Here's a test case:

public class Test extends Frame {
 
    java.awt.Panel panel1;
    java.awt.Label label1;
 
    public Test() {
        setLayout(null);
        addNotify();
        resize(insets().left + insets().right
                        + 405,insets().top + insets().bottom + 305);
        panel1 = new java.awt.Panel();
        panel1.setLayout(new CardLayout(0,0));
        panel1.reshape(insets().left + 48,insets().top + 36,295,129);
        add(panel1);
        label1 = new java.awt.Label("text");
        label1.reshape(0,0,295,129);
        panel1.add(label1);
        setTitle("A Basic Application");
    }
 
    static public void main(String args[]) {
        new Frame1();
    }
}


Here's the exception:

java.lang.IllegalArgumentException: cannot add to layout: constraint must be a s
tring
        at java.awt.CardLayout.addLayoutComponent(CardLayout.java:100)
        at java.awt.Container.addImpl(Container.java:278)
        at java.awt.Container.add(Container.java:152)
        at Frame1.<init>(Frame1.java:23)
        at Test.main(Test.java:25)