Iterators - Data Structures and Abstractions with Java - page 370

15.7

Example. We can use an iterator to display all the entries in a list. The following statements display
the strings in the list nameList , one per line:

Iterator<String> nameIterator = new SeparateIterator<String>(nameList);
while (nameIterator.hasNext())
System.out.println(nameIterator.next());
The iterator nameIterator begins just before the first entry in the list. As long as hasNext returns
true, next returns the next entry in the list and advances the iterator. Thus, every entry in the list is
retrieved and displayed.

15.8

Example. The interface Iterator provides an operation to remove an entry from a data collection.
This entry is the one returned by the last call to the method next . Thus, you must invoke next
before you can call remove .

If nameList contains the strings Andy , Brittany , and Chris , and nameIterator is defined as in
the previous example,

nameIterator.next() returns the string Andy and advances the iterator.

●

nameIterator.next() returns the string Brittany and advances the iterator.

●

nameIterator.remove() removes Brittany from the list.

●

nameIterator.next() returns the string Chris and advances the iterator.

●

Figure 15-3 shows the list during the previous iteration.

FIGURE 15-3

The effect of the iterator methods next and remove on a list

Iterator cursor

Andy
Brittany
Chris

Andy
Brittany
Chris

next() returns Andy and
advances the iterator

Andy
Brittany
Chris

next() returns Brittany and
advances the iterator

Andy
Chris

remove() removes Brittany from the list

Andy
Chris

next() returns Chris and
advances the iterator