Problems with JList

Question

Hi all,
I'm trying to use a JList for a program that I'm making.
To initialize the JList, I use the following code:
public static JList menu;
public MadLibsManagerGui() {
menu = new JList(MadLibsGui.getComboInfo());
the getComboInfo() method returns an array of strings. This should work, no? But, it doesn't seem to be working! When i try printing the number of indices in the jlist, i get -1even though all of my strings (from the array) do get displayed in the JList. Any ideas? Thanks so much! any help is greatly appreciated.
PS. Does anyone know how to close a JFrame using the push of a button?

Answer 1

Even when i pass it an integer constant, i get the
exceptionA couple of things:
First of all, the remove(int) method defined in JList is inherited from java.awt.Container: it is used for removing a child Component with the given index from a Container. In other words, you cannot use it to remove items from the list.
In fact, there are no methods defined in the JList API for adding or removing items once the list is created. This is because the ListModel interface that defines the data that backs the JList is immutable.
It is still possible, of course, to add and remove items from a JList. The trick is to use a custom ListModel implementation, such as DefaultListModel, that allows such modifications. See the JList tutorial for examples of this.
Secondly, if something is selected in the list, getSelectedIndex() will not return -1. If the JList you see on your screen has something selected, but getSelectedIndex() returns -1 when called on a JList reference in your code, then chances are good that you have two different JList objects. The JList that you add to the UI is not the same JList instance you refer to when calling getSelectedIndex().