public final class

Integer

extends Number
implements Comparable<T>
java.lang.Object
   ↳ java.lang.Number
     ↳ java.lang.Integer

Class Overview

The wrapper for the primitive type int.

Implementation note: The "bit twiddling" methods in this class use techniques described in Henry S. Warren, Jr.'s Hacker's Delight, (Addison Wesley, 2002) and Sean Anderson's Bit Twiddling Hacks.

See Also

Summary

Constants
int MAX_VALUE Constant for the maximum int value, 231-1.
int MIN_VALUE Constant for the minimum int value, -231.
int SIZE Constant for the number of bits needed to represent an int in two's complement form.
Class<Integer> TYPE The Class object that represents the primitive type int.
Public Constructors
Integer(int value)
Constructs a new Integer with the specified primitive integer value.
Integer(String string)
Constructs a new Integer from the specified string.
Public Methods
static int bitCount(int i)
Counts the number of 1 bits in the specified integer; this is also referred to as population count.
byte byteValue()
Returns this object's value as a byte.
int compareTo(Integer object)
Compares this object to the specified integer object to determine their relative order.
static Integer decode(String string)
Parses the specified string and returns a Integer instance if the string can be decoded into an integer value.
double doubleValue()
Returns this object's value as a double.
boolean equals(Object o)
Compares this instance with the specified object and indicates if they are equal.
float floatValue()
Returns this object's value as a float.
static Integer getInteger(String string, Integer defaultValue)
Returns the Integer value of the system property identified by string.
static Integer getInteger(String string)
Returns the Integer value of the system property identified by string.
static Integer getInteger(String string, int defaultValue)
Returns the Integer value of the system property identified by string.
int hashCode()
Returns an integer hash code for this object.
static int highestOneBit(int i)
Determines the highest (leftmost) bit of the specified integer that is 1 and returns the bit mask value for that bit.
int intValue()
Gets the primitive value of this int.
long longValue()
Returns this object's value as a long.
static int lowestOneBit(int i)
Determines the lowest (rightmost) bit of the specified integer that is 1 and returns the bit mask value for that bit.
static int numberOfLeadingZeros(int i)
Determines the number of leading zeros in the specified integer prior to the highest one bit.
static int numberOfTrailingZeros(int i)
Determines the number of trailing zeros in the specified integer after the lowest one bit.
static int parseInt(String string)
Parses the specified string as a signed decimal integer value.
static int parseInt(String string, int radix)
Parses the specified string as a signed integer value using the specified radix.
static int reverse(int i)
Reverses the order of the bits of the specified integer.
static int reverseBytes(int i)
Reverses the order of the bytes of the specified integer.
static int rotateLeft(int i, int distance)
Rotates the bits of the specified integer to the left by the specified number of bits.
static int rotateRight(int i, int distance)
Rotates the bits of the specified integer to the right by the specified number of bits.
short shortValue()
Returns this object's value as a short.
static int signum(int i)
Returns the value of the signum function for the specified integer.
static String toBinaryString(int i)
Converts the specified integer into its binary string representation.
static String toHexString(int i)
Converts the specified integer into its hexadecimal string representation.
static String toOctalString(int i)
Converts the specified integer into its octal string representation.
String toString()
Returns a string containing a concise, human-readable description of this object.
static String toString(int i)
Converts the specified integer into its decimal string representation.
static String toString(int i, int radix)
Converts the specified signed integer into a string representation based on the specified radix.
static Integer valueOf(String string, int radix)
Parses the specified string as a signed integer value using the specified radix.
static Integer valueOf(int i)
Returns a Integer instance for the specified integer value.
static Integer valueOf(String string)
Parses the specified string as a signed decimal integer value.
[Expand]
Inherited Methods
From class java.lang.Number
From class java.lang.Object
From interface java.lang.Comparable

Constants

public static final int MAX_VALUE

Since: API Level 1

Constant for the maximum int value, 231-1.

Constant Value: 2147483647 (0x7fffffff)

public static final int MIN_VALUE

Since: API Level 1

Constant for the minimum int value, -231.

Constant Value: -2147483648 (0x80000000)

public static final int SIZE

Since: API Level 1

Constant for the number of bits needed to represent an int in two's complement form.

Constant Value: 32 (0x00000020)

public static final Class<Integer> TYPE

Since: API Level 1

The Class object that represents the primitive type int.

Public Constructors

public Integer (int value)

Since: API Level 1

Constructs a new Integer with the specified primitive integer value.

Parameters
value the primitive integer value to store in the new instance.

public Integer (String string)

Since: API Level 1

Constructs a new Integer from the specified string.

Parameters
string the string representation of an integer value.
Throws
NumberFormatException if string can not be decoded into an integer value.
See Also

Public Methods

public static int bitCount (int i)

Since: API Level 1

Counts the number of 1 bits in the specified integer; this is also referred to as population count.

