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Integer

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).

Summary

Constants

int BYTES

The number of bytes used to represent a int value in two's complement binary form.

int MAX_VALUE

A constant holding the maximum value an int can have, 231-1.

int MIN_VALUE

A constant holding the minimum value an int can have, -231.

int SIZE

The number of bits used to represent an int value in two's complement binary form.

Fields

public static final Class<Integer> TYPE

The Class instance representing the primitive type int.

Public constructors

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.

Public methods

static int bitCount(int i)

Returns the number of one-bits 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, 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 Integer.

static int hashCode(int value)

Returns a hash code for a int value; compatible with Integer.hashCode().

static int highestOneBit(int i)

Returns an int value with at most a single one-bit, in the position of the highest-order ("leftmost") one-bit 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 one-bit, in the position of the lowest-order ("rightmost") one-bit in the specified int value.

static int max(int a, int b)

Returns the greater of two int values as if by calling Math.max.

static int min(int a, int b)

Returns the smaller of two int values as if by calling Math.min.

static int numberOfLeadingZeros(int i)

Returns the number of zero bits preceding the highest-order ("leftmost") one-bit 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 lowest-order ("rightmost") one-bit in the two's complement binary representation of the specified int value.

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 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 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 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(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.

static Integer valueOf(int i)

Returns an Integer instance representing the specified int value.

Inherited methods

From class java.lang.Number
From class java.lang.Object
From interface java.lang.Comparable

Constants

BYTES

Added in API level 24
int BYTES

The number of bytes used to represent a int value in two's complement binary form.

Constant Value: 4 (0x00000004)

MAX_VALUE

Added in API level 1
int MAX_VALUE

A constant holding the maximum value an int can have, 231-1.

Constant Value: 2147483647 (0x7fffffff)

MIN_VALUE

Added in API level 1
int MIN_VALUE

A constant holding the minimum value an int can have, -231.

Constant Value: -2147483648 (0x80000000)

SIZE

Added in API level 1
int SIZE

The number of bits used to represent an int value in two's complement binary form.

Constant Value: 32 (0x00000020)

Fields

TYPE

Added in API level 1
Class<Integer> TYPE

The Class instance representing the primitive type int.

Public constructors

Integer

Added in API level 1
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

Added in API level 1
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:

Public methods

bitCount

Added in API level 1
int bitCount (int i)

Returns the number of one-bits 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 one-bits in the two's complement binary representation of the specified int value.

byteValue

Added in API level 1
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.

compare

Added in API level 19
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

compareTo

Added in API level 1
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).

decode

Added in API level 1
Integer decode (String nm)

Decodes a String into an Integer. Accepts decimal, hexadecimal, and octal numbers given by the following grammar:

DecodableString:
Signopt DecimalNumeral
Signopt 0x HexDigits
Signopt 0X HexDigits
Signopt # HexDigits
Signopt 0 OctalDigits

Sign:
-
+
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.

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:

doubleValue

Added in API level 1
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.

equals

Added in API level 1
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.

floatValue

Added in API level 1
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.

getInteger

Added in API level 1
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.

  • If the property value begins with the two ASCII characters 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.
  • If the property value begins with the ASCII character 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.
  • Otherwise, the property value is parsed as a decimal integer exactly as by the method 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.

See also:

getInteger

Added in API level 1
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.

See also:

getInteger

Added in API level 1
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:
 Integer result = getInteger(nm, null);
 return (result == null) ? new Integer(val) : result;
 
to avoid the unnecessary allocation of an 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.

See also:

hashCode

Added in API level 1
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.

hashCode

Added in API level 24
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.

highestOneBit

Added in API level 1
int highestOneBit (int i)

Returns an int value with at most a single one-bit, in the position of the highest-order ("leftmost") one-bit in the specified int value. Returns zero if the specified value has no one-bits 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 one-bit, in the position of the highest-order one-bit in the specified value, or zero if the specified value is itself equal to zero.

intValue

Added in API level 1
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.

longValue

Added in API level 1
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.

lowestOneBit

Added in API level 1
int lowestOneBit (int i)

Returns an int value with at most a single one-bit, in the position of the lowest-order ("rightmost") one-bit in the specified int value. Returns zero if the specified value has no one-bits 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 one-bit, in the position of the lowest-order one-bit in the specified value, or zero if the specified value is itself equal to zero.

max

Added in API level 24
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:

min

Added in API level 24
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:

numberOfLeadingZeros

Added in API level 1
int numberOfLeadingZeros (int i)

Returns the number of zero bits preceding the highest-order ("leftmost") one-bit in the two's complement binary representation of the specified int value. Returns 32 if the specified value has no one-bits 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:

  • floor(log2(x)) = 31 - numberOfLeadingZeros(x)
  • ceil(log2(x)) = 32 - numberOfLeadingZeros(x - 1)

Parameters
i int
Returns
int the number of zero bits preceding the highest-order ("leftmost") one-bit in the two's complement binary representation of the specified int value, or 32 if the value is equal to zero.

numberOfTrailingZeros

Added in API level 1
int numberOfTrailingZeros (int i)

Returns the number of zero bits following the lowest-order ("rightmost") one-bit in the two's complement binary representation of the specified int value. Returns 32 if the specified value has no one-bits 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 lowest-order ("rightmost") one-bit in the two's complement binary representation of the specified int value, or 32 if the value is equal to zero.

parseInt

Added in API level 1
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:

  • The first argument is null or is a string of length zero.
  • The radix is either smaller than MIN_RADIX or larger than MAX_RADIX.
  • Any character of the string is not a digit of the specified radix, except that the first character may be a minus sign '-' ('\u002D') or plus sign '+' ('\u002B') provided that the string is longer than length 1.
  • The value represented by the string is not a value of type 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.

parseInt

Added in API level 1
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.

reverse

Added in API level 1
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.

reverseBytes

Added in API level 1
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.

rotateLeft

Added in API level 1
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 high-order, side reenter on the right, or low-order.)

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 no-op, 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.

rotateRight

Added in API level 1
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 low-order, side reenter on the left, or high-order.)

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 no-op, 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.

shortValue

Added in API level 1
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.

signum

Added in API level 1
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.

sum

Added in API level 24
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:

toBinaryString

Added in API level 1
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 232 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 0s. 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).

toHexString

Added in API level 1
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 232 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 0s. 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).

toOctalString

Added in API level 1
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 232 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 0s.

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).

toString

Added in API level 1
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.

toString

Added in API level 1
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.

toString

Added in API level 1
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.

See also:

valueOf

Added in API level 1
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.

valueOf

Added in API level 1
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.

valueOf

Added in API level 1
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.
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