com.google.common.primitives
Class Floats

java.lang.Object
  extended by com.google.common.primitives.Floats

public final class Floats
extends Object

Static utility methods pertaining to float primitives, that are not already found in either Float or Arrays.

Since:
2009.09.15 tentative
Author:
Kevin Bourrillion

Method Summary
static List<Float> asList(float... backingArray)
          Returns a fixed-size list backed by the specified array, similar to Arrays.asList(Object[]).
static int compare(float a, float b)
          Compares the two specified float values using Float.compare(float, float).
static float[] concat(float[]... arrays)
          Returns the values from each provided array combined into a single array.
static boolean contains(float[] array, float target)
          Returns true if target is present as an element anywhere in array.
static float[] ensureCapacity(float[] 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(float value)
          Returns a hash code for value; equal to the result of invoking ((Float) value).hashCode().
static int indexOf(float[] array, float target)
          Returns the index of the first appearance of the value target in array.
static int indexOf(float[] array, float[] 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, float... array)
          Returns a string containing the supplied float values, converted to strings as specified by Float.toString(float), and separated by separator.
static int lastIndexOf(float[] array, float target)
          Returns the index of the last appearance of the value target in array.
static Comparator<float[]> lexicographicalComparator()
          Returns a comparator that compares two float arrays lexicographically.
static float max(float... array)
          Returns the greatest value present in array, using the same rules of comparison as Math.min(float, float).
static float min(float... array)
          Returns the least value present in array, using the same rules of comparison as Math.min(float, float).
static float[] toArray(Collection<Float> collection)
          Copies a collection of Float instances into a new array of primitive float values.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

hashCode

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

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

compare

public static int compare(float a,
                          float b)
Compares the two specified float values using Float.compare(float, float). You may prefer to invoke that method directly; this method exists only for consistency with the other utilities in this package.

Parameters:
a - the first float to compare
b - the second float to compare
Returns:
the result of invoking Float.compare(float, float)

contains

public static boolean contains(float[] array,
                               float 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 float values, possibly empty
target - a primitive float value
Returns:
true if array[i] == target for some value of i

indexOf

public static int indexOf(float[] array,
                          float 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 float values, possibly empty
target - a primitive float value
Returns:
the least index i for which array[i] == target, or -1 if no such index exists.

indexOf

public static int indexOf(float[] array,
                          float[] 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.

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

min

public static float min(float... array)
Returns the least value present in array, using the same rules of comparison as Math.min(float, float).

Parameters:
array - a nonempty array of float 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 float max(float... array)
Returns the greatest value present in array, using the same rules of comparison as Math.min(float, float).

Parameters:
array - a nonempty array of float 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

concat

public static float[] concat(float[]... arrays)
Returns the values from each provided array combined into a single array. For example, concat(new float[] {a, b}, new float[] {}, new float[] {c} returns the array {a, b, c}.

Parameters:
arrays - zero or more float arrays
Returns:
a single array containing all the values from the source arrays, in order

ensureCapacity

public static float[] ensureCapacity(float[] 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,
                          float... array)
Returns a string containing the supplied float values, converted to strings as specified by Float.toString(float), and separated by separator. For example, join("-", 1.0f, 2.0f, 3.0f) returns the string "1.0-2.0-3.0".

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 float values, possibly empty

lexicographicalComparator

public static Comparator<float[]> lexicographicalComparator()
Returns a comparator that compares two float arrays lexicographically. That is, it compares, using compare(float, float)), 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, [] < [1.0f] < [1.0f, 2.0f] < [2.0f].

The returned comparator is inconsistent with Object.equals(Object) (since arrays support only identity equality), but it is consistent with Arrays.equals(float[], float[]).

Since:
2010.01.04 tentative
See Also:
Lexicographical order article at Wikipedia

toArray

public static float[] toArray(Collection<Float> collection)
Copies a collection of Float instances into a new array of primitive float values.

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 Float 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<Float> asList(float... 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 Float 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.

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