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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).
Integer
object that
represents the
int
value indicated by the
String
parameter.
double
doubleValue
()
Integer
as a
double
after a widening primitive conversion.
boolean
equals
(
Object
obj)
float
floatValue
()
Integer
as a
float
after a widening primitive conversion.
static
Integer
getInteger
(
String
nm)
static
Integer
getInteger
(
String
nm,
int val)
static
Integer
getInteger
(
String
nm,
Integer
val)
hashCode
()
Integer
.
static int
hashCode
(int value)
int
value; compatible with
Integer.hashCode()
.
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.
intValue
()
Integer
as an
int
.
longValue
()
Integer
as a
long
after a widening primitive conversion.
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.
static int
max
(int a,
int b)
int
values
as if by calling
Math.max
.
static int
min
(int a,
int b)
int
values
as if by calling
Math.min
.
static int
numberOfLeadingZeros
(int i)
int
value.
static int
numberOfTrailingZeros
(int i)
int
value.
static int
parseInt
(
String
s)
static int
parseInt
(
String
s,
int radix)
static int
parseUnsignedInt
(
String
s)
static int
parseUnsignedInt
(
String
s,
int radix)
static int
remainderUnsigned
(int dividend,
int divisor)
static int
reverse
(int i)
int
value.
static int
reverseBytes
(int i)
int
value.
static int
rotateLeft
(int i,
int distance)
int
value left by the
specified number of bits.
static int
rotateRight
(int i,
int distance)
int
value right by the
specified number of bits.
short
shortValue
()
Integer
as a
short
after a narrowing primitive conversion.
static int
signum
(int i)
int
value.
static int
sum
(int a,
int b)
static
String
toBinaryString
(int i)
static
String
toHexString
(int i)
static
String
toOctalString
(int i)
String
toString
()
String
object representing this
Integer
's value.
static
String
toString
(int i)
String
object representing the
specified integer.
static
String
toString
(int i,
int radix)
static long
toUnsignedLong
(int x)
long
by an unsigned
conversion.
static
String
toUnsignedString
(int i)
static
String
toUnsignedString
(int i,
int radix)
static
Integer
valueOf
(int i)
Integer
instance representing the specified
int
value.
static
Integer
valueOf
(
String
s)
Integer
object holding the
value of the specified
String
.
static
Integer
valueOf
(
String
s,
int radix)
Integer
object holding the value
extracted from the specified
String
when parsed
with the radix given by the second argument.
int
can
have, -2
31
.
int
can
have, 2
31
-1.
public static final Class<Integer> TYPE
Class
instance representing the primitive type
int
.
@Native public static final int SIZE
int
value in two's
complement binary form.
public static final int BYTES
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_RADIX
public static String toUnsignedString(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.
Note that since the first argument is treated as an unsigned value, no leading sign character is printed.
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 behavior of radixes and the characters used as digits
are the same as
toString
.
i
- an integer to be converted to an unsigned string.
radix
- the radix to use in the string representation.
toString(int, int)
public static String toHexString(int i)
The unsigned integer value is the argument plus 2 32 if the argument is negative; otherwise, it is equal to the argument. This value is converted to a string of ASCII digits in hexadecimal (base 16) with no extra leading
The value of the argument can be recovered from the returned
string
s
by calling
Integer.parseUnsignedInt(s, 16)
.
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.
parseUnsignedInt(String, int)
,
toUnsignedString(int, int)
public static String toOctalString(int i)
The unsigned integer value is the argument plus 2
32
if the argument is negative; otherwise, it is equal to the
argument. This value is converted to a string of ASCII digits
in octal (base 8) with no extra leading
0
s.
The value of the argument can be recovered from the returned
string
s
by calling
Integer.parseUnsignedInt(s, 8)
.
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.
parseUnsignedInt(String, int)
,
toUnsignedString(int, int)
public static String toBinaryString(int i)
The unsigned integer value is the argument plus 2
32
if the argument is negative; otherwise it is equal to the
argument. This value is converted to a string of ASCII digits
in binary (base 2) with no extra leading
0
s.
The value of the argument can be recovered from the returned
string
s
by calling
Integer.parseUnsignedInt(s, 2)
.
