@GwtCompatible public final class Booleans extends Object
boolean
primitives, that are not already found in
either Boolean
or Arrays
.
See the Guava User Guide article on primitive utilities.
Modifier and Type | Method and Description |
---|---|
static List<Boolean> |
asList(boolean... backingArray)
Returns a fixed-size list backed by the specified array, similar to
Arrays.asList(Object[]) . |
static int |
compare(boolean a,
boolean b)
Compares the two specified
boolean values in the standard way (false is
considered less than true ). |
static boolean[] |
concat(boolean[]... arrays)
Returns the values from each provided array combined into a single array.
|
static boolean |
contains(boolean[] array,
boolean target)
Returns
true if target is present as an element anywhere in array . |
static int |
countTrue(boolean... values)
Returns the number of
values that are true . |
static boolean[] |
ensureCapacity(boolean[] array,
int minLength,
int padding)
Returns an array containing the same values as
array , but guaranteed to be of a
specified minimum length. |
static Comparator<Boolean> |
falseFirst()
Returns a
Comparator<Boolean> that sorts false before true . |
static int |
hashCode(boolean value)
Returns a hash code for
value ; equal to the result of invoking
((Boolean) value).hashCode() . |
static int |
indexOf(boolean[] array,
boolean target)
Returns the index of the first appearance of the value
target in array . |
static int |
indexOf(boolean[] array,
boolean[] target)
Returns the start position of the first occurrence of the specified
target within array , or -1 if there is no such occurrence. |
static String |
join(String separator,
boolean... array)
Returns a string containing the supplied
boolean values separated by separator . |
static int |
lastIndexOf(boolean[] array,
boolean target)
Returns the index of the last appearance of the value
target in array . |
static Comparator<boolean[]> |
lexicographicalComparator()
Returns a comparator that compares two
boolean arrays lexicographically. |
static boolean[] |
toArray(Collection<Boolean> collection)
Copies a collection of
Boolean instances into a new array of primitive boolean
values. |
static Comparator<Boolean> |
trueFirst()
Returns a
Comparator<Boolean> that sorts true before false . |
@Beta public static Comparator<Boolean> trueFirst()
Comparator<Boolean>
that sorts true
before false
.
This is particularly useful in Java 8+ in combination with Comparators.comparing
,
e.g. Comparators.comparing(Foo::hasBar, trueFirst())
.
@Beta public static Comparator<Boolean> falseFirst()
Comparator<Boolean>
that sorts false
before true
.
This is particularly useful in Java 8+ in combination with Comparators.comparing
,
e.g. Comparators.comparing(Foo::hasBar, falseFirst())
.
public static int hashCode(boolean value)
value
; equal to the result of invoking
((Boolean) value).hashCode()
.
Java 8 users: use Boolean.hashCode(boolean)
instead.
value
- a primitive boolean
valuepublic static int compare(boolean a, boolean b)
boolean
values in the standard way (false
is
considered less than true
). The sign of the value returned is the same as that of
((Boolean) a).compareTo(b)
.
Note for Java 7 and later: this method should be treated as deprecated; use the
equivalent Boolean.compare(boolean, boolean)
method instead.
a
- the first boolean
to compareb
- the second boolean
to comparea
is true
, a negative number if only
b
is true, or zero if a == b
public static boolean contains(boolean[] array, boolean target)
true
if target
is present as an element anywhere in array
.
Note: consider representing the array as a BitSet
instead,
replacing Booleans.contains(array, true)
with !bitSet.isEmpty()
and
Booleans.contains(array, false)
with bitSet.nextClearBit(0) == sizeOfBitSet
.
array
- an array of boolean
values, possibly emptytarget
- a primitive boolean
valuetrue
if array[i] == target
for some value of i
public static int indexOf(boolean[] array, boolean target)
target
in array
.
Note: consider representing the array as a BitSet
instead, and
using BitSet.nextSetBit(int)
or BitSet.nextClearBit(int)
.
array
- an array of boolean
values, possibly emptytarget
- a primitive boolean
valuei
for which array[i] == target
, or -1
if no
such index exists.public static int indexOf(boolean[] array, boolean[] target)
target
within array
, or -1
if there is no such occurrence.
More formally, returns the lowest index i
such that Arrays.copyOfRange(array, i, i + target.length)
contains exactly the same elements as
target
.
array
- the array to search for the sequence target
target
- the array to search for as a sub-sequence of array
public static int lastIndexOf(boolean[] array, boolean target)
target
in array
.array
- an array of boolean
values, possibly emptytarget
- a primitive boolean
valuei
for which array[i] == target
, or -1
if no
such index exists.public static boolean[] concat(boolean[]... arrays)
concat(new boolean[] {a, b}, new boolean[] {}, new boolean[] {c}
returns the array
{a, b, c}
.arrays
- zero or more boolean
arrayspublic static boolean[] ensureCapacity(boolean[] array, int minLength, int padding)
array
, but guaranteed to be of a
specified minimum length. If array
already has a length of at least minLength
,
it is returned directly. Otherwise, a new array of size minLength + padding
is
returned, containing the values of array
, and zeroes in the remaining places.array
- the source arrayminLength
- the minimum length the returned array must guaranteepadding
- an extra amount to "grow" the array by if growth is necessaryarray
, with guaranteed minimum length
minLength
IllegalArgumentException
- if minLength
or padding
is negativepublic static String join(String separator, boolean... array)
boolean
values separated by separator
.
For example, join("-", false, true, false)
returns the string
"false-true-false"
.separator
- the text that should appear between consecutive values in the resulting string
(but not at the start or end)array
- an array of boolean
values, possibly emptypublic static Comparator<boolean[]> lexicographicalComparator()
boolean
arrays lexicographically. That is, it
compares, using compare(boolean, boolean)
), the first pair of values that follow any
common prefix, or when one array is a prefix of the other, treats the shorter array as the
lesser. For example, [] < [false] < [false, true] < [true]
.
The returned comparator is inconsistent with Object.equals(Object)
(since arrays
support only identity equality), but it is consistent with
Arrays.equals(boolean[], boolean[])
.
public static boolean[] toArray(Collection<Boolean> collection)
Boolean
instances into a new array of primitive boolean
values.
Elements are copied from the argument collection as if by collection.toArray()
. Calling this method is as thread-safe as calling that method.
Note: consider representing the collection as a BitSet
instead.
collection
- a collection of Boolean
objectscollection
, in the same order, converted
to primitivesNullPointerException
- if collection
or any of its elements is nullpublic static List<Boolean> asList(boolean... backingArray)
Arrays.asList(Object[])
. The list supports List.set(int, Object)
, but any
attempt to set a value to null
will result in a NullPointerException
.
The returned list maintains the values, but not the identities, of Boolean
objects
written to or read from it. For example, whether list.get(0) == list.get(0)
is true for
the returned list is unspecified.
backingArray
- the array to back the listCopyright © 2010-2017. All Rights Reserved.