public final class Integer
extends Number
implements Comparable<Integer>
java.lang.Object  
↳  java.lang.Number  
↳  java.lang.Integer 
The 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).
Constants 


int 
BYTES The number of bytes used to represent a 
int 
MAX_VALUE A constant holding the maximum value an 
int 
MIN_VALUE A constant holding the minimum value an 
int 
SIZE The number of bits used to represent an 
Fields 


public static final Class<Integer> 
TYPE The 
Public constructors 


Integer(int value) Constructs a newly allocated 

Integer(String s) Constructs a newly allocated 
Public methods 


static int 
bitCount(int i) Returns the number of onebits in the two's complement binary representation of the specified 
byte 
byteValue() Returns the value of this 
static int 
compare(int x, int y) Compares two 
int 
compareTo(Integer anotherInteger) Compares two 
static Integer 
decode(String nm) Decodes a 
double 
doubleValue() Returns the value of this 
boolean 
equals(Object obj) Compares this object to the specified object. 
float 
floatValue() Returns the value of this 
static Integer 
getInteger(String nm, Integer val) Returns the integer value of the system property with the specified name. 
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. 
int 
hashCode() Returns a hash code for this 
static int 
hashCode(int value) Returns a hash code for a 
static int 
highestOneBit(int i) Returns an 
int 
intValue() Returns the value of this 
long 
longValue() Returns the value of this 
static int 
lowestOneBit(int i) Returns an 
static int 
max(int a, int b) Returns the greater of two 
static int 
min(int a, int b) Returns the smaller of two 
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 
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 
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 
parseInt(String s) Parses the string argument as a signed decimal integer. 
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 
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 
static int 
rotateLeft(int i, int distance) Returns the value obtained by rotating the two's complement binary representation of the specified 
static int 
rotateRight(int i, int distance) Returns the value obtained by rotating the two's complement binary representation of the specified 
short 
shortValue() Returns the value of this 
static int 
signum(int i) Returns the signum function of the specified 
static int 
sum(int a, int b) Adds two integers together as per the + operator. 
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 
static String 
toString(int i) Returns a 
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(String s) Returns an 
static Integer 
valueOf(String s, int radix) Returns an 
static Integer 
valueOf(int i) Returns an 
Inherited methods 


From class java.lang.Number


From class java.lang.Object


From interface java.lang.Comparable

int BYTES
The number of bytes used to represent a int
value in two's complement binary form.
Constant Value: 4 (0x00000004)
int MAX_VALUE
A constant holding the maximum value an int
can have, 2^{31}1.
Constant Value: 2147483647 (0x7fffffff)
int MIN_VALUE
A constant holding the minimum value an int
can have, 2^{31}.
Constant Value: 2147483648 (0x80000000)
int SIZE
The number of bits used to represent an int
value in two's complement binary form.
Constant Value: 32 (0x00000020)
Class<Integer> TYPE
The Class
instance representing the primitive type int
.
Integer (int value)
Constructs a newly allocated Integer
object that represents the specified int
value.
Parameters  

value 
int : the value to be represented by the Integer object. 
Integer (String s)
Constructs a newly allocated 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.
Parameters  

s 
String : the String to be converted to an Integer . 
Throws  

NumberFormatException 
if the String does not contain a parsable integer. 
See also:
int bitCount (int i)
Returns the number of onebits in the two's complement binary representation of the specified int
value. This function is sometimes referred to as the population count.
Parameters  

i 
int

Returns  

int 
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
.
Returns  

byte 
the numeric value represented by this object after conversion to type byte . 
int compare (int x, int y)
Compares two int
values numerically. The value returned is identical to what would be returned by:
Integer.valueOf(x).compareTo(Integer.valueOf(y))
Parameters  

x 
int : the first int to compare 
y 
int : the second int to compare 
Returns  

int 
the value 0 if x == y ; a value less than 0 if x < y ; and a value greater than 0 if x > y 
int compareTo (Integer anotherInteger)
Compares two Integer
objects numerically.
Parameters  

