秋千CardLayout

Question

What is the default behavior of cardlayout when you add two cards with same identifier. For example, if have panel1 which is added. Later in the program, I add panel2 with the same string identifier. Is the default behavior to replace panel1 with panel2 in the card stack? Thanks

Answer 1

Below is CardLayout's implementation of addLayoutComponent() which is executed by addLayoutComponent(Component comp, Object constraints) .

public void addLayoutComponent(String name, Component comp) {
    synchronized (comp.getTreeLock()) {
        if (!vector.isEmpty()) {
            comp.setVisible(false);
        }
        for (int i=0; i < vector.size(); i++) {
            if (((Card)vector.get(i)).name.equals(name)) {
                ((Card)vector.get(i)).comp = comp;
                return;
            }
        }
        vector.add(new Card(name, comp));
    }
}

CardLayout maintains a vector of Card objects (see below). Looks like when a name collision is detected, the Component in the Card with the same name is replaced with new Component being added. So, show() with a particular name will display the last component that was added with that name.

class Card implements Serializable {
    static final long serialVersionUID = 6640330810709497518L;
    public String name;
    public Component comp;
    public Card(String cardName, Component cardComponent) {
        name = cardName;
        comp = cardComponent;
    }
}

Answer 2

You can add multiple cards with the same identifier. You can [edit] only still [/edit] navigate to both . show(Container, String) shows the panel added [edit] first last [/edit].

Kasper