Java Reference
In-Depth Information
FIGURE 12-1
A to-do list
I have so much to do this
weekend — I should make a list.
To Do
1. Read Chapter 12
2. Call home
3. Buy card for Sue
12.1
Everyday lists such as to-do lists, gift lists, address lists, and grocery lists have entries that are
strings. What can you do to such lists?
•
Typically, you
add
a new entry
at the end
of the list.
•
Actually, you can
add
a new entry
anywhere:
at the beginning, the end, or in between items.
•
You can cross out an entry—that is,
remove
it.
•
You can
remove all
entries.
•
You can
replace
an entry.
•
You can
look at
any entry.
•
You can
look at all
of the entries.
•
You can find out whether the list
contains
a particular entry.
•
You can
count
the number of entries in the list.
•
You can see whether the list is
empty
.
When you work with a list, you determine where an entry is or should be. You probably are not
conscious of its exact position: Is it tenth? Fourteenth? However, when your program uses a list, a
convenient way to identify a particular entry is by the entry's position within the list. It could be
first, that is, at position 1, or second (position 2), and so on. This convention allows you to describe,
or specify, the operations on a list more precisely.
VideoNote
The ADT list
12.2
To specify the ADT list, we describe its data and specify the operations on that data. Unlike com-
mon lists whose entries are strings, the ADT list is more general and has entries that are objects of
the same type. The following is an initial specification of the ADT list:
