.nnn or some other standard format

Caused by: java.lang.IllegalArgumentException 04-20 09:21:32.553: ERROR/AndroidRuntime(838): at java.util.Date.parse(Date.java:447) 04-20 09:21:32.553: ERROR/AndroidRuntime(838): at java.util.Date.<init>(Date.java:157) 04-20 09:21:32.553: ERROR/AndroidRuntime(838): at winterwell.jtwitter.Twitter$Status.<init>(Twitter.java:659) 04-20 09:21:32.553: ERROR/AndroidRuntime(838): at winterwell.jtwitter.Twitter.updateStatus(Twitter.java:3231)

Answer 3

It may be that the

Toast.makeText(StatusActivity2.this,res..

fails, as the context you pass in is not valid.

Try to pass in the Context in the Constructor of PostToTwitter, store it locally and then use this instance when creating the Toast.

See e.g. here for the call, here for the Constructor and here for the onPostExecute

Answer 4

Assuming I understand properly: update your screen in the onPostExecute method. You might want to have a member variable of your activity holding the current task. The in your onClick function, simply check if a task is already running before creating a new one.

Also, don't forget to remove the click listener when you destroy your activity, else you will leak memory.

protected void onDestroy() {
  updateButton.setOnClickListener(null);
  super.onDestroy();
}