Module dev.mccue.guava.primitives
Package dev.mccue.guava.primitives

Class Doubles

java.lang.Object
dev.mccue.guava.primitives.Doubles
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.

Since:
1.0
Author:
Kevin Bourrillion

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    BYTES
    The number of bytes required to represent a primitive double value.

  • Method Summary

    Modifier and Type
    Method
    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 double
    constrainToRange(double value, double min, double max)
    Returns the value nearest to value which is within the closed range [min..max].
    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 void
    reverse(double[] array)
    Reverses the elements of array.
    static void
    reverse(double[] array, int fromIndex, int toIndex)
    Reverses the elements of array between fromIndex inclusive and toIndex exclusive.
    static void
    rotate(double[] array, int distance)
    Performs a right rotation of array of "distance" places, so that the first element is moved to index "distance", and the element at index i ends up at index (distance + i) mod array.length.
    static void
    rotate(double[] array, int distance, int fromIndex, int toIndex)
    Performs a right rotation of array between fromIndex inclusive and toIndex exclusive.
    static void
    sortDescending(double[] array)
    Sorts the elements of array in descending order.
    static void
    sortDescending(double[] array, int fromIndex, int toIndex)
    Sorts the elements of array between fromIndex inclusive and toIndex exclusive in descending order.
    static dev.mccue.guava.base.Converter<String,Double>
    stringConverter()
    Returns a serializable converter object that converts between strings and doubles using Double#valueOf 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.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • BYTES

      public static final int BYTES
      The number of bytes required to represent a primitive double value.

      Java 8+ users: use Double#BYTES instead.

      Since:
      10.0
      See Also:

  • Method Details

    • hashCode

      public static int hashCode(double value)
      Returns a hash code for value; equal to the result of invoking ((Double) value).hashCode().

      Java 8+ users: use Double#hashCode(double) instead.

      Parameters:
      value - a primitive double value
      Returns:
      a hash code for the value

    • compare

      public 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).Double#compareTo 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. 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 first double to compare
      b - the second double to compare
      Returns:
      a negative value if a is less than b; a positive value if a is greater than b; or zero if they are equal

    • isFinite

      public 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)).

      Java 8+ users: use Double#isFinite(double) instead.

      Since:
      10.0

    • contains

      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.
      Parameters:
      array - an array of double values, possibly empty
      target - a primitive double value
      Returns:
      true if array[i] == target for some value of i

    • indexOf

      public 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.
      Parameters:
      array - an array of double values, possibly empty
      target - a primitive double value
      Returns:
      the least index i for which array[i] == target, or -1 if no such index exists.

    • indexOf

      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 Arrays.copyOfRange(array, i, i + target.length) contains exactly the same elements as target.

      Note that this always returns -1 when target contains NaN.

      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(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.
      Parameters:
      array - an array of double values, possibly empty
      target - a primitive double value
      Returns:
      the greatest index i for which array[i] == target, or -1 if no such index exists.

    • min

      public static double min(double... array)
      Returns the least value present in array, using the same rules of comparison as Math#min(double, double).
      Parameters:
      array - a nonempty array of double values
      Returns:
      the value present in array that is less than or equal to every other value in the array
      Throws:
      IllegalArgumentException - if array is empty

    • max

      public static double max(double... array)
      Returns the greatest value present in array, using the same rules of comparison as Math#max(double, double).
      Parameters:
      array - a nonempty array of double values
      Returns:
      the value present in array that is greater than or equal to every other value in the array
      Throws:
      IllegalArgumentException - if array is empty

    • constrainToRange

      public static double constrainToRange(double value, double min, double max)
      Returns the value nearest to value which is within the closed range [min..max].

      If value is within the range [min..max], value is returned unchanged. If value is less than min, min is returned, and if value is greater than max, max is returned.

      Parameters:
      value - the double value to constrain
      min - the lower bound (inclusive) of the range to constrain value to
      max - the upper bound (inclusive) of the range to constrain value to
      Throws:
      IllegalArgumentException - if min > 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 more double arrays
      Returns:
      a single array containing all the values from the source arrays, in order

    • stringConverter

      public static dev.mccue.guava.base.Converter<String,Double> stringConverter()
      Returns a serializable converter object that converts between strings and doubles using Double#valueOf and Double#toString().
      Since:
      16.0

    • ensureCapacity

      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.
      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, 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".

      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 double values, possibly empty

    • lexicographicalComparator

      public 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[]).

      Since:
      2.0

    • sortDescending

      public static void sortDescending(double[] array)
      Sorts the elements of array in descending order.

      Note that this method uses the total order imposed by Double#compare, 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 of array between fromIndex inclusive and toIndex exclusive in descending order.

      Note that this method uses the total order imposed by Double#compare, 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 of array. This is equivalent to Collections.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 of array between fromIndex inclusive and toIndex exclusive. This is equivalent to Collections.reverse(Doubles.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

    • rotate

      public static void rotate(double[] array, int distance)
      Performs a right rotation of array of "distance" places, so that the first element is moved to index "distance", and the element at index i ends up at index (distance + i) mod array.length. This is equivalent to Collections.rotate(Bytes.asList(array), distance), but is considerably faster and avoids allocation and garbage collection.

      The provided "distance" may be negative, which will rotate left.

      Since:
      32.0.0

    • rotate

      public static void rotate(double[] array, int distance, int fromIndex, int toIndex)
      Performs a right rotation of array between fromIndex inclusive and toIndex exclusive. This is equivalent to Collections.rotate(Bytes.asList(array).subList(fromIndex, toIndex), distance), but is considerably faster and avoids allocations and garbage collection.

      The provided "distance" may be negative, which will rotate left.

      Throws:
      IndexOutOfBoundsException - if fromIndex < 0, toIndex > array.length, or toIndex > fromIndex
      Since:
      32.0.0

    • toArray

      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.

      Parameters:
      collection - a collection of Number instances
      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
      Since:
      1.0 (parameter was Collection<Double> before 12.0)

    • asList

      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.

      The returned list is serializable.

      Note: when possible, you should represent your data as an ImmutableDoubleArray instead, which has an ImmutableDoubleArray#asList asList view.

      Parameters:
      backingArray - the array to back the list
      Returns:
      a list view of the array

    • tryParse

      @CheckForNull 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.

      Parameters:
      string - the string representation of a double value
      Returns:
      the floating point value represented by string, or null if string has a length of zero or cannot be parsed as a double value
      Throws:
      NullPointerException - if string is null
      Since:
      14.0