Input dengan JOption pane java class

package oke;
 import javax.swing.JOptionPane;
 public class java {
 public static void main(String[] args){
 String oke;
 oke=JOptionPane.showInputDialog("siapa nama anda ?");
 String msg="hello "+oke+" !";
 JOptionPane.showMessageDialog(null,msg);
              }
 }