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_VALUEA constant holding the maximum value an  intcan
 have, 231-1. | 
| static int | MIN_VALUEA constant holding the minimum value an  intcan
 have, -231. | 
| static int | SIZEThe number of bits used to represent an  intvalue in two's
 complement binary form. | 
| static Class<Integer> | TYPEThe  Classinstance representing the primitive typeint. | 
| Constructor and Description | 
|---|
| Integer(int value)Constructs a newly allocated  Integerobject that
 represents the specifiedintvalue. | 
| Integer(String s)Constructs a newly allocated  Integerobject that
 represents theintvalue indicated by theStringparameter. | 
| Modifier and Type | Method and Description | 
|---|---|
| static int | bitCount(int i)Returns the number of one-bits in the two's complement binary
 representation of the specified  intvalue. | 
| byte | byteValue()Returns the value of this  Integeras abyte. | 
| static int | compare(int x,
       int y)Compares two  intvalues numerically. | 
| int | compareTo(Integer anotherInteger)Compares two  Integerobjects numerically. | 
| static Integer | decode(String nm)Decodes a  Stringinto anInteger. | 
| double | doubleValue()Returns the value of this  Integeras adouble. | 
| boolean | equals(Object obj)Compares this object to the specified object. | 
| float | floatValue()Returns the value of this  Integeras afloat. | 
| 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  intvalue with at most a single one-bit, in the
 position of the highest-order ("leftmost") one-bit in the specifiedintvalue. | 
| int | intValue()Returns the value of this  Integeras anint. | 
| long | longValue()Returns the value of this  Integeras along. | 
| static int | lowestOneBit(int i)Returns an  intvalue with at most a single one-bit, in the
 position of the lowest-order ("rightmost") one-bit in the specifiedintvalue. | 
| 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  intvalue. | 
| 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
  intvalue. | 
| 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  intvalue. | 
| 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  intvalue. | 
| static int | rotateLeft(int i,
          int distance)Returns the value obtained by rotating the two's complement binary
 representation of the specified  intvalue 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  intvalue right by the
 specified number of bits. | 
| short | shortValue()Returns the value of this  Integeras ashort. | 
| static int | signum(int i)Returns the signum function of the specified  intvalue. | 
| 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  Stringobject representing thisInteger's value. | 
| static String | toString(int i)Returns a  Stringobject 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  Integerinstance representing the specifiedintvalue. | 
| static Integer | valueOf(String s)Returns an  Integerobject holding the
 value of the specifiedString. | 
| static Integer | valueOf(String s,
       int radix)Returns an  Integerobject holding the value
 extracted from the specifiedStringwhen parsed
 with the radix given by the second argument. | 
public static final int MIN_VALUE
int can
 have, -231.public static final int MAX_VALUE
int can
 have, 231-1.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 radix-N 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_RADIXpublic static String toHexString(int i)
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 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 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'.i - an integer to be converted to a string.public static String toBinaryString(int i)
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.
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 sInteger 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 Numbershort.public int intValue()
Integer as an
 int.public long longValue()
Integer as a
 long.public float floatValue()
Integer as a
 float.floatValue in class Numberfloat.public double doubleValue()
Integer as a
 double.doubleValue in class Numberdouble.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 Objectint 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 Objectobj - the object to compare with.true if the objects are the same;
          false otherwise.Object.hashCode(), 
HashMappublic 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:
- Signopt DecimalNumeral
- Signopt
0xHexDigits- Signopt
0XHexDigits- Signopt
#HexDigits- Signopt
0OctalDigits
- 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 nmNumberFormatException - 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 > ypublic static int highestOneBit(int i)
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.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.public static int lowestOneBit(int i)
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.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.public static int numberOfLeadingZeros(int i)
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:
 
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
 one-bits 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
 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).
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
 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).
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, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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