My Android app has a dialog with possitive button and 3 radio button.  

2 of 3 are wrong answer and 1 is correct answer.  

When user select wrong answer and press possitiveButton as OK,  

I don't want to dismiss the dialog and display toast message to say   

your choice is incorrect.  

Then user can re-select another answer and press OK,  

if the answer is correct, I want to dismiss the dialog.  

I'd like to know how not to dismiss the dialog when possitiveButton is pressed.  

Thanks!