AWT CardLayout Confusion

[chafule razgul]

I made a class as shown to play around with CardLayout

import java.awt.*;
public class mywin extends Frame
{
public mywin()
{
setLayout(new CardLayout());
Button b = new Button("me");
add(b);
//add(b, "2nd"); //works fine..
add(b); 
pack();
setVisible(true);
}
public static void main(String args[])
{
mywin test = new mywin();
}
}

This compiles fine but results in a runtime error:

Exception in thread "main" java.lang.IllegalArgumentException: cannot add to layout: constraint must be a string
        at java.awt.CardLayout.addLayoutComponent(CardLayout.java:151)
        at java.awt.Container.addImpl(Container.java:380)
        at java.awt.Container.add(Container.java:228)
        at mywin.<init>(mywin.java:15)
        at mywin.main(mywin.java:26)  

My problem is, i don't know which add(String, Component) method compiler is referring to. It's not part of the container (I tried Frame vs Panel) nor is it part of the layoutmanager...

[Roy Ben Ami]

when u add components to a container with a cardLayout u need to add them like this:
the name of the component, string to describe it.
exactly like the add u have in comments.
the exception is for the add(b) with no string describing it.
add(Component,String) is the right way for cardLayout.
the reason u need the string is that u can later switch to that card using the name u gave it.