public final class Booleans
extends java.lang.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 | Class and Description |
|---|---|
private static class |
Booleans.BooleanArrayAsList |
private static class |
Booleans.BooleanComparator
Comparators for
Boolean values. |
private static class |
Booleans.LexicographicalComparator |
| Modifier | Constructor and Description |
|---|---|
private |
Booleans() |
| Modifier and Type | Method and Description |
|---|---|
static java.util.List<java.lang.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 java.util.Comparator<java.lang.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. |
private static int |
indexOf(boolean[] array,
boolean target,
int start,
int end) |
static java.lang.String |
join(java.lang.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. |
private static int |
lastIndexOf(boolean[] array,
boolean target,
int start,
int end) |
static java.util.Comparator<boolean[]> |
lexicographicalComparator()
Returns a comparator that compares two
boolean arrays lexicographically. |
static void |
reverse(boolean[] array)
Reverses the elements of
array. |
static void |
reverse(boolean[] array,
int fromIndex,
int toIndex)
Reverses the elements of
array between fromIndex inclusive and toIndex
exclusive. |
static boolean[] |
toArray(java.util.Collection<java.lang.Boolean> collection)
Copies a collection of
Boolean instances into a new array of primitive boolean
values. |
static java.util.Comparator<java.lang.Boolean> |
trueFirst()
Returns a
Comparator<Boolean> that sorts true before false. |
public static java.util.Comparator<java.lang.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()).
public static java.util.Comparator<java.lang.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 == bpublic 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 ipublic 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.private static int indexOf(boolean[] array,
boolean target,
int start,
int end)
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 targettarget - the array to search for as a sub-sequence of arraypublic 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.private static int lastIndexOf(boolean[] array,
boolean target,
int start,
int end)
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 minLengthjava.lang.IllegalArgumentException - if minLength or padding is negativepublic static java.lang.String join(java.lang.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 java.util.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(java.util.Collection<java.lang.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 primitivesjava.lang.NullPointerException - if collection or any of its elements is nullpublic static java.util.List<java.lang.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 listpublic static int countTrue(boolean... values)
values that are true.public static void reverse(boolean[] array)
array. This is equivalent to Collections.reverse(Booleans.asList(array)), but is likely to be more efficient.public static void reverse(boolean[] array,
int fromIndex,
int toIndex)
array between fromIndex inclusive and toIndex
exclusive. This is equivalent to Collections.reverse(Booleans.asList(array).subList(fromIndex, toIndex)), but is likely to be
more efficient.java.lang.IndexOutOfBoundsException - if fromIndex < 0, toIndex > array.length, or
toIndex > fromIndex