public final class Integer extends Number implements Comparable<Integer>
Integer
class wraps a value of the primitive type
int
in an object. An object of type Integer
contains a single field whose type is int
.
In addition, this class provides several methods for converting
an int
to a String
and a String
to an
int
, as well as other constants and methods useful when
dealing with an int
.
Implementation note: The implementations of the "bit twiddling"
methods (such as highestOneBit
and
numberOfTrailingZeros
) are
based on material from Henry S. Warren, Jr.'s Hacker's
Delight, (Addison Wesley, 2002).
Modifier and Type  Field and Description 

static int 
MAX_VALUE
A constant holding the maximum value an
int can
have, 2^{31}1. 
static int 
MIN_VALUE
A constant holding the minimum value an
int can
have, 2^{31}. 
static int 
SIZE
The number of bits used to represent an
int value in two's
complement binary form. 
static Class<Integer> 
TYPE
The
Class instance representing the primitive type
int . 
Constructor and Description 

Integer(int value)
Constructs a newly allocated
Integer object that
represents the specified int value. 
Integer(String s)
Constructs a newly allocated
Integer object that
represents the int value indicated by the
String parameter. 
Modifier and Type  Method and Description 

static int 
bitCount(int i)
Returns the number of onebits in the two's complement binary
representation of the specified
int value. 
byte 
byteValue()
Returns the value of this
Integer as a
byte . 
static int 
compare(int x,
int y)
Compares two
int values numerically. 
int 
compareTo(Integer anotherInteger)
Compares two
Integer objects numerically. 
static Integer 
decode(String nm)
Decodes a
String into an Integer . 
double 
doubleValue()
Returns the value of this
Integer as a
double . 
boolean 
equals(Object obj)
Compares this object to the specified object.

float 
floatValue()
Returns the value of this
Integer as a
float . 
static Integer 
getInteger(String nm)
Determines the integer value of the system property with the
specified name.

static Integer 
getInteger(String nm,
int val)
Determines the integer value of the system property with the
specified name.

static Integer 
getInteger(String nm,
Integer val)
Returns the integer value of the system property with the
specified name.

int 
hashCode()
Returns a hash code for this
Integer . 
static int 
highestOneBit(int i)
Returns an
int value with at most a single onebit, in the
position of the highestorder ("leftmost") onebit in the specified
int value. 
int 
intValue()
Returns the value of this
Integer as an
int . 
long 
longValue()
Returns the value of this
Integer as a
long . 
static int 
lowestOneBit(int i)
Returns an
int value with at most a single onebit, in the
position of the lowestorder ("rightmost") onebit in the specified
int value. 
static int 
numberOfLeadingZeros(int i)
Returns the number of zero bits preceding the highestorder
("leftmost") onebit in the two's complement binary representation
of the specified
int value. 
static int 
numberOfTrailingZeros(int i)
Returns the number of zero bits following the lowestorder ("rightmost")
onebit in the two's complement binary representation of the specified
int value. 
static int 
parseInt(String s)
Parses the string argument as a signed decimal integer.

static int 
parseInt(String s,
int radix)
Parses the string argument as a signed integer in the radix
specified by the second argument.

static int 
reverse(int i)
Returns the value obtained by reversing the order of the bits in the
two's complement binary representation of the specified
int
value. 
static int 
reverseBytes(int i)
Returns the value obtained by reversing the order of the bytes in the
two's complement representation of the specified
int value. 
static int 
rotateLeft(int i,
int distance)
Returns the value obtained by rotating the two's complement binary
representation of the specified
int value left by the
specified number of bits. 
static int 
rotateRight(int i,
int distance)
Returns the value obtained by rotating the two's complement binary
representation of the specified
int value right by the
specified number of bits. 
short 
shortValue()
Returns the value of this
Integer as a
short . 
static int 
signum(int i)
Returns the signum function of the specified
int value. 
static String 
toBinaryString(int i)
Returns a string representation of the integer argument as an
unsigned integer in base 2.

static String 
toHexString(int i)
Returns a string representation of the integer argument as an
unsigned integer in base 16.

static String 
toOctalString(int i)
Returns a string representation of the integer argument as an
unsigned integer in base 8.