Parameters
i the integer to examine.
Returns
  • the number of 1 bits in i.

public byte byteValue ()

Since: API Level 1

Returns this object's value as a byte. Might involve rounding and/or truncating the value, so it fits into a byte.

Returns
  • the primitive byte value of this object.

public int compareTo (Integer object)

Since: API Level 1

Compares this object to the specified integer object to determine their relative order.

Parameters
object the integer object to compare this object to.
Returns
  • a negative value if the value of this integer is less than the value of object; 0 if the value of this integer and the value of object are equal; a positive value if the value of this integer is greater than the value of object.
See Also

public static Integer decode (String string)

Since: API Level 1

Parses the specified string and returns a Integer instance if the string can be decoded into an integer value. The string may be an optional minus sign "-" followed by a hexadecimal ("0x..." or "#..."), octal ("0..."), or decimal ("...") representation of an integer.

Parameters
string a string representation of an integer value.
Returns
  • an Integer containing the value represented by string.
Throws
NumberFormatException if string can not be parsed as an integer value.

public double doubleValue ()

Since: API Level 1

Returns this object's value as a double. Might involve rounding.

Returns
  • the primitive double value of this object.

public boolean equals (Object o)

Since: API Level 1

Compares this instance with the specified object and indicates if they are equal. In order to be equal, o must be an instance of Integer and have the same integer value as this object.

Parameters
o the object to compare this integer with.
Returns
  • true if the specified object is equal to this Integer; false otherwise.

public float floatValue ()

Since: API Level 1

Returns this object's value as a float. Might involve rounding.

Returns
  • the primitive float value of this object.

public static Integer getInteger (String string, Integer defaultValue)

Since: API Level 1

Returns the Integer value of the system property identified by string. Returns the specified default value if string is null or empty, if the property can not be found or if its value can not be parsed as an integer.

Parameters
string the name of the requested system property.
defaultValue the default value that is returned if there is no integer system property with the requested name.
Returns
  • the requested property's value as an Integer or the default value.

public static Integer getInteger (String string)

Since: API Level 1

Returns the Integer value of the system property identified by string. Returns null if string is null or empty, if the property can not be found or if its value can not be parsed as an integer.

Parameters
string the name of the requested system property.
Returns
  • the requested property's value as an Integer or null.

public static Integer getInteger (String string, int defaultValue)

Since: API Level 1

Returns the Integer value of the system property identified by string. Returns the specified default value if string is null or empty, if the property can not be found or if its value can not be parsed as an integer.

Parameters
string the name of the requested system property.
defaultValue the default value that is returned if there is no integer system property with the requested name.
Returns
  • the requested property's value as an Integer or the default value.

public int hashCode ()

Since: API Level 1

Returns an integer hash code for this object. By contract, any two objects for which equals(Object) returns true must return the same hash code value. This means that subclasses of Object usually override both methods or neither method.

Note that hash values must not change over time unless information used in equals comparisons also changes.

See Writing a correct hashCode method if you intend implementing your own hashCode method.

Returns
  • this object's hash code.

public static int highestOneBit (int i)

Since: API Level 1

Determines the highest (leftmost) bit of the specified integer that is 1 and returns the bit mask value for that bit. This is also referred to as the Most Significant 1 Bit. Returns zero if the specified integer is zero.

Parameters
i the integer to examine.
Returns
  • the bit mask indicating the highest 1 bit in i.

public int intValue ()

Since: API Level 1

Gets the primitive value of this int.

Returns
  • this object's primitive value.

public long longValue ()

Since: API Level 1

Returns this object's value as a long. Might involve rounding and/or truncating the value, so it fits into a long.

Returns
  • the primitive long value of this object.

public static int lowestOneBit (int i)

Since: API Level 1

Determines the lowest (rightmost) bit of the specified integer that is 1 and returns the bit mask value for that bit. This is also referred to as the Least Significant 1 Bit. Returns zero if the specified integer is zero.

Parameters
i the integer to examine.
Returns
  • the bit mask indicating the lowest 1 bit in i.

public static int numberOfLeadingZeros (int i)

Since: API Level 1

Determines the number of leading zeros in the specified integer prior to the highest one bit.

Parameters
i the integer to examine.
Returns
  • the number of leading zeros in i.

public static int numberOfTrailingZeros (int i)

Since: API Level 1

Determines the number of trailing zeros in the specified integer after the lowest one bit.

Parameters
i the integer to examine.
Returns
  • the number of trailing zeros in i.

public static int parseInt (String string)

Since: API Level 1

Parses the specified string as a signed decimal integer value. The ASCII character - ('-') is recognized as the minus sign.

Parameters
string the string representation of an integer value.
Returns
  • the primitive integer value represented by string.
Throws
NumberFormatException if string is null, has a length of zero or can not be parsed as an integer value.

public static int parseInt (String string, int radix)

Since: API Level 1

Parses the specified string as a signed integer value using the specified radix. The ASCII character - ('-') is recognized as the minus sign.

