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JDK 5 Documentation v1.1.8, Java 2 SDK 英文文档
Class java.lang.Integer  JDK 5 Documentation v1.1.8, Java 2 SDK 英文文档
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Class java.lang.Integer
java.lang.Object

+java.lang.Number

+java.lang.Integer
 public final class Integer
 extends Number
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
.

MAX_VALUE
 The largest value of type
int
.

MIN_VALUE
 The smallest value of type
int
.

TYPE
 The Class object representing the primitive type int.

Integer(int)
 Constructs a newly allocated
Integer
object that
represents the primitive int
argument.

Integer(String)
 Constructs a newly allocated
Integer
object that
represents the value represented by the string.

byteValue()
 Returns the value of this Integer as a byte.

decode(String)
 Decodes a string into an Integer.

doubleValue()
 Returns the value of this Integer as a double.

equals(Object)
 Compares this object to the specified object.

floatValue()
 Returns the value of this Integer as a float.

getInteger(String)
 Determines the integer value of the system property with the
specified name.

getInteger(String, int)
 Determines the integer value of the system property with the
specified name.

getInteger(String, Integer)
 Determines the integer value of the system property with the
specified name.

hashCode()
 Returns a hashcode for this Integer.

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

longValue()
 Returns the value of this Integer as a long.

parseInt(String)
 Parses the string argument as a signed decimal integer.

parseInt(String, int)
 Parses the string argument as a signed integer in the radix
specified by the second argument.

shortValue()
 Returns the value of this Integer as a short.

toBinaryString(int)
 Creates a string representation of the integer argument as an
unsigned integer in base 2.

toHexString(int)
 Creates a string representation of the integer argument as an
unsigned integer in base 16.

toOctalString(int)
 Creates a string representation of the integer argument as an
unsigned integer in base 8.

toString()
 Returns a String object representing this Integer's value.

toString(int)
 Returns a new String object representing the specified integer.

toString(int, int)
 Creates a string representation of the first argument in the
radix specified by the second argument.

valueOf(String)
 Returns a new Integer object initialized to the value of the
specified String.

