Booleans (Guava: Google Core Libraries for Java 29.0-jre API)

java.lang.Object
- com.google.common.primitives.Booleans

```
@GwtCompatible
public final class Booleans
extends Object
```
Static utility methods pertaining to boolean primitives, that are not already found in either Boolean or Arrays.
See the Guava User Guide article on primitive utilities.

Since:

1.0

Author:

Kevin Bourrillion

Method Summary

All Methods Static Methods Concrete Methods
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 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(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`.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - trueFirst
```
@Beta
public static Comparator<Boolean> trueFirst()
```
    Returns a 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()).
    
    Since:
    
    21.0
  - falseFirst
```
@Beta
public static Comparator<Boolean> falseFirst()
```
    Returns a 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()).
    
    Since:
    
    21.0
  - hashCode
```
public static int hashCode(boolean value)
```
    Returns a hash code for value; equal to the result of invoking ((Boolean) value).hashCode().
    Java 8 users: use Boolean.hashCode(boolean) instead.
    
    Parameters:
    
    value - a primitive boolean value
    
    Returns:
    
    a hash code for the value
  - compare
```
public static int compare(boolean a,
                          boolean b)
```
    Compares the two specified 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.
    
    Parameters:
    
    a - the first boolean to compare
    
    b - the second boolean to compare
    
    Returns:
    
    a positive number if only a is true, a negative number if only b is true, or zero if a == b
  - contains
```
public static boolean contains(boolean[] array,
                               boolean target)
```
    Returns 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.
    
    Parameters:
    
    array - an array of boolean values, possibly empty
    
    target - a primitive boolean value
    
    Returns:
    
    true if array[i] == target for some value of i
  - indexOf
```
public static int indexOf(boolean[] array,
                          boolean target)
```
    Returns the index of the first appearance of the value target in array.
    Note: consider representing the array as a BitSet instead, and using BitSet.nextSetBit(int) or BitSet.nextClearBit(int).
    
    Parameters:
    
    array - an array of boolean values, possibly empty
    
    target - a primitive boolean value
    
    Returns:
    
    the least index i for which array[i] == target, or -1 if no such index exists.
  - indexOf
```
public 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.
    More formally, returns the lowest index i such that Arrays.copyOfRange(array, i, i + target.length) contains exactly the same elements as target.
    
    Parameters:
    
    array - the array to search for the sequence target
    
    target - the array to search for as a sub-sequence of array
  - lastIndexOf
```
public static int lastIndexOf(boolean[] array,
                              boolean target)
```
    Returns the index of the last appearance of the value target in array.
    
    Parameters:
    
    array - an array of boolean values, possibly empty
    
    target - a primitive boolean value
    
    Returns:
    
    the greatest index i for which array[i] == target, or -1 if no such index exists.
  - concat
```
public static boolean[] concat(boolean[]... arrays)
```
    Returns the values from each provided array combined into a single array. For example, concat(new boolean[] {a, b}, new boolean[] {}, new boolean[] {c} returns the array {a, b, c}.
    
    Parameters:
    
    arrays - zero or more boolean arrays
    
    Returns:
    
    a single array containing all the values from the source arrays, in order
  - ensureCapacity
```
public 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. 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.
    
    Parameters:
    
    array - the source array
    
    minLength - the minimum length the returned array must guarantee
    
    padding - an extra amount to "grow" the array by if growth is necessary
    
    Returns:
    
    an array containing the values of array, with guaranteed minimum length minLength
    
    Throws:
    
    IllegalArgumentException - if minLength or padding is negative
  - join
```
public static String join(String separator,
                          boolean... array)
```
    Returns a string containing the supplied boolean values separated by separator. For example, join("-", false, true, false) returns the string "false-true-false".
    
    Parameters:
    
    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 empty
  - lexicographicalComparator
```
public static Comparator<boolean[]> lexicographicalComparator()
```
    Returns a comparator that compares two 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[]).
    
    Since:
    
    2.0
  - toArray
```
public static boolean[] toArray(Collection<Boolean> collection)
```
    Copies a collection of 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.
    
    Parameters:
    
    collection - a collection of Boolean objects
    
    Returns:
    
    an array containing the same values as collection, in the same order, converted to primitives
    
    Throws:
    
    NullPointerException - if collection or any of its elements is null
  - asList
```
public static List<Boolean> asList(boolean... backingArray)
```
    Returns a fixed-size list backed by the specified array, similar to 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.
    
    Parameters:
    
    backingArray - the array to back the list
    
    Returns:
    
    a list view of the array
  - countTrue
```
@Beta
public static int countTrue(boolean... values)
```
    Returns the number of values that are true.
    
    Since:
    
    16.0
  - reverse
```
public static void reverse(boolean[] array)
```
    Reverses the elements of array. This is equivalent to Collections.reverse(Booleans.asList(array)), but is likely to be more efficient.
    
    Since:
    
    23.1
  - reverse
```
public static void reverse(boolean[] array,
                           int fromIndex,
                           int toIndex)
```
    Reverses the elements of 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.
    
    Throws:
    
    IndexOutOfBoundsException - if fromIndex < 0, toIndex > array.length, or toIndex > fromIndex
    
    Since:
    
    23.1

Class Booleans

Method Summary

Methods inherited from class java.lang.Object

Method Detail

trueFirst

falseFirst

hashCode

compare

contains

indexOf

indexOf

lastIndexOf

concat

ensureCapacity

join

lexicographicalComparator

toArray

asList

countTrue

reverse

reverse