Question

I have problem showing AlertDialog. Whenever I run the code, the application become not responding and force close. Herewith my code:

public void displayList(View view){

     new AsyncTask<String, Void, List<Address>>() {

          protected List<Address> doInBackground(String... params) {
               /*  some operations  */
               return null;
          }

          protected void onPostExecute(List<Address> result) {
               if(result.size() == 0){
                    /*  do something  */
               } else {

                    /*  some code  */

                    AlertDialog.Builder alert = new AlertDialog.Builder(this);
                    alert.setMessage(sometext);
                    alert.show();
               }
          }

     }.execute(destination);

}

and here is my logCat

11-20 20:26:56.848: E/AndroidRuntime(29789): FATAL EXCEPTION: main
11-20 20:26:56.848: E/AndroidRuntime(29789): java.lang.NullPointerException
11-20 20:26:56.848: E/AndroidRuntime(29789):    at android.app.AlertDialog.resolveDialogTheme(AlertDialog.java:142)
11-20 20:26:56.848: E/AndroidRuntime(29789):    at android.app.AlertDialog$Builder.(AlertDialog.java:359)
11-20 20:26:56.848: E/AndroidRuntime(29789):    at com.ceria.tuntun.MainActivity$5.onPostExecute(MainActivity.java:201)
11-20 20:26:56.848: E/AndroidRuntime(29789):    at com.ceria.tuntun.MainActivity$5.onPostExecute(MainActivity.java:1)
11-20 20:26:56.848: E/AndroidRuntime(29789):    at android.os.AsyncTask.finish(AsyncTask.java:602)
11-20 20:26:56.848: E/AndroidRuntime(29789):    at android.os.AsyncTask.access$600(AsyncTask.java:156)
11-20 20:26:56.848: E/AndroidRuntime(29789):    at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:615)
11-20 20:26:56.848: E/AndroidRuntime(29789):    at android.os.Handler.dispatchMessage(Handler.java:99)
11-20 20:26:56.848: E/AndroidRuntime(29789):    at android.os.Looper.loop(Looper.java:137)
11-20 20:26:56.848: E/AndroidRuntime(29789):    at android.app.ActivityThread.main(ActivityThread.java:4511)
11-20 20:26:56.848: E/AndroidRuntime(29789):    at java.lang.reflect.Method.invokeNative(Native Method)
11-20 20:26:56.848: E/AndroidRuntime(29789):    at java.lang.reflect.Method.invoke(Method.java:511)
11-20 20:26:56.848: E/AndroidRuntime(29789):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:980)
11-20 20:26:56.848: E/AndroidRuntime(29789):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:747)
11-20 20:26:56.848: E/AndroidRuntime(29789):    at dalvik.system.NativeStart.main(Native Method)

I don’t know what this happen. I have used AlertDialog so many times and wonder why this one can’t work.

Thank you

Answer 1

use this..

AlertDialog.Builder alert = new AlertDialog.Builder(yourActivity.this);

and if you using AlertDialog in TabHost use below line..

AlertDialog.Builder alert = new AlertDialog.Builder(getParent());