valueOf(String, int)
 Returns a new Integer object initialized to the value of the
specified String.
MIN_VALUE
public static final int MIN_VALUE
 The smallest value of type
int
.
MAX_VALUE
public static final int MAX_VALUE
 The largest value of type
int
.
TYPE
public static final Class TYPE
 The Class object representing the primitive type int.
Integer
public Integer(int value)
 Constructs a newly allocated
Integer
object that
represents the primitive int
argument.
 Parameters:
 value  the value to be represented by the
Integer
.
Integer
public Integer(String s) throws NumberFormatException
 Constructs a newly allocated
Integer
object that
represents the value represented by the string. The string is
converted to an int value as if by the valueOf
method.
 Parameters:
 s  the
String
to be converted to an
Integer
.
 Throws: NumberFormatException
 if the
String
does not
contain a parsable integer.
 See Also:
 valueOf
toString
public static String toString(int i,
int radix)
 Creates 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 ''
. If the first
argument is not negative, no sign character appears in the result.
The following ASCII characters are used as digits:
0123456789abcdefghijklmnopqrstuvwxyz
 Parameters:
 i  an integer.
 radix  the radix.
 Returns:
 a string representation of the argument in the specified radix.
 See Also:
 MAX_RADIX, MIN_RADIX
toHexString
public static String toHexString(int i)
 Creates a string representation of the integer argument as an
unsigned integer in base 16.
The unsigned integer value is the argument plus 2^{32} if
the argument is negative; otherwise, it is equal to the argument.
This value is converted to a string of ASCII digits in hexadecimal
(base 16) with no extra leading 0
s.
 Parameters:
 i  an integer.
 Returns:
 the string representation of the unsigned integer value
represented by the argument in hexadecimal (base 16).
toOctalString
public static String toOctalString(int i)
 Creates a string representation of the integer argument as an
unsigned integer in base 8.
The unsigned integer value is the argument plus 2^{32} if
the argument is negative; otherwise, it is equal to the argument.
This value is converted to a string of ASCII digits in octal
(base 8) with no extra leading 0
s.
 Parameters:
 i  an integer
 Returns:
 the string representation of the unsigned integer value
represented by the argument in octal (base&mnsp;8).
toBinaryString
public static String toBinaryString(int i)
 Creates a string representation of the integer argument as an
unsigned integer in base 2.
The unsigned integer value is the argument plus 2^{32}if
the argument is negative; otherwise it is equal to the argument.
This value is converted to a string of ASCII digits in binary
(base 2) with no extra leading 0
s.
 Parameters:
 i  an integer.
 Returns:
 the string representation of the unsigned integer value
represented by the argument in binary (base 2).
toString
public static String toString(int i)
 Returns a new String object representing the specified integer. The radix
is assumed to be 10.
 Parameters:
 i  an integer to be converted.
 Returns:
 a string representation of the argument in base 10.
parseInt
public static int parseInt(String s,
int radix) throws NumberFormatException
 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
Character.digit
returns a
nonnegative value), except that the first character may be an
ASCII minus sign ''
to indicate a negative value.
The resulting integer value is returned.
 Parameters:
 s  the
String
containing the integer.
 radix  the radix to be used.
 Returns:
 the integer represented by the string argument in the
specified radix.
 Throws: NumberFormatException
 if the string does not contain a
parsable integer.
parseInt
public static int parseInt(String s) throws NumberFormatException
 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
''
to
indicate a negative value.
 Parameters:
 s  a string.
 Returns:
 the integer represented by the argument in decimal.
 Throws: NumberFormatException
 if the string does not contain a
parsable integer.
valueOf
public static Integer valueOf(String s,
int radix) throws NumberFormatException
 Returns a new Integer object initialized to the value of the
specified String. Throws an exception if the String cannot be
parsed as an int.
 Parameters:
 s  the string to be parsed.
 Returns:
 a newly constructed
Integer
initialized to the
value represented by the string argument in the specified
radix.
 Throws: NumberFormatException
 if the
String
does not
contain a parsable integer.
valueOf
public static Integer valueOf(String s) throws NumberFormatException
 Returns a new Integer object initialized to the value of the
specified String. Throws an exception if the String cannot be
parsed as an int. The radix is assumed to be 10.
 Parameters:
 s  the string to be parsed.
 Returns:
 a newly constructed
Integer
initialized to the
value represented by the string argument.
 Throws: NumberFormatException
 if the string does not contain a
parsable integer.
byteValue
public byte byteValue()
 Returns the value of this Integer as a byte.
 Overrides:
 byteValue in class Number
shortValue
public short shortValue()
 Returns the value of this Integer as a short.
 Overrides:
 shortValue in class Number
intValue
public int intValue()
 Returns the value of this Integer as an int.
 Returns:
 the
int
value represented by this object.
 Overrides:
 intValue in class Number
longValue
public long longValue()
 Returns the value of this Integer as a long.
 Returns:
 the
int
value represented by this object that is
converted to type long
and the result of the
conversion is returned.
 Overrides:
 longValue in class Number
floatValue
public float floatValue()
 Returns the value of this Integer as a float.
 Returns:
 the
int
value represented by this object is
converted to type float
and the result of the
conversion is returned.
 Overrides:
 floatValue in class Number
doubleValue
public double doubleValue()
 Returns the value of this Integer as a double.
 Returns:
 the
int
value represented by this object is
converted to type double
and the result of the
conversion is returned.
 Overrides:
 doubleValue in class Number
toString
public String toString()
 Returns a String object representing this Integer's value.
 Returns:
 a string representation of the value of this object in
base 10.
 Overrides:
 toString in class Object
hashCode
public int hashCode()
 Returns a hashcode for this Integer.
 Returns:
 a hash code value for this object.
 Overrides:
 hashCode in class Object
equals
public 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  the object to compare with.
 Returns:

true
if the objects are the same;
false
otherwise.
 Overrides:
 equals in class Object
getInteger
public static 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 getProperty
and , a method defined by the System
class. 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, or if the
property does not have the correct numeric format, then
null
is returned.
 Parameters:
 nm  property name.
 Returns:
 the
Integer
value of the property.
 See Also:
 getProperty, getProperty
getInteger
public static 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 getProperty
and , a method defined by the System
class. 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, or if the
property does not have the correct numeric format, then an
Integer
object that represents the value of the
second argument is returned.
 Parameters:
 nm  property name.
 val  default value.
 Returns:
 the
Integer
value of the property.
 See Also:
 getProperty, getProperty
getInteger
public static Integer getInteger(String nm,
Integer 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 getProperty
and , a method defined by the System
class. The
string value of this property is then interpreted as an integer
value and an Integer
object representing this value is
returned.
If the property value begins with "0x
" or
"#
", not followed by a minus sign, the rest
of it is parsed as a hexadecimal integer exactly as for the method
Integer.valueOf
with radix 16.
If the property value begins with "0
" then
it is parsed as an octal integer exactly as for the method
Integer.valueOf
with radix 8.
Otherwise the property value is parsed as a decimal integer
exactly as for the method Integer.valueOf
with radix 10.
The second argument is the default value. If there is no property
of the specified name, or if the property does not have the
correct numeric format, then the second argument is returned.
 Parameters:
 nm  property name.
 val  default value.
 Returns:
 the
Integer
value of the property.
 See Also:
 getProperty, getProperty
decode
public static Integer decode(String nm) throws NumberFormatException
 Decodes a string into an Integer. Deals with decimal, hexadecimal,
and octal numbers.
 Parameters:
 nm  the string to decode
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