String 
toString()
Returns a
String object representing this
Integer 's value. 
static String 
toString(int i)
Returns a
String object representing the
specified integer. 
static String 
toString(int i,
int radix)
Returns a string representation of the first argument in the
radix specified by the second argument.

static Integer 
valueOf(int i)
Returns an
Integer instance representing the specified
int value. 
static Integer 
valueOf(String s)
Returns an
Integer object holding the
value of the specified String . 
static Integer 
valueOf(String s,
int radix)
Returns an
Integer object holding the value
extracted from the specified String when parsed
with the radix given by the second argument. 
public static final int MIN_VALUE
int
can
have, 2^{31}.public static final int MAX_VALUE
int
can
have, 2^{31}1.public static final Class<Integer> TYPE
Class
instance representing the primitive type
int
.public static final int SIZE
int
value in two's
complement binary form.public Integer(int value)
Integer
object that
represents the specified int
value.value
 the value to be represented by the
Integer
object.public Integer(String s) throws NumberFormatException
Integer
object that
represents the int
value indicated by the
String
parameter. The string is converted to an
int
value in exactly the manner used by the
parseInt
method for radix 10.s
 the String
to be converted to an
Integer
.NumberFormatException
 if the String
does not
contain a parsable integer.parseInt(java.lang.String, int)
public static String toString(int i, int radix)
If the radix is smaller than Character.MIN_RADIX
or larger than Character.MAX_RADIX
, then the radix
10
is used instead.
If the first argument is negative, the first element of the
result is the ASCII minus character ''
('\u002D'
). If the first argument is not
negative, no sign character appears in the result.
The remaining characters of the result represent the magnitude
of the first argument. If the magnitude is zero, it is
represented by a single zero character '0'
('\u0030'
); otherwise, the first character of
the representation of the magnitude will not be the zero
character. The following ASCII characters are used as digits:
0123456789abcdefghijklmnopqrstuvwxyz
These are '\u0030'
through
'\u0039'
and '\u0061'
through
'\u007A'
. If radix
is
N, then the first N of these characters
are used as radixN digits in the order shown. Thus,
the digits for hexadecimal (radix 16) are
0123456789abcdef
. If uppercase letters are
desired, the String.toUpperCase()
method may
be called on the result:
Integer.toString(n, 16).toUpperCase()
i
 an integer to be converted to a string.radix
 the radix to use in the string representation.Character.MAX_RADIX
,
Character.MIN_RADIX
public static String toHexString(int i)
The unsigned integer value is the argument plus 2^{32}
if the argument is negative; otherwise, it is equal to the
argument. This value is converted to a string of ASCII digits
in hexadecimal (base 16) with no extra leading
0
s. If the unsigned magnitude is zero, it is
represented by a single zero character '0'
('\u0030'
); otherwise, the first character of
the representation of the unsigned magnitude will not be the
zero character. The following characters are used as
hexadecimal digits:
0123456789abcdef
These are the characters '\u0030'
through
'\u0039'
and '\u0061'
through
'\u0066'
. If uppercase letters are
desired, the String.toUpperCase()
method may
be called on the result:
Integer.toHexString(n).toUpperCase()
i
 an integer to be converted to a string.public static String toOctalString(int i)
The unsigned integer value is the argument plus 2^{32}
if the argument is negative; otherwise, it is equal to the
argument. This value is converted to a string of ASCII digits
in octal (base 8) with no extra leading 0
s.
If the unsigned magnitude is zero, it is represented by a
single zero character '0'
('\u0030'
); otherwise, the first character of
the representation of the unsigned magnitude will not be the
zero character. The following characters are used as octal
digits:
01234567
These are the characters '\u0030'
through
'\u0037'
.i
 an integer to be converted to a string.public static String toBinaryString(int i)
The unsigned integer value is the argument plus 2^{32}
if the argument is negative; otherwise it is equal to the
argument. This value is converted to a string of ASCII digits
in binary (base 2) with no extra leading 0
s.
If the unsigned magnitude is zero, it is represented by a