Parameters
string the string representation of an integer value.
radix the radix to use when parsing.
Returns
  • the primitive integer value represented by string using radix.
Throws
NumberFormatException if string is null or has a length of zero, radix < Character.MIN_RADIX, radix > Character.MAX_RADIX, or if string can not be parsed as an integer value.

public static int reverse (int i)

Since: API Level 1

Reverses the order of the bits of the specified integer.

Parameters
i the integer value for which to reverse the bit order.
Returns
  • the reversed value.

public static int reverseBytes (int i)

Since: API Level 1

Reverses the order of the bytes of the specified integer.

Parameters
i the integer value for which to reverse the byte order.
Returns
  • the reversed value.

public static int rotateLeft (int i, int distance)

Since: API Level 1

Rotates the bits of the specified integer to the left by the specified number of bits.

Parameters
i the integer value to rotate left.
distance the number of bits to rotate.
Returns
  • the rotated value.

public static int rotateRight (int i, int distance)

Since: API Level 1

Rotates the bits of the specified integer to the right by the specified number of bits.

Parameters
i the integer value to rotate right.
distance the number of bits to rotate.
Returns
  • the rotated value.

public short shortValue ()

Since: API Level 1

Returns this object's value as a short. Might involve rounding and/or truncating the value, so it fits into a short.

Returns
  • the primitive short value of this object.

public static int signum (int i)

Since: API Level 1

Returns the value of the signum function for the specified integer.

Parameters
i the integer value to check.
Returns
  • -1 if i is negative, 1 if i is positive, 0 if i is zero.

public static String toBinaryString (int i)

Since: API Level 1

Converts the specified integer into its binary string representation. The returned string is a concatenation of '0' and '1' characters.

Parameters
i the integer to convert.
Returns
  • the binary string representation of i.

public static String toHexString (int i)

Since: API Level 1

Converts the specified integer into its hexadecimal string representation. The returned string is a concatenation of characters from '0' to '9' and 'a' to 'f'.

Parameters
i the integer to convert.
Returns
  • the hexadecimal string representation of i.

public static String toOctalString (int i)

Since: API Level 1

Converts the specified integer into its octal string representation. The returned string is a concatenation of characters from '0' to '7'.

Parameters
i the integer to convert.
Returns
  • the octal string representation of i.

public String toString ()

Since: API Level 1

Returns a string containing a concise, human-readable description of this object. Subclasses are encouraged to override this method and provide an implementation that takes into account the object's type and data. The default implementation is equivalent to the following expression: 

   getClass().getName() + '@' + Integer.toHexString(hashCode())

See Writing a useful toString method if you intend implementing your own toString method.

Returns
  • a printable representation of this object.

public static String toString (int i)

Since: API Level 1

Converts the specified integer into its decimal string representation. The returned string is a concatenation of a minus sign if the number is negative and characters from '0' to '9'.

Parameters
i the integer to convert.
Returns
  • the decimal string representation of i.

public static String toString (int i, int radix)

Since: API Level 1

Converts the specified signed integer into a string representation based on the specified radix. The returned string is a concatenation of a minus sign if the number is negative and characters from '0' to '9' and 'a' to 'z', depending on the radix. If radix is not in the interval defined by Character.MIN_RADIX and Character.MAX_RADIX then 10 is used as the base for the conversion.

This method treats its argument as signed. If you want to convert an unsigned value to one of the common non-decimal bases, you may find toBinaryString(int), #toHexString, or toOctalString(int) more convenient.

Parameters
i the signed integer to convert.
radix the base to use for the conversion.
Returns
  • the string representation of i.

public static Integer valueOf (String string, int radix)

Since: API Level 1

Parses the specified string as a signed integer value using the specified radix.

Parameters
string the string representation of an integer value.
radix the radix to use when parsing.
Returns
  • an Integer instance containing the integer value represented by string using radix.
Throws
NumberFormatException if string is null or has a length of zero, radix < Character.MIN_RADIX, radix > Character.MAX_RADIX, or if string can not be parsed as an integer value.
See Also

public static Integer valueOf (int i)

Since: API Level 1

Returns a Integer instance for the specified integer value.

If it is not necessary to get a new Integer instance, it is recommended to use this method instead of the constructor, since it maintains a cache of instances which may result in better performance.

Parameters
i the integer value to store in the instance.
Returns
  • a Integer instance containing i.

public static Integer valueOf (String string)

Since: API Level 1

Parses the specified string as a signed decimal integer value.

Parameters
string the string representation of an integer value.
Returns
  • an Integer instance containing the integer value represented by string.
Throws
NumberFormatException if string is null, has a length of zero or can not be parsed as an integer value.
See Also