import javax.swing.JOptionPane;
public class Main {
public static void main(String[] args) {
String inputValue = JOptionPane.showInputDialog("Please input a value");
if (inputValue == null) {
System.out.println("CANCEL");
} else if (inputValue.equals("")) {
System.out.println("OK");
} else {
JOptionPane.showMessageDialog(null, inputValue);
}
}
}