Using isFinish() to avoid bad tolken error

gistfile1.txt

android.view.WindowManager$BadTokenException: Unable to add window -- token android.os.BinderProxy@40b47bd8 is not valid; is your activity running?
at android.view.ViewRoot.setView(ViewRoot.java:452)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:283)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:193)
at android.view.WindowManagerImpl$CompatModeWrapper.addView(WindowManagerImpl.java:118)
at android.view.Window$LocalWindowManager.addView(Window.java:532)
at android.app.Dialog.show(Dialog.java:269)
...

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runOnUiThread(new Runnable() {
   @Override
   public void run() {
	if(!isFinishing()){
		showDialog (
			        new AlertDialog.Builder(MainActivity.this)
				.setTitle(R.string.dialogTitle)
				.setMessage(R.string.dialogText)
				.setCancelable(false)
				.setPositiveButton(R.string.txtOk, 
				new OnClickListener() {
					@Override
					public void onClick(DialogInterface dialog, int which) {
                                          // whatever...						
					}
				})
				.create()
			     );
	   }
   }
});