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com.google.common.primitives
Class Ints

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

@GwtCompatible(emulated=true)
public final class Ints
extends Object

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

Since:
1
Author:
Kevin Bourrillion

Field Summary
static int BYTES
          The number of bytes required to represent a primitive int value.
 
Method Summary
static List<Integer> asList(int... backingArray)
          Returns a fixed-size list backed by the specified array, similar to Arrays.asList(Object[]).
static int checkedCast(long value)
          Returns the int value that is equal to value, if possible.
static int compare(int a, int b)
          Compares the two specified int values.
static int[] concat(int[]... arrays)
          Returns the values from each provided array combined into a single array.
static boolean contains(int[] array, int target)
          Returns true if target is present as an element anywhere in array.
static int[] ensureCapacity(int[] 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 fromByteArray(byte[] bytes)
          Returns the int value whose big-endian representation is stored in the first 4 bytes of bytes; equivalent to ByteBuffer.wrap(bytes).getInt().
static int fromBytes(byte b1, byte b2, byte b3, byte b4)
          Returns the int value whose byte representation is the given 4 bytes, in big-endian order; equivalent to Ints.fromByteArray(new byte[] {b1, b2, b3, b4}).
static int hashCode(int value)
          Returns a hash code for value; equal to the result of invoking ((Integer) value).hashCode().
static int indexOf(int[] array, int target)
          Returns the index of the first appearance of the value target in array.
static int indexOf(int[] array, int[] 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, int... array)
          Returns a string containing the supplied int values separated by separator.
static int lastIndexOf(int[] array, int target)
          Returns the index of the last appearance of the value target in array.
static Comparator<int[]> lexicographicalComparator()
          Returns a comparator that compares two int arrays lexicographically.
static int max(int... array)
          Returns the greatest value present in array.
static int min(int... array)
          Returns the least value present in array.
static int saturatedCast(long value)
          Returns the int nearest in value to value.
static int[] toArray(Collection<Integer> collection)
          Copies a collection of Integer instances into a new array of primitive int values.
static byte[] toByteArray(int value)
          Returns a big-endian representation of value in a 4-element byte array; equivalent to ByteBuffer.allocate(4).putInt(value).array().
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

BYTES

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

See Also:
Constant Field Values
Method Detail

hashCode

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

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

checkedCast

public static int checkedCast(long value)
Returns the int value that is equal to value, if possible.

Parameters:
value - any value in the range of the int type
Returns:
the int value that equals value
Throws:
IllegalArgumentException - if value is greater than Integer.MAX_VALUE or less than Integer.MIN_VALUE

saturatedCast

public static int saturatedCast(long value)
Returns the int nearest in value to value.

Parameters:
value - any long value
Returns:
the same value cast to int if it is in the range of the int type, Integer.MAX_VALUE if it is too large, or Integer.MIN_VALUE if it is too small

compare

public static int compare(int a,
                          int b)
Compares the two specified int values. The sign of the value returned is the same as that of ((Integer) a).compareTo(b).

Parameters:
a - the first int to compare
b - the second int 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

contains

public static boolean contains(int[] array,
                               int target)
Returns true if target is present as an element anywhere in array.

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

indexOf

public static int indexOf(int[] array,
                          int target)
Returns the index of the first appearance of the value target in array.

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

indexOf

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

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(int[] array,
                              int target)
Returns the index of the last appearance of the value target in array.

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

min

public static int min(int... array)
Returns the least value present in array.

Parameters:
array - a nonempty array of int 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 int max(int... array)
Returns the greatest value present in array.

Parameters:
array - a nonempty array of int 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 int[] concat(int[]... arrays)
Returns the values from each provided array combined into a single array. For example, concat(new int[] {a, b}, new int[] {}, new int[] {c} returns the array {a, b, c}.

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

toByteArray

@GwtIncompatible(value="doesn\'t work")
public static byte[] toByteArray(int value)
Returns a big-endian representation of value in a 4-element byte array; equivalent to ByteBuffer.allocate(4).putInt(value).array(). For example, the input value 0x12131415 would yield the byte array {0x12, 0x13, 0x14, 0x15}.

If you need to convert and concatenate several values (possibly even of different types), use a shared ByteBuffer instance, or use ByteStreams.newDataOutput() to get a growable buffer.

fromByteArray

@GwtIncompatible(value="doesn\'t work")
public static int fromByteArray(byte[] bytes)
Returns the int value whose big-endian representation is stored in the first 4 bytes of bytes; equivalent to ByteBuffer.wrap(bytes).getInt(). For example, the input byte array {0x12, 0x13, 0x14, 0x15, 0x33} would yield the int value 0x12131415.

Arguably, it's preferable to use ByteBuffer; that library exposes much more flexibility at little cost in readability.

Throws:
IllegalArgumentException - if bytes has fewer than 4 elements

fromBytes

@GwtIncompatible(value="doesn\'t work")
public static int fromBytes(byte b1,
                                                 byte b2,
                                                 byte b3,
                                                 byte b4)
Returns the int value whose byte representation is the given 4 bytes, in big-endian order; equivalent to Ints.fromByteArray(new byte[] {b1, b2, b3, b4}).

Since:
7

ensureCapacity

public static int[] ensureCapacity(int[] 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,
                          int... array)
Returns a string containing the supplied int values separated by separator. For example, join("-", 1, 2, 3) 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 int values, possibly empty

lexicographicalComparator

public static Comparator<int[]> lexicographicalComparator()
Returns a comparator that compares two int arrays lexicographically. That is, it compares, using compare(int, int)), 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] < [1, 2] < [2].

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

Since:
2
See Also:
Lexicographical order article at Wikipedia

toArray

public static int[] toArray(Collection<Integer> collection)
Copies a collection of Integer instances into a new array of primitive int 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 Integer 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<Integer> asList(int... 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 Integer 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
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