Class Doubles
 java.lang.Object

 com.google.common.primitives.Doubles

@GwtCompatible(emulated=true) public final class Doubles extends Object
Static utility methods pertaining todouble
primitives, that are not already found in eitherDouble
orArrays
.See the Guava User Guide article on primitive utilities.
 Since:
 1.0
 Author:
 Kevin Bourrillion


Field Summary
Fields Modifier and Type Field Description static int
BYTES
The number of bytes required to represent a primitivedouble
value.

Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static List<Double>
asList(double... backingArray)
Returns a fixedsize list backed by the specified array, similar toArrays.asList(Object[])
.static int
compare(double a, double b)
Compares the two specifieddouble
values.static double[]
concat(double[]... arrays)
Returns the values from each provided array combined into a single array.static double
constrainToRange(double value, double min, double max)
Returns the value nearest tovalue
which is within the closed range[min..max]
.static boolean
contains(double[] array, double target)
Returnstrue
iftarget
is present as an element anywhere inarray
.static double[]
ensureCapacity(double[] array, int minLength, int padding)
Returns an array containing the same values asarray
, but guaranteed to be of a specified minimum length.static int
hashCode(double value)
Returns a hash code forvalue
; equal to the result of invoking((Double) value).hashCode()
.static int
indexOf(double[] array, double target)
Returns the index of the first appearance of the valuetarget
inarray
.static int
indexOf(double[] array, double[] target)
Returns the start position of the first occurrence of the specifiedtarget
withinarray
, or1
if there is no such occurrence.static boolean
isFinite(double value)
Returnstrue
ifvalue
represents a real number.static String
join(String separator, double... array)
Returns a string containing the supplieddouble
values, converted to strings as specified byDouble.toString(double)
, and separated byseparator
.static int
lastIndexOf(double[] array, double target)
Returns the index of the last appearance of the valuetarget
inarray
.static Comparator<double[]>
lexicographicalComparator()
Returns a comparator that compares twodouble
arrays lexicographically.static double
max(double... array)
Returns the greatest value present inarray
, using the same rules of comparison asMath.max(double, double)
.static double
min(double... array)
Returns the least value present inarray
, using the same rules of comparison asMath.min(double, double)
.static void
reverse(double[] array)
Reverses the elements ofarray
.static void
reverse(double[] array, int fromIndex, int toIndex)
Reverses the elements ofarray
betweenfromIndex
inclusive andtoIndex
exclusive.static void
sortDescending(double[] array)
Sorts the elements ofarray
in descending order.static void
sortDescending(double[] array, int fromIndex, int toIndex)
Sorts the elements ofarray
betweenfromIndex
inclusive andtoIndex
exclusive in descending order.static Converter<String,Double>
stringConverter()
Returns a serializable converter object that converts between strings and doubles usingDouble.valueOf(java.lang.String)
andDouble.toString()
.static double[]
toArray(Collection<? extends Number> collection)
Returns an array containing each value ofcollection
, converted to adouble
value in the manner ofNumber.doubleValue()
.static @Nullable Double
tryParse(String string)
Parses the specified string as a doubleprecision floating point value.



Field Detail

BYTES
public static final int BYTES
The number of bytes required to represent a primitivedouble
value.Java 8 users: use
Double.BYTES
instead. Since:
 10.0
 See Also:
 Constant Field Values


Method Detail

hashCode
public static int hashCode(double value)
Returns a hash code forvalue
; equal to the result of invoking((Double) value).hashCode()
.Java 8 users: use
Double.hashCode(double)
instead. Parameters:
value
 a primitivedouble
value Returns:
 a hash code for the value

compare
public static int compare(double a, double b)
Compares the two specifieddouble
values. The sign of the value returned is the same as that of((Double) a).compareTo(b)
. As with that method,NaN
is treated as greater than all other values, and0.0 > 0.0
.Note: this method simply delegates to the JDK method
Double.compare(double, double)
. It is provided for consistency with the other primitive types, whose compare methods were not added to the JDK until JDK 7. Parameters:
a
 the firstdouble
to compareb
 the seconddouble
to compare Returns:
 a negative value if
a
is less thanb
; a positive value ifa
is greater thanb
; or zero if they are equal

