Question

I am facing one problem in AsyncTask in my application in Android. The problem is, I am starting another Activity from AsyncTask in my application which runs fine when its layout has simple Button, but when I am using ImageButton its giving me error of handler and looper.loop. I am not getting the reason why this kind of error is occurring. I am displaying menus with images in calling Activity.

Can anybody suggest me what is the problem in this and how can I achieve this kind of functionality?

protected void onPostExecute(Void result) {
    super.onPostExecute(result);
    if (Dialog != null && Dialog.isShowing()) {
       Dialog.dismiss();
       locationManager.removeUpdates(locationListener);
       Intent homeIntent = new Intent(ATMActivity.this.getApplicationContext(), HomeMenuActivity.class);
       homeIntent.putExtra("lat", latitude);
       homeIntent.putExtra("lng", longitude);
       startActivity(homeIntent);
    }
}

XML File :-

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical" >

    <ImageButton
        android:id="@+id/imageButton1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/atm_icon"
        android:onClick="buttonClicked" />

</LinearLayout>

Another Activity Class :-

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
       setContentView(R.layout.home);

       Button btn = (Button) findViewById(R.id.imageButton1);
       btn.setHint("ATM");
       float latitude = getIntent().getFloatExtra("lat", 0);
       float longitude = getIntent().getFloatExtra("lng", 0);
       Toast.makeText(getApplicationContext(), "Location Floats:- " + latitude + "," + longitude, Toast.LENGTH_LONG).show();
}

Answer 1

Without the full stack trace it’s hard to say for sure, but my best guess is you’re actually getting a ClassCastException.

Your ATMActivity is trying to cast imageButton1, defined in xml as an ImageButton, to a Button. This is not possible, as the latter is not a superclass of the former.

// Can't do below: Button is not a superclass of ImageButton
Button btn = (Button) findViewById(R.id.imageButton1);

Since you’re starting the activity from the onPostExecute of an AsyncTask, you’ll probably find some stuff mentioning a looper/handler in the stack trace.