Inconvertible types error in java

I have the following code:

                import javax.swing.JOptionPane;

            public class Excercise613
            {
                /** Display the prompt to the user; wait for the user to enter
                  *  a whole number; return it.  */

                 public static int askInt(String prompt)
                 {    
                     String s = JOptionPane.showInputDialog(prompt);
                     Double d = Double.parseDouble(s);
                     return d >= 0 ? (int) d : (int) (d - 1);
                 } // End of method
            } // End of class

When I compile this, I get an error at the bottom of the screen that says "inconvertible types. required: int; found: java.lang.Double" And then it highlights the "(int) d" piece of code.

What am I doing wrong here? Why isn't the type casting working?