single zero character '0'
('\u0030'
); otherwise, the first character of
the representation of the unsigned magnitude will not be the
zero character. The characters '0'
('\u0030'
) and '1'
('\u0031'
) are used as binary digits.
i
 an integer to be converted to a string.public static String toString(int i)
String
object representing the
specified integer. The argument is converted to signed decimal
representation and returned as a string, exactly as if the
argument and radix 10 were given as arguments to the toString(int, int)
method.i
 an integer to be converted.public static int parseInt(String s, int radix) throws NumberFormatException
Character.digit(char, int)
returns a
nonnegative value), except that the first character may be an
ASCII minus sign ''
('\u002D'
) to
indicate a negative value or an ASCII plus sign '+'
('\u002B'
) to indicate a positive value. The
resulting integer value is returned.
An exception of type NumberFormatException
is
thrown if any of the following situations occurs:
null
or is a string of
length zero.
Character.MIN_RADIX
or
larger than Character.MAX_RADIX
.
''
('\u002D'
) or plus sign
'+'
('\u002B'
) provided that the
string is longer than length 1.
int
.
Examples:
parseInt("0", 10) returns 0 parseInt("473", 10) returns 473 parseInt("+42", 10) returns 42 parseInt("0", 10) returns 0 parseInt("FF", 16) returns 255 parseInt("1100110", 2) returns 102 parseInt("2147483647", 10) returns 2147483647 parseInt("2147483648", 10) returns 2147483648 parseInt("2147483648", 10) throws a NumberFormatException parseInt("99", 8) throws a NumberFormatException parseInt("Kona", 10) throws a NumberFormatException parseInt("Kona", 27) returns 411787
s
 the String
containing the integer
representation to be parsedradix
 the radix to be used while parsing s
.NumberFormatException
 if the String
does not contain a parsable int
.public static int parseInt(String s) throws NumberFormatException
''
('\u002D'
) to indicate a negative value or an
ASCII plus sign '+'
('\u002B'
) to
indicate a positive value. The resulting integer value is
returned, exactly as if the argument and the radix 10 were
given as arguments to the parseInt(java.lang.String,
int)
method.s
 a String
containing the int
representation to be parsedNumberFormatException
 if the string does not contain a
parsable integer.public static Integer valueOf(String s, int radix) throws NumberFormatException
Integer
object holding the value
extracted from the specified String
when parsed
with the radix given by the second argument. The first argument
is interpreted as representing a signed integer in the radix
specified by the second argument, exactly as if the arguments
were given to the parseInt(java.lang.String, int)
method. The result is an Integer
object that
represents the integer value specified by the string.
In other words, this method returns an Integer
object equal to the value of:
new Integer(Integer.parseInt(s, radix))
s
 the string to be parsed.radix
 the radix to be used in interpreting s
Integer
object holding the value
represented by the string argument in the specified
radix.NumberFormatException
 if the String
does not contain a parsable int
.public static Integer valueOf(String s) throws NumberFormatException
Integer
object holding the
value of the specified String
. The argument is
interpreted as representing a signed decimal integer, exactly
as if the argument were given to the parseInt(java.lang.String)
method. The result is an
Integer
object that represents the integer value
specified by the string.
In other words, this method returns an Integer
object equal to the value of:
new Integer(Integer.parseInt(s))
s
 the string to be parsed.Integer
object holding the value
represented by the string argument.NumberFormatException
 if the string cannot be parsed
as an integer.public static Integer valueOf(int i)
Integer
instance representing the specified
int
value. If a new Integer
instance is not
required, this method should generally be used in preference to
the constructor Integer(int)
, as this method is likely
to yield significantly better space and time performance by
caching frequently requested values.
This method will always cache values in the range 128 to 127,
inclusive, and may cache other values outside of this range.i
 an int
value.Integer
instance representing i
.public byte byteValue()
Integer
as a
byte
.public short shortValue()
Integer
as a
short
.shortValue
in class Number
short
.public int intValue()
Integer
as an
int