isFinite
public static boolean isFinite(double value)
Returnstrue
ifvalue
represents a real number. This is equivalent to, but not necessarily implemented as,!(Double.isInfinite(value)  Double.isNaN(value))
.Java 8 users: use
Double.isFinite(double)
instead. Since:
 10.0

contains
public static boolean contains(double[] array, double target)
Returnstrue
iftarget
is present as an element anywhere inarray
. Note that this always returnsfalse
whentarget
isNaN
. Parameters:
array
 an array ofdouble
values, possibly emptytarget
 a primitivedouble
value Returns:
true
ifarray[i] == target
for some value ofi

indexOf
public static int indexOf(double[] array, double target)
Returns the index of the first appearance of the valuetarget
inarray
. Note that this always returns1
whentarget
isNaN
. Parameters:
array
 an array ofdouble
values, possibly emptytarget
 a primitivedouble
value Returns:
 the least index
i
for whicharray[i] == target
, or1
if no such index exists.

indexOf
public static int indexOf(double[] array, double[] target)
Returns the start position of the first occurrence of the specifiedtarget
withinarray
, or1
if there is no such occurrence.More formally, returns the lowest index
i
such thatArrays.copyOfRange(array, i, i + target.length)
contains exactly the same elements astarget
.Note that this always returns
1
whentarget
containsNaN
. Parameters:
array
 the array to search for the sequencetarget
target
 the array to search for as a subsequence ofarray

lastIndexOf
public static int lastIndexOf(double[] array, double target)
Returns the index of the last appearance of the valuetarget
inarray
. Note that this always returns1
whentarget
isNaN
. Parameters:
array
 an array ofdouble
values, possibly emptytarget
 a primitivedouble
value Returns:
 the greatest index
i
for whicharray[i] == target
, or1
if no such index exists.

min
@GwtIncompatible("Available in GWT! Annotation is to avoid conflict with GWT specialization of base class.") public static double min(double... array)
Returns the least value present inarray
, using the same rules of comparison asMath.min(double, double)
. Parameters:
array
 a nonempty array ofdouble
values Returns:
 the value present in
array
that is less than or equal to every other value in the array  Throws:
IllegalArgumentException
 ifarray
is empty

max
@GwtIncompatible("Available in GWT! Annotation is to avoid conflict with GWT specialization of base class.") public static double max(double... array)
Returns the greatest value present inarray
, using the same rules of comparison asMath.max(double, double)
. Parameters:
array
 a nonempty array ofdouble
values Returns:
 the value present in
array
that is greater than or equal to every other value in the array  Throws:
IllegalArgumentException
 ifarray
is empty

constrainToRange
@Beta public static double constrainToRange(double value, double min, double max)
Returns the value nearest tovalue
which is within the closed range[min..max]
.If
value
is within the range[min..max]
,value
is returned unchanged. Ifvalue
is less thanmin
,min
is returned, and ifvalue
is greater thanmax
,max
is returned. Parameters:
value
 thedouble
value to constrainmin
 the lower bound (inclusive) of the range to constrainvalue
tomax
 the upper bound (inclusive) of the range to constrainvalue
to Throws:
IllegalArgumentException
 ifmin > max
 Since:
 21.0

concat
public static double[] concat(double[]... arrays)
Returns the values from each provided array combined into a single array. For example,concat(new double[] {a, b}, new double[] {}, new double[] {c}
returns the array{a, b, c}
. Parameters:
arrays
 zero or moredouble
arrays Returns:
 a single array containing all the values from the source arrays, in order

stringConverter
@Beta public static Converter<String,Double> stringConverter()
Returns a serializable converter object that converts between strings and doubles usingDouble.valueOf(java.lang.String)
andDouble.toString()
. Since:
 16.0

ensureCapacity
public static double[] ensureCapacity(double[] array, int minLength, int padding)
Returns an array containing the same values asarray
, but guaranteed to be of a specified minimum length. Ifarray
already has a length of at leastminLength
, it is returned directly. Otherwise, a new array of sizeminLength + padding
is returned, containing the values ofarray
, and zeroes in the remaining places. Parameters:
array
 the source arrayminLength
 the minimum length the returned array must guaranteepadding
 an extra amount to "grow" the array by if growth is necessary Returns:
 an array containing the values of
array
, with guaranteed minimum lengthminLength
 Throws:
IllegalArgumentException
 ifminLength
orpadding
is negative