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.
parseUnsignedInt(String, int)
,
toUnsignedString(int, int)
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 String toUnsignedString(int i)
toUnsignedString(int,
int)
method.
i
- an integer to be converted to an unsigned string.
toUnsignedString(int, int)
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 parsed
radix
- 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 parsed
NumberFormatException
- if the string does not contain a
parsable integer.
MAX_VALUE
.
The characters in the string must all be digits of the
specified radix (as determined by whether
Character.digit(char, int)
returns a nonnegative
value), except that the first character may be an ASCII plus
sign
'+'
(
'\u002B'
). 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
.
'+'
(
'\u002B'
) provided that the
string is longer than length 1.
int
, 2
32
-1.
s
- the
String
containing the unsigned integer
representation to be parsed
radix
- the radix to be used while parsing
s
.
NumberFormatException
- if the
String
does not contain a parsable
int
.
public static int parseUnsignedInt(String s) throws NumberFormatException
'+'
(
'\u002B'
). The resulting integer value
is returned, exactly as if the argument and the radix 10 were
given as arguments to the
parseUnsignedInt(java.lang.String, int)
method.
s
- a
String
containing the unsigned
int
representation to be parsed
NumberFormatException
- if the string does not contain a
parsable unsigned integer.
Integer
object holding the value
extracted from the specified
String
when parsed
with the radix given by the second argument. The first argument
is interpreted as representing a signed integer in the radix
specified by the second argument, exactly as if the arguments
were given to the
parseInt(java.lang.String, int)
method. The result is an
Integer
object that
represents the integer value specified by the string.
In other words, this method returns an
Integer
object equal to the value of:
new Integer(Integer.parseInt(s, radix))
s
- the string to be parsed.
radix
- the radix to be used in interpreting
s
Integer
object holding the value
represented by the string argument in the specified
radix.
NumberFormatException
- if the
String
does not contain a parsable
int
.
public static Integer valueOf(String s) throws NumberFormatException
Integer
object holding the
value of the specified
String
. The argument is
interpreted as representing a signed decimal integer, exactly
as if the argument were given to the
parseInt(java.lang.String)
method. The result is an
Integer
object that represents the integer value
specified by the string.
In other words, this method returns an
Integer
object equal to the value of:
new Integer(Integer.parseInt(s))
s
- the string to be parsed.
Integer
object holding the value
represented by the string argument.
NumberFormatException
- if the string cannot be parsed
as an integer.
public static Integer valueOf(int i)
Integer
instance representing the specified
int
value. If a new
Integer
instance is not
required, this method should generally be used in preference to
the constructor
Integer(int)
, as this method is likely
to yield significantly better space and time performance by
caching frequently requested values.
This method will always cache values in the range -128 to 127,
inclusive, and may cache other values outside of this range.
i
- an
int
value.
Integer
instance representing
i
.
public byte byteValue()
Integer
as a
byte
after a narrowing primitive conversion.
byteValue
in class
Number
byte
.
public short shortValue()
Integer
as a
short
after a narrowing primitive conversion.
shortValue
in class
Number
short
.
intValue
in class
Number
int
.
public long longValue()
Integer
as a
long
after a widening primitive conversion.
longValue
in class
Number
long
.
toUnsignedLong(int)
public float floatValue()
Integer
as a
float
after a widening primitive conversion.
floatValue
in class
Number
float
.
public double doubleValue()
Integer
as a
double
after a widening primitive conversion.
doubleValue
in class
Number
double
.
public String toString()
String
object representing this
Integer
's value. The value is converted to signed
decimal representation and returned as a string, exactly as if
the integer value were given as an argument to the
toString(int)
method.
toString
in class
Object
int
value represented by this
Integer
object.
Object.equals(java.lang.Object)
,
System.identityHashCode(java.lang.Object)
public static int hashCode(int value)
int
value; compatible with
Integer.hashCode()
.
value
- the value to hash
int
value.
public boolean equals(Object obj)
true
if and only if the argument is not
null
and is an
Integer
object that
contains the same
int
value as this object.
equals
in class
Object
obj
- the object to compare with.
true
if the objects are the same;
false
otherwise.
