Java Reference
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The algorithm is similar to optimally looking for a name in a phone book. Start by
openingthebooktotheexactmiddle.Ifthenameisnotonthatpage,proceedtoopen
thebooktotheexactmiddleofthefirsthalforthesecondhalf,dependingoninwhich
half the name occurs. Repeat until you find the name (or not).
Applying a linear search to 4,000,000,000 elements results in approximately
2,000,000,000comparisons(onaverage),whichtakestime.Incontrast,applyingabin-
arysearchto4,000,000,000elementsresultsinamaximumof32comparisons.Thisis
why Arrays contains binarySearch() methodsandnotalso linearSearch()
methods.
Followingisasamplingofthe Collections class'scollection-orientedclassmeth-
ods:
static <T extends Object&Comparable<? super T>> T
min(Collection<? extends T> c) returns the minimum element
ofcollection c according tothe natural ordering ofits elements. Forexample,
System.out.println(Collections.min(Arrays.asList(10,
3, 18, 25))); outputs 3 . All of c 's elements must implement the Com-
parable interface. Furthermore, all elements must be mutually comparable.
This method throws NoSuchElementException when c is empty.
static void reverse(List<?> l) reverses the order of list l 's
elements. For example, List<String> birds = Ar-
rays.asList("Robin", "Oriole", "Bluejay"); Collec-
tions.reverse(birds); System.out.println(birds); results
in [Bluejay, Oriole, Robin] as the output.
static <T> List<T> singletonList(T o) returns an immutable
list containing only object o . For example,
list.removeAll(Collections.singletonList(null)); re-
moves all null elements from list .
static <T> Set<T> synchronizedSet(Set<T> s) returns a
synchronized (thread-safe) set backed by set s ; for example, Set<String>
ss = Collections.synchronizedSet(new
HashSet<String>()); . In order to guarantee serial access, it is critical
that all access to the backing set is accomplished through the returned set.
static <K,V> Map<K,V> unmodifiableMap(Map<? extends
K,? extends V> m) returnsanunmodifiableviewofmap m ;forexample,
Map<String,
Integer>
msi
=
Collec-
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