anotherInteger 
Integer : the Integer to be compared. 
Returns  

int 
the value 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). 
Integer decode (String nm)
Decodes a 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
.
Parameters  

nm 
String : the String to decode. 
Returns  

Integer 
an Integer object holding the int value represented by nm 
Throws  

NumberFormatException 
if the String does not contain a parsable integer. 
See also:
double doubleValue ()
Returns the value of this Integer
as a double
.
Returns  

double 
the numeric value represented by this object after conversion to type double . 
boolean equals (Object obj)
Compares this object to the specified object. The result is true
if and only if the argument is not null
and is an Integer
object that contains the same int
value as this object.
Parameters  

obj 
Object : the object to compare with. 
Returns  

boolean 
true if the objects are the same; false otherwise. 
float floatValue ()
Returns the value of this Integer
as a float
.
Returns  

float 
the numeric value represented by this object after conversion to type float . 
Integer getInteger (String nm, Integer val)
Returns the integer value of the system property with the specified name. The first argument is treated as the name of a system property. System properties are accessible through the 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
.
Parameters  

nm 
String : property name. 
val 
Integer : default value. 
Returns  

Integer 
the Integer value of the property. 
Integer getInteger (String nm)
Determines the integer value of the system property with the specified name.
The first argument is treated as the name of a system property. System properties are accessible through the 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)
Parameters  

nm 
String : property name. 
Returns  

Integer 
the Integer value of the property. 
Integer getInteger (String nm, int val)
Determines the integer value of the system property with the specified name.
The first argument is treated as the name of a system property. System properties are accessible through the 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.
Parameters  

nm 
String : property name. 
val 
int : default value. 
Returns  

Integer 
the Integer value of the property. 
int hashCode ()
Returns a hash code for this Integer
.
Returns  

int 
a hash code value for this object, equal to the primitive int value represented by this Integer object. 
int hashCode (int value)
Returns a hash code for a int
value; compatible with Integer.hashCode()
.
Parameters  

value 
int : the value to hash 
Returns  

int 
a hash code value for a int value. 
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. Returns zero if the specified value has no onebits in its two's complement binary representation, that is, if it is equal to zero.
Parameters  

i 
int

Returns  

int 
an 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. 
int intValue ()
Returns the value of this Integer
as an int
.
Returns  

int 
the numeric value represented by this object after conversion to type int . 
long longValue ()
Returns the value of this Integer
as a long
.
Returns  

long 
the numeric value represented by this object after conversion to type long . 
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. Returns zero if the specified value has no onebits in its two's complement binary representation, that is, if it is equal to zero.
Parameters  

i 
int

Returns  

int 
an 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. 
int max (int a, int b)
Returns the greater of two int
values as if by calling Math.max
.
Parameters  

a 
int : the first operand 
b 
int : the second operand 
Returns  

int 
the greater of a and b 
See also:
int min (int a, int b)
Returns the smaller of two int
values as if by calling Math.min
.
Parameters  

a 
int : the first operand 
b 
int : the second operand 
Returns  

int 
the smaller of a and b 
See also:
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. 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)
Parameters  

i 
int

Returns  

int 
the number of zero bits preceding the highestorder ("leftmost") onebit in the two's complement binary representation of the specified int value, or 32 if the value is equal to zero. 
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. Returns 32 if the specified value has no onebits in its two's complement representation, in other words if it is equal to zero.
Parameters  

i 
int

Returns  

int 
the number of zero bits following the lowestorder ("rightmost") onebit in the two's complement binary representation of the specified int value, or 32 if the value is equal to zero. 
int parseInt (String s, int radix)
Parses the string argument as a signed integer in the radix specified by the second argument. The characters in the string must all be digits of the specified radix (as determined by whether 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. MIN_RADIX
or larger than 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
Parameters  

s 
String : the String containing the integer representation to be parsed 
radix 
int : the radix to be used while parsing s . 
Returns  

int 
the integer represented by the string argument in the specified radix. 
Throws  

