The collections api - Data Structures and Problem Solving Using Java - page 245

39 /**
40 * Returns the maximum object in the collection,
41 * using default ordering
42 * @param coll the collection.
43 * @return the maximum object.
44 * @throws NoSuchElementException if coll is empty.
45 * @throws ClassCastException if objects in collection
46 * cannot be compared.
47 */
48 public static <AnyType extends Object & Comparable<? super AnyType>>
49 AnyType max( Collection<? extends AnyType> coll )
50 {
51 return max( coll, new DefaultComparator<AnyType>( ) );
52 }
53
54 /**
55 * Returns the maximum object in the collection.
56 * @param coll the collection.
57 * @param cmp the comparator.
58 * @return the maximum object.
59 * @throws NoSuchElementException if coll is empty.
60 * @throws ClassCastException if objects in collection
61 * cannot be compared.
62 */
63 public static <AnyType>
64 AnyType max( Collection<? extends AnyType> coll, Comparator<? super AnyType> cmp )
65 {
66 if( coll.size( ) == 0 )
67 throw new NoSuchElementException( );
68
69 Iterator<? extends AnyType> itr = coll.iterator( );
70 AnyType maxValue = itr.next( );
71
72 while( itr.hasNext( ) )
73 {
74 AnyType current = itr.next( );
75 if( cmp.compare( current, maxValue ) > 0 )
76 maxValue = current;
77 }
78
79 return maxValue;
80 }

81 }

figure 6.14
The Collections class (part 2): max

by supplying the default comparator. The funky syntax in the type param-
eter list is used to ensure that the type erasure of max generates Object
(rather than Comparable ). This is important because earlier versions of Java