Class Ints
- java.lang.Object
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- com.google.common.primitives.Ints
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@GwtCompatible(emulated=true) public final class Ints extends java.lang.Object
Static utility methods pertaining toint
primitives, that are not already found in eitherInteger
orArrays
.See the Guava User Guide article on primitive utilities.
- Since:
- 1.0
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Field Summary
Fields Modifier and Type Field Description static int
BYTES
The number of bytes required to represent a primitiveint
value.static int
MAX_POWER_OF_TWO
The largest power of two that can be represented as anint
.
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static java.util.List<java.lang.Integer>
asList(int... backingArray)
Returns a fixed-size list backed by the specified array, similar toArrays.asList(Object[])
.static int
checkedCast(long value)
Returns theint
value that is equal tovalue
, if possible.static int
compare(int a, int b)
Compares the two specifiedint
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)
Returnstrue
iftarget
is present as an element anywhere inarray
.static int[]
ensureCapacity(int[] array, int minLength, int padding)
Returns an array containing the same values asarray
, but guaranteed to be of a specified minimum length.static int
fromByteArray(byte[] bytes)
Returns theint
value whose big-endian representation is stored in the first 4 bytes ofbytes
; equivalent toByteBuffer.wrap(bytes).getInt()
.static int
fromBytes(byte b1, byte b2, byte b3, byte b4)
Returns theint
value whose byte representation is the given 4 bytes, in big-endian order; equivalent toInts.fromByteArray(new byte[] {b1, b2, b3, b4})
.static int
hashCode(int value)
Returns a hash code forvalue
; 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 valuetarget
inarray
.static int
indexOf(int[] array, int[] target)
Returns the start position of the first occurrence of the specifiedtarget
withinarray
, or-1
if there is no such occurrence.static java.lang.String
join(java.lang.String separator, int... array)
Returns a string containing the suppliedint
values separated byseparator
.static int
lastIndexOf(int[] array, int target)
Returns the index of the last appearance of the valuetarget
inarray
.static java.util.Comparator<int[]>
lexicographicalComparator()
Returns a comparator that compares twoint
arrays lexicographically.static int
max(int... array)
Returns the greatest value present inarray
.static int
min(int... array)
Returns the least value present inarray
.static int
saturatedCast(long value)
Returns theint
nearest in value tovalue
.static Converter<java.lang.String,java.lang.Integer>
stringConverter()
Returns a serializable converter object that converts between strings and integers usingInteger.decode(java.lang.String)
andInteger.toString()
.static int[]
toArray(java.util.Collection<? extends java.lang.Number> collection)
Returns an array containing each value ofcollection
, converted to aint
value in the manner ofNumber.intValue()
.static byte[]
toByteArray(int value)
Returns a big-endian representation ofvalue
in a 4-element byte array; equivalent toByteBuffer.allocate(4).putInt(value).array()
.static java.lang.Integer
tryParse(java.lang.String string)
Parses the specified string as a signed decimal integer value.
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Field Detail
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BYTES
public static final int BYTES
The number of bytes required to represent a primitiveint
value.- See Also:
- Constant Field Values
-
MAX_POWER_OF_TWO
public static final int MAX_POWER_OF_TWO
The largest power of two that can be represented as anint
.- Since:
- 10.0
- See Also:
- Constant Field Values
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Method Detail
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hashCode
public static int hashCode(int value)
Returns a hash code forvalue
; equal to the result of invoking((Integer) value).hashCode()
.- Parameters:
value
- a primitiveint
value- Returns:
- a hash code for the value
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checkedCast
public static int checkedCast(long value)
Returns theint
value that is equal tovalue
, if possible.- Parameters:
value
- any value in the range of theint
type- Returns:
- the
int
value that equalsvalue
- Throws:
java.lang.IllegalArgumentException
- ifvalue
is greater thanInteger.MAX_VALUE
or less thanInteger.MIN_VALUE
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saturatedCast
public static int saturatedCast(long value)
Returns theint
nearest in value tovalue
.- Parameters:
value
- anylong
value- Returns:
- the same value cast to
int
if it is in the range of theint
type,Integer.MAX_VALUE
if it is too large, orInteger.MIN_VALUE
if it is too small
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compare
public static int compare(int a, int b)
Compares the two specifiedint
values. The sign of the value returned is the same as that of((Integer) a).compareTo(b)
.Note: projects using JDK 7 or later should use the equivalent
Integer.compare(int, int)
method instead.- Parameters:
a
- the firstint
to compareb
- the secondint
to compare- Returns:
- a negative value if
a
is less thanb
; a positive value ifa
is greater thanb
; or zero if they are equal
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contains
public static boolean contains(int[] array, int target)
Returnstrue
iftarget
is present as an element anywhere inarray
.- Parameters:
array
- an array ofint
values, possibly emptytarget
- a primitiveint
value- Returns:
true
ifarray[i] == target
for some value ofi
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indexOf
public static int indexOf(int[] array, int target)
Returns the index of the first appearance of the valuetarget
inarray
.- Parameters:
array
- an array ofint
values, possibly emptytarget
- a primitiveint
value- Returns:
- the least index
i
for whicharray[i] == target
, or-1
if no such index exists.
