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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.

Variable Index

o MAX_VALUE
The largest value of type int.
o MIN_VALUE
The smallest value of type int.
o TYPE
The Class object representing the primitive type int.

Constructor Index

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

Method Index

o byteValue()
Returns the value of this Integer as a byte.
o decode(String)
Decodes a string into an Integer.
o doubleValue()
Returns the value of this Integer as a double.
o equals(Object)
Compares this object to the specified object.
o floatValue()
Returns the value of this Integer as a float.
o getInteger(String)
Determines the integer value of the system property with the specified name.
o getInteger(String, int)
Determines the integer value of the system property with the specified name.
o getInteger(String, Integer)
Determines the integer value of the system property with the specified name.
o hashCode()
Returns a hashcode for this Integer.
o intValue()
Returns the value of this Integer as an int.
o longValue()
Returns the value of this Integer as a long.
o parseInt(String)
Parses the string argument as a signed decimal integer.
o parseInt(String, int)
Parses the string argument as a signed integer in the radix specified by the second argument.
o shortValue()
Returns the value of this Integer as a short.
o toBinaryString(int)
Creates a string representation of the integer argument as an unsigned integer in base 2.
o toHexString(int)
Creates a string representation of the integer argument as an unsigned integer in base 16.
o toOctalString(int)
Creates a string representation of the integer argument as an unsigned integer in base 8.
o toString()
Returns a String object representing this Integer's value.
o toString(int)
Returns a new String object representing the specified integer.
o toString(int, int)
Creates a string representation of the first argument in the radix specified by the second argument.
o valueOf(String)
Returns a new Integer object initialized to the value of the specified String.
o valueOf(String, int)
Returns a new Integer object initialized to the value of the specified String.

Variables

o MIN_VALUE 
 public static final int MIN_VALUE
The smallest value of type int.

o MAX_VALUE 
 public static final int MAX_VALUE
The largest value of type int.

o TYPE 
 public static final Class TYPE
The Class object representing the primitive type int.

Constructors

o 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.
o 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

Methods

o 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
o 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 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.

Parameters:
i - an integer.
Returns:
the string representation of the unsigned integer value represented by the argument in hexadecimal (base 16).
o 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 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.

Parameters:
i - an integer
Returns:
the string representation of the unsigned integer value represented by the argument in octal (base&mnsp;8).
o 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 232if 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.

Parameters:
i - an integer.
Returns:
the string representation of the unsigned integer value represented by the argument in binary (base 2).
o 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.
o 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.
o 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.
o 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.
o 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.
o byteValue 
 public byte byteValue()
Returns the value of this Integer as a byte.

Overrides:
byteValue in class Number
o shortValue 
 public short shortValue()
Returns the value of this Integer as a short.

Overrides:
shortValue in class Number
o 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
o 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
o 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
o 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
o 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
o hashCode 
 public int hashCode()
Returns a hashcode for this Integer.

Returns:
a hash code value for this object.
Overrides:
hashCode in class Object
o 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
o 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
o 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
o 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
o 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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