Java Reference
In-Depth Information
40
System.out.print(
"The list is: "
);
41
42
for
(Character element : listRef)
43
System.out.printf(
"%s "
, element);
44
45
Collections.max(listRef)
Collections.min(listRef)
System.out.printf(
"%nMax: %s"
,
);
46
System.out.printf(
" Min: %s%n"
,
);
47
}
48
}
// end class Algorithms1
list contains:
The list is: P C M
Max: P Min: C
After calling reverse, list contains:
The list is: M C P
Max: P Min: C
After copying, copyList contains:
The list is: M C P
Max: P Min: C
After calling fill, list contains:
The list is: R R R
Max: R Min: R
Fig. 16.11
|
Collections
methods
reverse
,
fill
,
copy
,
max
and
min
. (Part 2 of 2.)
Line 13 creates
List<Character>
variable
list
and initializes it with a
List
view of
the
Character
array
letters
. Lines 14-15 output the current contents of the
List
. Line
18 calls
Collections
method
reverse
to reverse the order of
list
. Method
reverse
takes
one
List
argument. Since
list
is a
List
view of array
letters
, the array's elements are
now in reverse order. The reversed contents are output in lines 19-20. Line 27 uses
Col-
lections
method
copy
to copy
list
's elements into
copyList
. Changes to
copyList
do
not change
letters
, because
copyList
is a separate
List
that's not a
List
view of the array
letters
. Method
copy
requires two
List
arguments—the destination
List
and the
source
List
. Line 32 calls
Collections
method
fill
to place the character
'R'
in each
list
element. Because
list
is a
List
view of the array
letters
, this operation changes
each element in
letters
to
'R'
. Method
fill
requires a
List
for the first argument and
an
Object
for the second argument—in this case, the
Object
is the
boxed
version of the
character
'R'
. Lines 45-46 call
Collections
methods
max
and
min
to find the largest and
the smallest element of a
Collection
, respectively. Recall that interface
List
extends
interface
Collection
, so a
List
is a
Collection
.
The high-speed binary search algorithm—which we discuss in detail in Section 19.4—is
built into the Java collections framework as a
static
Collections
method
binarySearch
.
This method locates an object in a
List
(e.g., a
LinkedList
or an
ArrayList
). If the object
is found, its index is returned. If the object is not found,
binarySearch
returns a negative