Object.hashCode()
,
HashMap
public static Integer getInteger(String nm)
The first argument is treated as the name of a system
property. System properties are accessible through the
System.getProperty(java.lang.String)
method. The
string value of this property is then interpreted as an integer
value using the grammar supported by
decode
and
an
Integer
object representing this value is returned.
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.
SecurityException
- for the same reasons as
System.getProperty
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 using the grammar supported by
decode
and
an
Integer
object representing this value is returned.
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.
nm
- property name.
val
- default value.
Integer
value of the property.
SecurityException
- for the same reasons as
System.getProperty
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
decode
method,
and an
Integer
object representing this value is
returned; in summary:
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.
SecurityException
- for the same reasons as
System.getProperty
System.getProperty(java.lang.String)
,
System.getProperty(java.lang.String, 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:
0x
HexDigits
0X
HexDigits
#
HexDigits
0
OctalDigits
The sequence of characters following an optional
sign and/or radix specifier ("
0x
", "
0X
",
"
#
", or leading zero) is parsed as by the
Integer.parseInt
method with the indicated radix (10, 16, or
8). This sequence of characters must represent a positive
value or a
NumberFormatException
will be thrown. The
result is negated if first character of the specified
String
is the minus sign. No whitespace characters are
permitted in the
String
.
nm
- the
String
to decode.
Integer
object holding the
int
value represented by
nm
NumberFormatException
- if the
String
does not
contain a parsable integer.
parseInt(java.lang.String, int)
public int compareTo(Integer anotherInteger)
Integer
objects numerically.
compareTo
in interface
Comparable
<
Integer
>
anotherInteger
- the
Integer
to be compared.
0
if this
Integer
is
equal to the argument
Integer
; a value less than
0
if this
Integer
is numerically less
than the argument
Integer
; and a value greater
than
0
if this
Integer
is numerically
greater than the argument
Integer
(signed
comparison).
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 compare
y
- the second
int
to compare
0
if
x == y
;
a value less than
0
if
x < y
; and
a value greater than
0
if
x > y
public static int compareUnsigned(int x, int y)
int
values numerically treating the values
as unsigned.
x
- the first
int
to compare
y
- the second
int
to compare
0
if
x == y
; a value less
than
0
if
x < y
as unsigned values; and
a value greater than
0
if
x > y
as
unsigned values
public static long toUnsignedLong(int x)
long
by an unsigned
conversion. In an unsigned conversion to a
long
, the
high-order 32 bits of the
long
are zero and the
low-order 32 bits are equal to the bits of the integer
argument.
Consequently, zero and positive
int
values are mapped
to a numerically equal
long
value and negative
int
values are mapped to a
long
value equal to the
input plus 2
32
.
x
- the value to convert to an unsigned
long
long
by an unsigned
conversion
public static int divideUnsigned(int dividend, int divisor)
Note that in two's complement arithmetic, the three other
basic arithmetic operations of add, subtract, and multiply are
bit-wise identical if the two operands are regarded as both
being signed or both being unsigned. Therefore separate
addUnsigned
, etc. methods are not provided.
dividend
- the value to be divided
divisor
- the value doing the dividing
remainderUnsigned(int, int)
public static int remainderUnsigned(int dividend, int divisor)
dividend
- the value to be divided
divisor
- the value doing the dividing
divideUnsigned(int, int)
public 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.
i
- the value whose highest one bit is to be computed
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.
i
- the value whose lowest one bit is to be computed
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)
i
- the value whose number of leading zeros is to be computed
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.
i
- the value whose number of trailing zeros is to be computed
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
.
i
- the value whose bits are to be counted
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)
.
i
- the value whose bits are to be rotated left
distance
- the number of bit positions to rotate left
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)
.
i
- the value whose bits are to be rotated right
distance
- the number of bit positions to rotate right
int
value right by the
specified number of bits.
public static int reverse(int i)
int
value.
i
- the value to be reversed
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.)
i
- the value whose signum is to be computed
int
value.
public static int reverseBytes(int i)
int
value.
i
- the value whose bytes are to be reversed
int
value.
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千杯不醉的拖把 · MySQL函数、存储过程、索引学习 - LoremMoon 20 小时前 |