@CheckReturnValue @GwtCompatible(emulated=true) public final class Doubles extends Object
Static utility methods pertaining to double primitives, that are not already found in either Double or Arrays.
See the Guava User Guide article on primitive utilities.
| Modifier and Type | Field and Description |
|---|---|
static int |
BYTES
The number of bytes required to represent a primitive
double value. |
| Modifier and Type | Method and Description |
|---|---|
static List<Double> |
asList(double... backingArray)
Returns a fixed-size list backed by the specified array, similar to
Arrays.asList(Object[]). |
static int |
compare(double a,
double b)
Compares the two specified
double values. |
static double[] |
concat(double[]... arrays)
Returns the values from each provided array combined into a single array.
|
static boolean |
contains(double[] array,
double target)
Returns
true if target is present as an element anywhere in array. |
static double[] |
ensureCapacity(double[] 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(double value)
Returns a hash code for
value; 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 value
target in array. |
static int |
indexOf(double[] array,
double[] target)
Returns the start position of the first occurrence of the specified
target within array, or -1 if there is no such occurrence. |
static boolean |
isFinite(double value)
Returns
true if value represents a real number. |
static String |
join(String separator,
double... array)
Returns a string containing the supplied
double values, converted to strings as specified by Double.toString(double), and separated by separator. |
static int |
lastIndexOf(double[] array,
double target)
Returns the index of the last appearance of the value
target in array. |
static Comparator<double[]> |
lexicographicalComparator()
Returns a comparator that compares two
double arrays lexicographically. |
static double |
max(double... array)
Returns the greatest value present in
array, using the same rules of comparison as Math.max(double, double). |
static double |
min(double... array)
Returns the least value present in
array, using the same rules of comparison as Math.min(double, double). |
static Converter<String,Double> |
stringConverter()
Returns a serializable converter object that converts between strings and doubles using
Double.valueOf(java.lang.String) and Double.toString(). |
static double[] |
toArray(Collection<? extends Number> collection)
Returns an array containing each value of
collection, converted to a double value in the manner of Number.doubleValue(). |
static Double |
tryParse(String string)
Parses the specified string as a double-precision floating point value.
|
public static final int BYTES
The number of bytes required to represent a primitive double value.
public static int hashCode(double value)
Returns a hash code for value; equal to the result of invoking ((Double) value).hashCode().
value - a primitive double valuepublic static int compare(double a,
double b)
Compares the two specified double 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, and 0.0 > -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.
a - the first double to compareb - the second double to comparea is less than b; a positive value if a is greater than b; or zero if they are equalpublic static boolean isFinite(double value)
Returns true if value represents a real number. This is equivalent to, but not necessarily implemented as, !(Double.isInfinite(value) || Double.isNaN(value)).
public static boolean contains(double[] array,
double target)
Returns true if target is present as an element anywhere in array. Note that this always returns false when target is NaN.
array - an array of double values, possibly emptytarget - a primitive double valuetrue if array[i] == target for some value of ipublic static int indexOf(double[] array,
double target)
Returns the index of the first appearance of the value target in array. Note that this always returns -1 when target is NaN.
array - an array of double values, possibly emptytarget - a primitive double valuei for which array[i] == target, or -1 if no such index exists.public static int indexOf(double[] array,
double[] 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 java.util.Arrays.copyOfRange(array, i, i + target.length) contains exactly the same elements as target.
Note that this always returns -1 when target contains NaN.
array - the array to search for the sequence targettarget - the array to search for as a sub-sequence of arraypublic static int lastIndexOf(double[] array,
double target)
Returns the index of the last appearance of the value target in array. Note that this always returns -1 when target is NaN.
array - an array of double values, possibly emptytarget - a primitive double valuei for which array[i] == target, or -1 if no such index exists.public static double min(double... array)
Returns the least value present in array, using the same rules of comparison as Math.min(double, double).
array - a nonempty array of double valuesarray that is less than or equal to every other value in the arrayIllegalArgumentException - if array is emptypublic static double max(double... array)
Returns the greatest value present in array, using the same rules of comparison as Math.max(double, double).
array - a nonempty array of double valuesarray that is greater than or equal to every other value in the arrayIllegalArgumentException - if array is emptypublic 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}.
arrays - zero or more double arrays@Beta public static Converter<String,Double> stringConverter()
Returns a serializable converter object that converts between strings and doubles using Double.valueOf(java.lang.String) and Double.toString().
public static double[] ensureCapacity(double[] 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.
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 minLengthIllegalArgumentException - if minLength or padding is negativepublic static String join(String separator, double... array)
Returns a string containing the supplied double values, converted to strings as specified by Double.toString(double), and separated by separator. For example, join("-", 1.0, 2.0, 3.0) returns the string "1.0-2.0-3.0".
Note that Double.toString(double) formats double differently in GWT sometimes. In the previous example, it returns the string "1-2-3".
separator - the text that should appear between consecutive values in the resulting string (but not at the start or end)array - an array of double values, possibly emptypublic static Comparator<double[]> lexicographicalComparator()
Returns a comparator that compares two double arrays lexicographically. That is, it compares, using compare(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 with Arrays.equals(double[], double[]).
public static double[] toArray(Collection<? extends Number> collection)
Returns an array containing each value of collection, converted to a double value in the manner of Number.doubleValue().
Elements are copied from the argument collection as if by collection.toArray(). Calling this method is as thread-safe as calling that method.
collection - a collection of Number instancescollection, in the same order, converted to primitivesNullPointerException - if collection or any of its elements is nullCollection<Double> before 12.0)public static List<Double> asList(double... 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 Double objects written to or read from it. For example, whether list.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 if NaN is used as a parameter to any of its methods.
backingArray - the array to back the list@Beta @Nullable @CheckForNull @GwtIncompatible(value="regular expressions") public static Double tryParse(String string)
Parses the specified string as a double-precision floating point value. The ASCII character '-' (‘\u002D’) is recognized as the minus sign.
Unlike Double.parseDouble(String), this method returns null instead of throwing an exception if parsing fails. Valid inputs are exactly those accepted by Double.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.
string - the string representation of a double valuestring, or null if string has a length of zero or cannot be parsed as a double value