CODEWITHSUNDEEP
javaandroidruntime-errorprogressdialoglooper
mlevit
mlevit

Reputation: 2736

Can't create handler inside thread that has not called Looper.prepare() inside AsyncTask for ProgressDialog

I don't understand why I'm getting this error. I'm using AsyncTask to run some processes in the background.

I have:

protected void onPreExecute() 
{
    connectionProgressDialog = new ProgressDialog(SetPreference.this);
    connectionProgressDialog.setCancelable(true);
    connectionProgressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
    connectionProgressDialog.setMessage("Connecting to site...");
    connectionProgressDialog.show();

    downloadSpinnerProgressDialog = new ProgressDialog(SetPreference.this);
    downloadSpinnerProgressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
    downloadSpinnerProgressDialog.setMessage("Downloading wallpaper...");
}

When I get into doInBackground() depending on a condition I:

[...]    
connectionProgressDialog.dismiss();
downloadSpinnerProgressDialog.show();
[...]

Whenever I try downloadSpinnerProgressDialog.show() I receive the error.

Any ideas guys?

Upvotes: 78

Views: 100465

Answers (4)

Konstantin Burov
Konstantin Burov

Reputation: 69238

The method show() must be called from the User-Interface (UI) thread, while doInBackground() runs on different thread which is the main reason why AsyncTask was designed.

You have to call show() either in onProgressUpdate() or in onPostExecute().

For example:

class ExampleTask extends AsyncTask<String, String, String> {

    // Your onPreExecute method.

    @Override
    protected String doInBackground(String... params) {
        // Your code.
        if (condition_is_true) {
            this.publishProgress("Show the dialog");
        }
        return "Result";
    }

    @Override
    protected void onProgressUpdate(String... values) {
        super.onProgressUpdate(values);
        connectionProgressDialog.dismiss();
        downloadSpinnerProgressDialog.show();
    }
}

Upvotes: 106

caiocpricci2
caiocpricci2

Reputation: 7798

I had a hard time making this work too, the solution for me was to use both hyui and konstantin answers, 

class ExampleTask extends AsyncTask<String, String, String> {

// Your onPreExecute method.

@Override
protected String doInBackground(String... params) {
    // Your code.
    if (condition_is_true) {
        this.publishProgress("Show the dialog");
    }
    return "Result";
}

@Override
protected void onProgressUpdate(String... values) {

    super.onProgressUpdate(values);
    YourActivity.this.runOnUiThread(new Runnable() {
       public void run() {
           alertDialog.show();
       }
     });
 }

}

Upvotes: 1

jayesh kavathiya
jayesh kavathiya

Reputation: 3541

final Handler handler = new Handler() {
        @Override
        public void handleMessage(final Message msgs) {
        //write your code hear which give error
        }
        }

new Thread(new Runnable() {
    @Override
    public void run() {
    handler.sendEmptyMessage(1);
        //this will call handleMessage function and hendal all error
    }
    }).start();

Upvotes: 0

hyui
hyui

Reputation: 811

I had a similar issue but from reading this question I figured I could run on UI thread:

YourActivity.this.runOnUiThread(new Runnable() {
    public void run() {
        alertDialog.show();
    }
});

Seems to do the trick for me.

Upvotes: 81

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