error FATAL EXCEPTION: AsyncTask #1 android

Question

I'm doing a program for android that check in my database if exists rows in a table named sms. If so, then get the number, the text and the id and send the message.

However, there is an error that I can not understand. I'm using this code to check on the database:

public class AsyncTaskParseJson extends AsyncTask<String, String, String> {

    TextView tres = (TextView) findViewById(R.id.txtresult);
    final String TAG = "AsyncTaskParseJson.java";

    // set your json string url here
    String yourJsonStringUrl= "http://192.168.1.7/aplicacao_sms/load_sms.php";
    //String yourJsonStringUrl = "http://demo.codeofaninja.com/tutorials/json-example-with-php/index.php";
    // contacts JSONArray
    JSONArray dataJsonArr = null;

    @Override
    protected void onPreExecute() {}

    @Override
    protected String doInBackground(String... arg0) {


        try {



            // instantiate our json parser
            JsonParser jParser = new JsonParser();

            // get json string from url
            JSONObject json = jParser.getJSONFromUrl(yourJsonStringUrl);

            // get the array of users
            dataJsonArr = json.getJSONArray("products");

            // loop through all users

            for (int i = 0; i < dataJsonArr.length(); i++) {
                JSONObject c = dataJsonArr.getJSONObject(i);
                String id=c.getString("id");
                String numero=c.getString("numero");
                String msg=c.getString("msg");


                send_sms(numero, msg, id);

            }
            dataJsonArr = json.getJSONArray("products");
            JSONObject c = dataJsonArr.getJSONObject(0);

        } catch (JSONException e) {
            e.printStackTrace();
        }

        return null;
    }

    @Override
    protected void onPostExecute(String strFromDoInBg) {}
}

and when executing that's the error:

 08-17 14:13:39.993    7781-7794/pt.styledesign.outro_teste W/dalvikvm﹕ threadid=11: thread exiting with uncaught exception (group=0x40de22a0)
08-17 14:13:40.393    7781-7794/pt.styledesign.outro_teste E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #1
    java.lang.RuntimeException: An error occured while executing doInBackground()
            at android.os.AsyncTask$3.done(AsyncTask.java:299)
            at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
            at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
            at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
            at java.util.concurrent.FutureTask.run(FutureTask.java:137)
            at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
            at java.lang.Thread.run(Thread.java:856)
     Caused by: android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
            at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:5083)
            at android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:976)
            at android.view.View.requestLayout(View.java:15520)
            at android.view.View.requestLayout(View.java:15520)
            at android.view.View.requestLayout(View.java:15520)
            at android.view.View.requestLayout(View.java:15520)
            at android.widget.RelativeLayout.requestLayout(RelativeLayout.java:292)
            at android.view.View.requestLayout(View.java:15520)
            at android.widget.ScrollView.requestLayout(ScrollView.java:1711)
            at android.view.View.requestLayout(View.java:15520)
            at android.widget.TextView.checkForResize(TextView.java:6677)
            at android.widget.TextView.updateAfterEdit(TextView.java:7575)
            at android.widget.TextView.handleTextChanged(TextView.java:7585)
            at android.widget.TextView$ChangeWatcher.onTextChanged(TextView.java:9371)
            at android.text.SpannableStringBuilder.sendTextChanged(SpannableStringBuilder.java:964)
            at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:498)
            at android.text.SpannableStringBuilder.append(SpannableStringBuilder.java:253)
            at android.text.SpannableStringBuilder.append(SpannableStringBuilder.java:30)
            at android.widget.TextView.append(TextView.java:3367)
            at android.widget.TextView.append(TextView.java:3354)
            at pt.styledesign.outro_teste.MainActivity.send_sms(MainActivity.java:189)
            at pt.styledesign.outro_teste.MainActivity.access$000(MainActivity.java:23)
            at pt.styledesign.outro_teste.MainActivity$AsyncTaskParseJson.doInBackground(MainActivity.java:87)
            at pt.styledesign.outro_teste.MainActivity$AsyncTaskParseJson.doInBackground(MainActivity.java:47)
            at android.os.AsyncTask$2.call(AsyncTask.java:287)
            at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
            at java.util.concurrent.FutureTask.run(FutureTask.java:137)
            at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
            at java.lang.Thread.run(Thread.java:856)

can anyone help me?

Answer 1

You can get this exception because Your are updating your UI in doInBackground() method.

Change your AsyncTask like this.

public class AsyncTaskParseJson extends AsyncTask<String, Void, JSONObject> {

    TextView tres = (TextView) findViewById(R.id.txtresult);
    final String TAG = "AsyncTaskParseJson.java";

    // set your json string url here
    String yourJsonStringUrl= "http://192.168.1.7/aplicacao_sms/load_sms.php";
    //String yourJsonStringUrl = "http://demo.codeofaninja.com/tutorials/json-example-with-php/index.php";
    // contacts JSONArray
    JSONArray dataJsonArr = null;

    @Override
    protected void onPreExecute() {}

    @Override
    protected JSONObject doInBackground(String... arg0) {

        try {
            // instantiate our json parser
            JsonParser jParser = new JsonParser();

            // get json string from url
            JSONObject json = jParser.getJSONFromUrl(yourJsonStringUrl);
            return json;
        } catch (JSONException e) {
            e.printStackTrace();
        }

        return null;
    }

    @Override
    protected void onPostExecute(JSONObject json) {
          try {

            // get the array of users
            dataJsonArr = json.getJSONArray("products");

            // loop through all users

            for (int i = 0; i < dataJsonArr.length(); i++) {
                JSONObject c = dataJsonArr.getJSONObject(i);
                String id=c.getString("id");
                String numero=c.getString("numero");
                String msg=c.getString("msg");
                send_sms(numero, msg, id);

            }
            dataJsonArr = json.getJSONArray("products");
            JSONObject c = dataJsonArr.getJSONObject(0);

        } catch (JSONException e) {
            e.printStackTrace();
        }
  }
}

I hope it helps!

Answer 2

Your problem is caused by this:

android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.

You can't access any UI element from the doInBackground() method. The safe way to do this is by using the methods publishProgress() and onPostExecute().

So you will probably need to wrap the parameters from send_sms() into a new object, post it in publishProgress() and then you can update TextView tres on the onProgressUpdate() method.