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indexOf
public static int indexOf(int[] array, int[] target)
Returns the start position of the first occurrence of the specifiedtarget
withinarray
, or-1
if there is no such occurrence.More formally, returns the lowest index
i
such thatjava.util.Arrays.copyOfRange(array, i, i + target.length)
contains exactly the same elements astarget
.- Parameters:
array
- the array to search for the sequencetarget
target
- the array to search for as a sub-sequence ofarray
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lastIndexOf
public static int lastIndexOf(int[] array, int target)
Returns the index of the last appearance of the valuetarget
inarray
.- Parameters:
array
- an array ofint
values, possibly emptytarget
- a primitiveint
value- Returns:
- the greatest index
i
for whicharray[i] == target
, or-1
if no such index exists.
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min
public static int min(int... array)
Returns the least value present inarray
.- Parameters:
array
- a nonempty array ofint
values- Returns:
- the value present in
array
that is less than or equal to every other value in the array - Throws:
java.lang.IllegalArgumentException
- ifarray
is empty
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max
public static int max(int... array)
Returns the greatest value present inarray
.- Parameters:
array
- a nonempty array ofint
values- Returns:
- the value present in
array
that is greater than or equal to every other value in the array - Throws:
java.lang.IllegalArgumentException
- ifarray
is empty
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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 moreint
arrays- Returns:
- a single array containing all the values from the source arrays, in order
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toByteArray
@GwtIncompatible("doesn\'t work") public static byte[] toByteArray(int value)
Returns a big-endian representation ofvalue
in a 4-element byte array; equivalent toByteBuffer.allocate(4).putInt(value).array()
. For example, the input value0x12131415
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 useByteStreams.newDataOutput()
to get a growable buffer.
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fromByteArray
@GwtIncompatible("doesn\'t work") public static int fromByteArray(byte[] bytes)
Returns theint
value whose big-endian representation is stored in the first 4 bytes ofbytes
; equivalent toByteBuffer.wrap(bytes).getInt()
. For example, the input byte array{0x12, 0x13, 0x14, 0x15, 0x33}
would yield theint
value0x12131415
.Arguably, it's preferable to use
ByteBuffer
; that library exposes much more flexibility at little cost in readability.- Throws:
java.lang.IllegalArgumentException
- ifbytes
has fewer than 4 elements
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fromBytes
@GwtIncompatible("doesn\'t work") public static int fromBytes(byte b1, byte b2, byte b3, byte b4)
Returns theint
value whose byte representation is the given 4 bytes, in big-endian order; equivalent toInts.fromByteArray(new byte[] {b1, b2, b3, b4})
.- Since:
- 7.0
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stringConverter
@Beta public static Converter<java.lang.String,java.lang.Integer> stringConverter()
Returns a serializable converter object that converts between strings and integers usingInteger.decode(java.lang.String)
andInteger.toString()
.- Since:
- 16.0
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ensureCapacity
public static int[] ensureCapacity(int[] array, int minLength, int padding)
Returns an array containing the same values asarray
, but guaranteed to be of a specified minimum length. Ifarray
already has a length of at leastminLength
, it is returned directly. Otherwise, a new array of sizeminLength + padding
is returned, containing the values ofarray
, and zeroes in the remaining places.- Parameters:
array
- the source arrayminLength
- the minimum length the returned array must guaranteepadding
- an extra amount to "grow" the array by if growth is necessary- Returns:
- an array containing the values of
array
, with guaranteed minimum lengthminLength
- Throws:
java.lang.IllegalArgumentException
- ifminLength
orpadding
is negative
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join
public static java.lang.String join(java.lang.String separator, int... array)
Returns a string containing the suppliedint
values separated byseparator
. 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 ofint
values, possibly empty
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lexicographicalComparator
public static java.util.Comparator<int[]> lexicographicalComparator()
Returns a comparator that compares twoint
arrays lexicographically. That is, it compares, usingcompare(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 withArrays.equals(int[], int[])
.- Since:
- 2.0
- See Also:
- Lexicographical order article at Wikipedia
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toArray
public static int[] toArray(java.util.Collection<? extends java.lang.Number> collection)
Returns an array containing each value ofcollection
, converted to aint
value in the manner ofNumber.intValue()
.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 ofNumber
instances- Returns:
- an array containing the same values as
collection
, in the same order, converted to primitives - Throws:
java.lang.NullPointerException
- ifcollection
or any of its elements is null- Since:
- 1.0 (parameter was
Collection<Integer>
before 12.0)
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asList
public static java.util.List<java.lang.Integer> asList(int... backingArray)
Returns a fixed-size list backed by the specified array, similar toArrays.asList(Object[])
. The list supportsList.set(int, Object)
, but any attempt to set a value tonull
will result in aNullPointerException
.The returned list maintains the values, but not the identities, of
Integer
objects written to or read from it. For example, whetherlist.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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tryParse
@Beta @CheckForNull @GwtIncompatible("TODO") public static java.lang.Integer tryParse(java.lang.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 returnsnull
instead of throwing an exception if parsing fails. Additionally, this method only accepts ASCII digits, and returnsnull
if non-ASCII digits are present in the string.Note that strings prefixed with ASCII
'+'
are rejected, even under JDK 7, despite the change toInteger.parseInt(String)
for that version.- Parameters:
string
- the string representation of an integer value- Returns:
- the integer value represented by
string
, ornull
ifstring
has a length of zero or cannot be parsed as an integer value - Since:
- 11.0
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