join
public static String join(String separator, double... array)
Returns a string containing the supplieddouble
values, converted to strings as specified byDouble.toString(double)
, and separated byseparator
. For example,join("", 1.0, 2.0, 3.0)
returns the string"1.02.03.0"
.Note that
Double.toString(double)
formatsdouble
differently in GWT sometimes. In the previous example, it returns the string"123"
. Parameters:
separator
 the text that should appear between consecutive values in the resulting string (but not at the start or end)array
 an array ofdouble
values, possibly empty

lexicographicalComparator
public static Comparator<double[]> lexicographicalComparator()
Returns a comparator that compares twodouble
arrays lexicographically. That is, it compares, usingcompare(double, double)
), 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,[] < [1.0] < [1.0, 2.0] < [2.0]
.The returned comparator is inconsistent with
Object.equals(Object)
(since arrays support only identity equality), but it is consistent withArrays.equals(double[], double[])
. Since:
 2.0

sortDescending
public static void sortDescending(double[] array)
Sorts the elements ofarray
in descending order.Note that this method uses the total order imposed by
Double.compare(double, double)
, which treats all NaN values as equal and 0.0 as greater than 0.0. Since:
 23.1

sortDescending
public static void sortDescending(double[] array, int fromIndex, int toIndex)
Sorts the elements ofarray
betweenfromIndex
inclusive andtoIndex
exclusive in descending order.Note that this method uses the total order imposed by
Double.compare(double, double)
, which treats all NaN values as equal and 0.0 as greater than 0.0. Since:
 23.1

reverse
public static void reverse(double[] array)
Reverses the elements ofarray
. This is equivalent toCollections.reverse(Doubles.asList(array))
, but is likely to be more efficient. Since:
 23.1

reverse
public static void reverse(double[] array, int fromIndex, int toIndex)
Reverses the elements ofarray
betweenfromIndex
inclusive andtoIndex
exclusive. This is equivalent toCollections.reverse(Doubles.asList(array).subList(fromIndex, toIndex))
, but is likely to be more efficient. Throws:
IndexOutOfBoundsException
 iffromIndex < 0
,toIndex > array.length
, ortoIndex > fromIndex
 Since:
 23.1

toArray
public static double[] toArray(Collection<? extends Number> collection)
Returns an array containing each value ofcollection
, converted to adouble
value in the manner ofNumber.doubleValue()
.Elements are copied from the argument collection as if by
collection.toArray()
. Calling this method is as threadsafe as calling that method. Parameters:
collection
 a collection ofNumber
instances Returns:
 an array containing the same values as
collection
, in the same order, converted to primitives  Throws:
NullPointerException
 ifcollection
or any of its elements is null Since:
 1.0 (parameter was
Collection<Double>
before 12.0)

asList
public static List<Double> asList(double... backingArray)
Returns a fixedsize list backed by the specified array, similar toArrays.asList(Object[])
. The list supportsList.set(int, Object)
, but any attempt to set a value tonull
will result in aNullPointerException
.The returned list maintains the values, but not the identities, of
Double
objects written to or read from it. For example, whetherlist.get(0) == list.get(0)
is true for the returned list is unspecified.The returned list may have unexpected behavior if it contains
NaN
, or ifNaN
is used as a parameter to any of its methods.Note: when possible, you should represent your data as an
ImmutableDoubleArray
instead, which has anasList
view. Parameters:
backingArray
 the array to back the list Returns:
 a list view of the array

tryParse
@Beta @GwtIncompatible public static @Nullable Double tryParse(String string)
Parses the specified string as a doubleprecision floating point value. The ASCII character''
('\u002D'
) is recognized as the minus sign.Unlike
Double.parseDouble(String)
, this method returnsnull
instead of throwing an exception if parsing fails. Valid inputs are exactly those accepted byDouble.valueOf(String)
, except that leading and trailing whitespace is not permitted.This implementation is likely to be faster than
Double.parseDouble
if many failures are expected. Parameters:
string
 the string representation of adouble
value Returns:
 the floating point value represented by
string
, ornull
ifstring
has a length of zero or cannot be parsed as adouble
value  Throws:
NullPointerException
 ifstring
isnull
 Since:
 14.0

