Iterators - Data Structures and Abstractions with Java - page 396

isRemoveOrSetLegal = false ;
nextIndex++;
ArrayListWithListIterator. this .add(nextIndex, newEntry);
} // end add

FIGURE 15-12

The array of list entries and nextIndex (a) just before the call to
add ; (b) just after the call to add

(a) Before add is called (b) After add("Ben") is called

Art

Art

Bart

Bart

Iterator cursor

Ben

Chris Added entry

nextIndex = 2

Iterator cursor

Chris

Deb

nextIndex = 3

Deb

Elly

Elly

15.49

The method remove . The logic for the remove method when a call to next precedes its call is
somewhat like the logic for the remove method in the interface Iterator , which you saw in
Segment 15.28. Recall that Figure 15-8 illustrated the array of list entries and the index nextIndex
before and after the calls to next and remove . Figure 15-13 provides a similar illustration, showing
what happens when a call to previous precedes the call to remove . In Part b , previous returns a
reference to the previous entry— Bart —in the iteration and decrements nextIndex . The method
remove must remove this entry from the list. Notice that nextIndex is now 1 smaller than the posi-
tion number of the list entry that must be removed. After the entry Bart has been removed in
Figure 15-13c, the next entry— Chris —moves to the next lower-numbered position in the array.
Thus, nextIndex remains the index of the next entry in the iteration and so is unchanged.

FIGURE 15-13

The array of list entries and nextIndex (a) just before the call to
previous ; (b) just after the call to previous but before the call
to remove ; (c) after the call to remove

(a) Before previous() (b) previous() returns Bart (c) remove() removes Bart

Art Art

Art

Iterator cursor

Iterator cursor

nextIndex = 1

Bart Chris

Bart

nextIndex = 1

Iterator cursor

Chris Deb

Chris

nextIndex = 2

Deb Elly

Deb

Elly

Elly