@CheckReturnValue @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.
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
int value. |
static int |
MAX_POWER_OF_TWO
The largest power of two that can be represented as an
int. |
| Modifier and Type | Method and Description |
|---|---|
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 Converter<String,Integer> |
stringConverter()
Returns a serializable converter object that converts between strings and integers using
Integer.decode(java.lang.String) and Integer.toString(). |
static int[] |
toArray(Collection<? extends Number> collection)
Returns an array containing each value of
collection, converted to a int value in the manner of Number.intValue(). |
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(). |
static Integer |
tryParse(String string)
Parses the specified string as a signed decimal integer value.
|
static Integer |
tryParse(String string,
int radix)
Parses the specified string as a signed integer value using the specified radix.
|
public static final int BYTES
The number of bytes required to represent a primitive int value.
public static final int MAX_POWER_OF_TWO
The largest power of two that can be represented as an int.
public static int hashCode(int value)
Returns a hash code for value; equal to the result of invoking ((Integer) value).hashCode().
value - a primitive int valuepublic static int checkedCast(long value)
Returns the int value that is equal to value, if possible.
value - any value in the range of the int typeint value that equals valueIllegalArgumentException - if value is greater than Integer.MAX_VALUE or less than Integer.MIN_VALUEpublic static int saturatedCast(long value)
Returns the int nearest in value to value.
value - any long valueint 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 smallpublic 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).
Note for Java 7 and later: this method should be treated as deprecated; use the equivalent Integer.compare(int, int) method instead.
a - the first int to compareb - the second int to comparea is less than b; a positive value if a is greater than b; or zero if they are equalpublic static boolean contains(int[] array,
int target)
Returns true if target is present as an element anywhere in array.
array - an array of int values, possibly emptytarget - a primitive int valuetrue if array[i] == target for some value of ipublic static int indexOf(int[] array,
int target)
Returns the index of the first appearance of the value target in array.
array - an array of int values, possibly emptytarget - a primitive int valuei for which array[i] == target, or -1 if no such index exists.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.
array - the array to search for the sequence targettarget - the array to search for as a sub-sequence of arraypublic static int lastIndexOf(int[] array,
int target)
Returns the index of the last appearance of the value target in array.
array - an array of int values, possibly emptytarget - a primitive int valuei for which array[i] == target, or -1 if no such index exists.public static int min(int... array)
Returns the least value present in array.
array - a nonempty array of int valuesarray that is less than or equal to every other value in the arrayIllegalArgumentException - if array is emptypublic static int max(int... array)
Returns the greatest value present in array.
array - a nonempty array of int valuesarray that is greater than or equal to every other value in the arrayIllegalArgumentException - if array is emptypublic 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}.
arrays - zero or more int arrays@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 to get a growable buffer.
@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.
IllegalArgumentException - if bytes has fewer than 4 elements@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}).
@Beta public static Converter<String,Integer> stringConverter()
Returns a serializable converter object that converts between strings and integers using Integer.decode(java.lang.String) and Integer.toString().
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.
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, 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".
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 emptypublic 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[]).
public static int[] toArray(Collection<? extends Number> collection)
Returns an array containing each value of collection, converted to a int value in the manner of Number.intValue().
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<Integer> before 12.0)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.
backingArray - the array to back the list@Beta @Nullable @CheckForNull public static Integer tryParse(String string)
Parses the specified string as a signed decimal integer value. The ASCII character '-' (‘\u002D’) is recognized as the minus sign.
Unlike Integer.parseInt(String), this method returns null instead of throwing an exception if parsing fails. Additionally, this method only accepts ASCII digits, and returns null if non-ASCII digits are present in the string.
Note that strings prefixed with ASCII '+' are rejected, even under JDK 7, despite the change to Integer.parseInt(String) for that version.
string - the string representation of an integer valuestring, or null if string has a length of zero or cannot be parsed as an integer value@Beta @Nullable @CheckForNull public static Integer tryParse(String string, int radix)
Parses the specified string as a signed integer value using the specified radix. The ASCII character '-' (‘\u002D’) is recognized as the minus sign.
Unlike Integer.parseInt(String, int), this method returns null instead of throwing an exception if parsing fails. Additionally, this method only accepts ASCII digits, and returns null if non-ASCII digits are present in the string.
Note that strings prefixed with ASCII '+' are rejected, even under JDK 7, despite the change to Integer.parseInt(String, int) for that version.
string - the string representation of an integer valueradix - the radix to use when parsingstring using radix, or null if string has a length of zero or cannot be parsed as an integer valueIllegalArgumentException - if radix < Character.MIN_RADIX or radix > Character.MAX_RADIX