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java.lang.Objectcom.google.common.primitives.Booleans
@GwtCompatible public final class Booleans
Static utility methods pertaining to boolean primitives, that are not
already found in either Boolean or Arrays.
| Method Summary | |
|---|---|
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 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 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. |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Method Detail |
|---|
public static int hashCode(boolean value)
value; equal to the result of invoking
((Boolean) value).hashCode().
value - a primitive boolean value
public 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).
a - the first boolean to compareb - the second boolean to compare
a 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 value
true 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 value
i 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 java.util.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 array
public static int lastIndexOf(boolean[] array,
boolean target)
target in
array.
array - an array of boolean values, possibly emptytarget - a primitive boolean value
i 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 arrays
public 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
necessary
array, with guaranteed
minimum length minLength
IllegalArgumentException - if minLength or padding is
negative
public 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 objects
collection, in the
same order, converted to primitives
NullPointerException - 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 list
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