This interface defines the methods components like JList use
to get the value of each cell in a list and the length of the list.
Logically the model is a vector, indices vary from 0 to
ListDataModel.getSize() - 1. Any change to the contents or
length of the data model must be reported to all of the
ListDataListeners.
Adds a listener to the list that's notified each time a change
to the data model occurs.
Returns the value at the specified index.
Returns the length of the list.
Removes a listener from the list that's notified each time a
change to the data model occurs.