.public long longValue()
Integer
as a
long
.public float floatValue()
Integer
as a
float
.floatValue
in class Number
float
.public double doubleValue()
Integer
as a
double
.doubleValue
in class Number
double
.public String toString()
String
object representing this
Integer
's value. The value is converted to signed
decimal representation and returned as a string, exactly as if
the integer value were given as an argument to the toString(int)
method.public int hashCode()
Integer
.hashCode
in class Object
int
value represented by this
Integer
object.Object.equals(java.lang.Object)
,
System.identityHashCode(java.lang.Object)
public boolean equals(Object obj)
true
if and only if the argument is not
null
and is an Integer
object that
contains the same int
value as this object.equals
in class Object
obj
 the object to compare with.true
if the objects are the same;
false
otherwise.Object.hashCode()
,
HashMap
public static Integer getInteger(String nm)
The first argument is treated as the name of a system property.
System properties are accessible through the
System.getProperty(java.lang.String)
method. The
string value of this property is then interpreted as an integer
value and an Integer
object representing this value is
returned. Details of possible numeric formats can be found with
the definition of getProperty
.
If there is no property with the specified name, if the specified name
is empty or null
, or if the property does not have
the correct numeric format, then null
is returned.
In other words, this method returns an Integer
object equal to the value of:
getInteger(nm, null)
nm
 property name.Integer
value of the property.System.getProperty(java.lang.String)
,
System.getProperty(java.lang.String, java.lang.String)
public static Integer getInteger(String nm, int val)
The first argument is treated as the name of a system property.
System properties are accessible through the System.getProperty(java.lang.String)
method. The
string value of this property is then interpreted as an integer
value and an Integer
object representing this value is
returned. Details of possible numeric formats can be found with
the definition of getProperty
.
The second argument is the default value. An Integer
object
that represents the value of the second argument is returned if there
is no property of the specified name, if the property does not have
the correct numeric format, or if the specified name is empty or
null
.
In other words, this method returns an Integer
object
equal to the value of:
getInteger(nm, new Integer(val))
but in practice it may be implemented in a manner such as:
to avoid the unnecessary allocation of anInteger result = getInteger(nm, null); return (result == null) ? new Integer(val) : result;
Integer
object when the default value is not needed.nm
 property name.val
 default value.Integer
value of the property.System.getProperty(java.lang.String)
,
System.getProperty(java.lang.String, java.lang.String)
public static Integer getInteger(String nm, Integer val)
System.getProperty(java.lang.String)
method.
The string value of this property is then interpreted as an
integer value, as per the Integer.decode
method,
and an Integer
object representing this value is
returned.
0x
or the ASCII character #
, not
followed by a minus sign, then the rest of it is parsed as a
hexadecimal integer exactly as by the method
valueOf(java.lang.String, int)
with radix 16.
0
followed by another character, it is parsed as an
octal integer exactly as by the method
valueOf(java.lang.String, int)
with radix 8.
valueOf(java.lang.String, int)
with radix 10.
The second argument is the default value. The default value is
returned if there is no property of the specified name, if the
property does not have the correct numeric format, or if the
specified name is empty or null
.
nm
 property name.val
 default value.Integer
value of the property.System.getProperty(java.lang.String)
,
System.getProperty(java.lang.String, java.lang.String)
,
decode(java.lang.String)
public static Integer decode(String nm) throws NumberFormatException
String
into an Integer
.
Accepts decimal, hexadecimal, and octal numbers given
by the following grammar:
DecimalNumeral, HexDigits, and OctalDigits are as defined in section 3.10.1 of The Java™ Language Specification, except that underscores are not accepted between digits.
 DecodableString:
 Sign_{opt} DecimalNumeral
 Sign_{opt}
0x
HexDigits Sign_{opt}
0X
HexDigits Sign_{opt}
#
HexDigits Sign_{opt}
0
OctalDigits
 Sign:

+
The sequence of characters following an optional
sign and/or radix specifier ("0x
", "0X
",
"#
", or leading zero) is parsed as by the Integer.parseInt
method with the indicated radix (10, 16, or
8). This sequence of characters must represent a positive
value or a NumberFormatException
will be thrown. The
result is negated if first character of the specified String
is the minus sign. No whitespace characters are
permitted in the String
.
nm
 the String
to decode.Integer
object holding the int
value represented by nm
NumberFormatException
 if the String
does not
contain a parsable integer.parseInt(java.lang.String, int)
public int compareTo(Integer anotherInteger)
Integer
objects numerically.compareTo
in interface Comparable<Integer>
anotherInteger
 the Integer
to be compared.0
if this Integer
is
equal to the argument Integer
; a value less than
0
if this Integer
is numerically less
than the argument Integer
; and a value greater
than 0
if this Integer
is numerically
greater than the argument Integer
(signed
comparison).public static int compare(int x, int y)
int
values numerically.
The value returned is identical to what would be returned by:
Integer.valueOf(x).compareTo(Integer.valueOf(y))
x
 the first int
to comparey
 the second int
to compare0
if x == y
;
a value less than 0
if x < y
; and
a value greater than 0
if x > y
public static int highestOneBit(int i)
int
value with at most a single onebit, in the
position of the highestorder ("leftmost") onebit in the specified
int
value. Returns zero if the specified value has no
onebits in its two's complement binary representation, that is, if it
is equal to zero.int
value with a single onebit, in the position
of the highestorder onebit in the specified value, or zero if
the specified value is itself equal to zero.public static int lowestOneBit(int i)
int
value with at most a single onebit, in the
position of the lowestorder ("rightmost") onebit in the specified
int
value. Returns zero if the specified value has no
onebits in its two's complement binary representation, that is, if it
is equal to zero.int
value with a single onebit, in the position
of the lowestorder onebit in the specified value, or zero if
the specified value is itself equal to zero.public static int numberOfLeadingZeros(int i)
int
value. Returns 32 if the
specified value has no onebits in its two's complement representation,
in other words if it is equal to zero.
Note that this method is closely related to the logarithm base 2.
For all positive int
values x:
31  numberOfLeadingZeros(x)
32  numberOfLeadingZeros(x  1)
int
value, or 32 if the value
is equal to zero.public static int numberOfTrailingZeros(int i)
int
value. Returns 32 if the specified value has no
onebits in its two's complement representation, in other words if it is
equal to zero.int
value, or 32 if the value is equal
to zero.public static int bitCount(int i)
int
value. This function is
sometimes referred to as the population count.int
value.public static int rotateLeft(int i, int distance)
int
value left by the
specified number of bits. (Bits shifted out of the left hand, or
highorder, side reenter on the right, or loworder.)
Note that left rotation with a negative distance is equivalent to
right rotation: rotateLeft(val, distance) == rotateRight(val,
distance)
. Note also that rotation by any multiple of 32 is a
noop, so all but the last five bits of the rotation distance can be
ignored, even if the distance is negative: rotateLeft(val,
distance) == rotateLeft(val, distance & 0x1F)
.
int
value left by the
specified number of bits.public static int rotateRight(int i, int distance)
int
value right by the
specified number of bits. (Bits shifted out of the right hand, or
loworder, side reenter on the left, or highorder.)
Note that right rotation with a negative distance is equivalent to
left rotation: rotateRight(val, distance) == rotateLeft(val,
distance)
. Note also that rotation by any multiple of 32 is a
noop, so all but the last five bits of the rotation distance can be
ignored, even if the distance is negative: rotateRight(val,
distance) == rotateRight(val, distance & 0x1F)
.
int
value right by the
specified number of bits.public static int reverse(int i)
int
value.int
value.public static int signum(int i)
int
value. (The
return value is 1 if the specified value is negative; 0 if the
specified value is zero; and 1 if the specified value is positive.)int
value.public static int reverseBytes(int i)
int
value.int
value. Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developertargeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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