NumberFormatException 
if the String does not contain a parsable int . 
int parseInt (String s)
Parses the string argument as a signed decimal integer. The characters in the string must all be decimal digits, 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, exactly as if the argument and the radix 10 were given as arguments to the parseInt(java.lang.String, int)
method.
Parameters  

s 
String : a String containing the int representation to be parsed 
Returns  

int 
the integer value represented by the argument in decimal. 
Throws  

NumberFormatException 
if the string does not contain a parsable integer. 
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.
Parameters  

i 
int

Returns  

int 
the value obtained by reversing order of the bits in the specified int value. 
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.
Parameters  

i 
int

Returns  

int 
the value obtained by reversing the bytes in the specified int value. 
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. (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)
.
Parameters  

i 
int

distance 
int

Returns  

int 
the value obtained by rotating the two's complement binary representation of the specified int value left by the specified number of bits. 
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. (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)
.
Parameters  

i 
int

distance 
int

Returns  

int 
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
.
Returns  

short 
the numeric value represented by this object after conversion to type short . 
int signum (int i)
Returns the signum function of the specified 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.)
Parameters  

i 
int

Returns  

int 
the signum function of the specified int value. 
int sum (int a, int b)
Adds two integers together as per the + operator.
Parameters  

a 
int : the first operand 
b 
int : the second operand 
Returns  

int 
the sum of a and b 
See also:
String toBinaryString (int i)
Returns a string representation of the integer argument as an unsigned integer in base 2.
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.
Parameters  

i 
int : an integer to be converted to a string. 
Returns  

String 
the string representation of the unsigned integer value represented by the argument in binary (base 2). 
String toHexString (int i)
Returns a string representation of the integer argument as an unsigned integer in base 16.
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
toUpperCase()
method may be called on the result:
Integer.toHexString(n).toUpperCase()
Parameters  

i 
int : an integer to be converted to a string. 
Returns  

String 
the string representation of the unsigned integer value represented by the argument in hexadecimal (base 16). 
String toOctalString (int i)
Returns a string representation of the integer argument as an unsigned integer in base 8.
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'
.
Parameters  

i 
int : an integer to be converted to a string. 
Returns  

String 
the string representation of the unsigned integer value represented by the argument in octal (base 8). 
String toString ()
Returns a 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.
Returns  

String 
a string representation of the value of this object in base 10. 
String toString (int i)
Returns a 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.
Parameters  

i 
int : an integer to be converted. 
Returns  

String 
a string representation of the argument in base 10. 
String toString (int i, int radix)
Returns a string representation of the first argument in the radix specified by the second argument.
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 radix
N digits in the order shown. Thus, the digits for hexadecimal (radix 16) are
0123456789abcdef
. If uppercase letters are desired, the
toUpperCase()
method may be called on the result:
Integer.toString(n, 16).toUpperCase()
Parameters  

i 
int : an integer to be converted to a string. 
radix 
int : the radix to use in the string representation. 
Returns  

String 
a string representation of the argument in the specified radix. 
Integer valueOf (String s)
Returns an 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))
Parameters  

s 
String : the string to be parsed. 
Returns  

Integer 
an Integer object holding the value represented by the string argument. 
Throws  

NumberFormatException 
if the string cannot be parsed as an integer. 
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. 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))
Parameters  

s 
String : the string to be parsed. 
radix 
int : the radix to be used in interpreting s 
Returns  

Integer 
an Integer object holding the value represented by the string argument in the specified radix. 
Throws  

NumberFormatException 
if the String does not contain a parsable int . 
Integer valueOf (int i)
Returns an 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.
Parameters  

i 
int : an int value. 
Returns  

Integer 
an Integer instance representing i . 