title: finish activity from non activity
body: <p>I am developing an app. I want to call a alert dialog from 1st activity. The alert dialog is written in another class which is a non activity class. The need of application is that the calling activity should finish from alert which is written in non activity class. The code of calling the alert is as below.</p>
  
  <p>Calling the alert from 1st activity: </p>
  
  <pre><code>public class Activity1 extends Activity {
      /** Called when the activity is first created. */
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.list_layout);
      }// End of onCreate.
  
          /** Back Button. */
      @Override
      public boolean onKeyDown(int keyCode, KeyEvent event) {
          if (keyCode == KeyEvent.KEYCODE_BACK) {
              String message = "Do you Want to Exit.";
              Utility.callAlert(message, getApplicationContext());
              return true;
          }
          return super.onKeyDown(keyCode, event);
      }   
  }
  </code></pre>
  
  <p>And the called class having alert dialog is : </p>
  
  <pre><code>public class Utility {
      // callAlert method to display alert, when exception occur.
      public static void callAlert(String message, final Context context){
          AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(context);
          alertDialogBuilder.setTitle("MyApplication.");
          alertDialogBuilder.setMessage(message);
          alertDialogBuilder.setNeutralButton("Ok", new DialogInterface.OnClickListener() {                   
  
              public void onClick(DialogInterface dialog, int which) {
                  ((Activity1)context.getApplicationContext()).finish();
              } //end onClick.
          }); // end alertDialog.setButton.
          alertDialogBuilder.show();  
      }
  }
  </code></pre>
  
  <p>But this gives me the error as : </p>
  
  <pre><code>02-25 17:00:45.961: D/AndroidRuntime(444): Shutting down VM
  02-25 17:00:45.961: W/dalvikvm(444): threadid=1: thread exiting with uncaught exception (group=0x40015560)
  02-25 17:00:45.971: E/AndroidRuntime(444): FATAL EXCEPTION: main
  02-25 17:00:45.971: E/AndroidRuntime(444): android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
  02-25 17:00:45.971: E/AndroidRuntime(444):  at android.view.ViewRoot.setView(ViewRoot.java:531)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:177)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at android.app.Dialog.show(Dialog.java:241)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at android.app.AlertDialog$Builder.show(AlertDialog.java:802)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at com.xxx.myapp.specialclasses.Utility.callAlert(Utility.java:25)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at com.xxx.myapp.activities.Activity1.onKeyDown(Activity1.java:149)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at android.view.KeyEvent.dispatch(KeyEvent.java:1256)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at android.app.Activity.dispatchKeyEvent(Activity.java:2078)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1663)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at android.view.ViewRoot.deliverKeyEventToViewHierarchy(ViewRoot.java:2560)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at android.view.ViewRoot.handleFinishedEvent(ViewRoot.java:2535)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at android.view.ViewRoot.handleMessage(ViewRoot.java:1867)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at android.os.Handler.dispatchMessage(Handler.java:99)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at android.os.Looper.loop(Looper.java:123)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at android.app.ActivityThread.main(ActivityThread.java:3683)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at java.lang.reflect.Method.invokeNative(Native Method)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at java.lang.reflect.Method.invoke(Method.java:507)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
  02-25 17:00:45.971: E/AndroidRuntime(444):  at dalvik.system.NativeStart.main(Native Method)
  02-25 17:05:46.061: I/Process(444): Sending signal. PID: 444 SIG: 9
  </code></pre>