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 tointprimitives, that are not already found in eitherIntegerorArrays.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 intBYTESThe number of bytes required to represent a primitiveintvalue.static intMAX_POWER_OF_TWOThe 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 intcheckedCast(long value)Returns theintvalue that is equal tovalue, if possible.static intcompare(int a, int b)Compares the two specifiedintvalues.static int[]concat(int[]... arrays)Returns the values from each provided array combined into a single array.static booleancontains(int[] array, int target)Returnstrueiftargetis 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 intfromByteArray(byte[] bytes)Returns theintvalue whose big-endian representation is stored in the first 4 bytes ofbytes; equivalent toByteBuffer.wrap(bytes).getInt().static intfromBytes(byte b1, byte b2, byte b3, byte b4)Returns theintvalue whose byte representation is the given 4 bytes, in big-endian order; equivalent toInts.fromByteArray(new byte[] {b1, b2, b3, b4}).static inthashCode(int value)Returns a hash code forvalue; equal to the result of invoking((Integer) value).hashCode().static intindexOf(int[] array, int target)Returns the index of the first appearance of the valuetargetinarray.static intindexOf(int[] array, int[] target)Returns the start position of the first occurrence of the specifiedtargetwithinarray, or-1if there is no such occurrence.static java.lang.Stringjoin(java.lang.String separator, int... array)Returns a string containing the suppliedintvalues separated byseparator.static intlastIndexOf(int[] array, int target)Returns the index of the last appearance of the valuetargetinarray.static java.util.Comparator<int[]>lexicographicalComparator()Returns a comparator that compares twointarrays lexicographically.static intmax(int... array)Returns the greatest value present inarray.static intmin(int... array)Returns the least value present inarray.static intsaturatedCast(long value)Returns theintnearest 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 aintvalue in the manner ofNumber.intValue().static byte[]toByteArray(int value)Returns a big-endian representation ofvaluein a 4-element byte array; equivalent toByteBuffer.allocate(4).putInt(value).array().static java.lang.IntegertryParse(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 primitiveintvalue.- See Also:
- Constant Field Values
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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 primitiveintvalue- Returns:
- a hash code for the value
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checkedCast
public static int checkedCast(long value)
Returns theintvalue that is equal tovalue, if possible.- Parameters:
value- any value in the range of theinttype- Returns:
- the
intvalue that equalsvalue - Throws:
java.lang.IllegalArgumentException- ifvalueis greater thanInteger.MAX_VALUEor less thanInteger.MIN_VALUE
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saturatedCast
public static int saturatedCast(long value)
Returns theintnearest in value tovalue.- Parameters:
value- anylongvalue- Returns:
- the same value cast to
intif it is in the range of theinttype,Integer.MAX_VALUEif it is too large, orInteger.MIN_VALUEif it is too small
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compare
public static int compare(int a, int b)Compares the two specifiedintvalues. 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 firstintto compareb- the secondintto compare- Returns:
- a negative value if
ais less thanb; a positive value ifais greater thanb; or zero if they are equal
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contains
public static boolean contains(int[] array, int target)Returnstrueiftargetis present as an element anywhere inarray.- Parameters:
array- an array ofintvalues, possibly emptytarget- a primitiveintvalue- Returns:
trueifarray[i] == targetfor 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 valuetargetinarray.- Parameters:
array- an array ofintvalues, possibly emptytarget- a primitiveintvalue- Returns:
- the least index
ifor whicharray[i] == target, or-1if 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 specifiedtargetwithinarray, or-1if there is no such occurrence.More formally, returns the lowest index
isuch thatjava.util.Arrays.copyOfRange(array, i, i + target.length)contains exactly the same elements astarget.- Parameters:
array- the array to search for the sequencetargettarget- 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 valuetargetinarray.- Parameters:
array- an array ofintvalues, possibly emptytarget- a primitiveintvalue- Returns:
- the greatest index
ifor whicharray[i] == target, or-1if 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 ofintvalues- Returns:
- the value present in
arraythat is less than or equal to every other value in the array - Throws:
java.lang.IllegalArgumentException- ifarrayis empty
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max
public static int max(int... array)
Returns the greatest value present inarray.- Parameters:
array- a nonempty array ofintvalues- Returns:
- the value present in
arraythat is greater than or equal to every other value in the array - Throws:
java.lang.IllegalArgumentException- ifarrayis 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 moreintarrays- 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 ofvaluein a 4-element byte array; equivalent toByteBuffer.allocate(4).putInt(value).array(). For example, the input value0x12131415would 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
ByteBufferinstance, or useByteStreams.newDataOutput()to get a growable buffer.
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fromByteArray
@GwtIncompatible("doesn\'t work") public static int fromByteArray(byte[] bytes)
Returns theintvalue 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 theintvalue0x12131415.Arguably, it's preferable to use
ByteBuffer; that library exposes much more flexibility at little cost in readability.- Throws:
java.lang.IllegalArgumentException- ifbyteshas 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 theintvalue 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. Ifarrayalready has a length of at leastminLength, it is returned directly. Otherwise, a new array of sizeminLength + paddingis 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- ifminLengthorpaddingis negative
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join
public static java.lang.String join(java.lang.String separator, int... array)Returns a string containing the suppliedintvalues 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 ofintvalues, possibly empty
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lexicographicalComparator
public static java.util.Comparator<int[]> lexicographicalComparator()
Returns a comparator that compares twointarrays 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 aintvalue 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 ofNumberinstances- Returns:
- an array containing the same values as
collection, in the same order, converted to primitives - Throws:
java.lang.NullPointerException- ifcollectionor 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 tonullwill result in aNullPointerException.The returned list maintains the values, but not the identities, of
Integerobjects 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 returnsnullinstead of throwing an exception if parsing fails. Additionally, this method only accepts ASCII digits, and returnsnullif 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, ornullifstringhas a length of zero or cannot be parsed as an integer value - Since:
- 11.0
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