home | O'Reilly's CD bookshelfs | FreeBSD | Linux | Cisco | Cisco Exam    

Java Language Reference

Previous Chapter 10
The java.lang Package
Next
 

Number

Name

Number

Synopsis

Class Name:

java.lang.Number

Superclass:

java.lang.Object

Immediate Subclasses:

java.lang.Byte, java.lang.Double,

java.lang.Float, java.lang.Integer,

java.lang.Long, java.lang.Short,

java.math.BigDecimal,

java.math.BigInteger

Interfaces Implemented:

java.io.Serializable

Availability:

JDK 1.0 or later

Description

The Number class is an abstract class that serves as the superclass for all of the classes that provide object wrappers for primitive numeric values: byte, short, int, long, float, and double. Wrapping a primitive value is useful when you need to treat such a value as an object. For example, there are a number of utility methods that take a reference to an Object as one of their arguments. You cannot specify a primitive value for one of these arguments, but you can provide a reference to an object that encapsulates the primitive value. Furthermore, as of JDK 1.1, these wrapper classes are necessary to support the Reflection API and class literals.

The Number class defines six methods that must be implemented by its subclasses: byteValue(), shortValue(), intValue(), longValue(), floatValue(), and doubleValue(). This means that a Number object can be fetched as an byte, short, int, long, float, or double value, without regard for its actual class.

Class Summary

public abstract class java.lang.Number extends java.lang.Number
                                       implements java.io.Serializable {
    // Instance Methods
    public abstract byte byteValue();                  // New in 1.1
    public abstract double doubleValue();
    public abstract float floatValue();
    public abstract int intValue();
    public abstract long longValue();
    public abstract short shortValue();                // New in 1.1
}

Instance Methods

byteValue

public abstract byte byteValue()

Availability

New as of JDK 1.1

Returns

The value of this object as a byte.

Description

This method returns the value of this object as a byte. If the data type of the value is not byte, rounding may occur.

doubleValue

public abstract double doubleValue()

Returns

The value of this object as a double.

Description

This method returns the value of this object as a double. If the data type of the value is not double, rounding may occur.

floatValue

public abstract float floatValue()

Returns

The value of this object as a float.

Description

This method returns the value of this object as a float. If the data type of the value is not float, rounding may occur.

intValue

public abstract int intValue()

Returns

The value of this object as an int.

Description

This method returns the value of this object as an int. If the type of value is not an int, rounding may occur.

longValue

public abstract long longValue()

Returns

The value of this object as a long.

Description

This method returns the value of this object as a long. If the type of value is not a long, rounding may occur.

shortValue

public abstract short shortValue()

Availability

New as of JDK 1.1

Returns

The value of this object as a short.

Description

This method returns the value of this object as a short. If the type of value is not a short, rounding may occur.

Inherited Methods

Method

Inherited From

Method

Inherited From

clone()

Object

equals(Object)

Object

finalize()

Object

getClass()

Object

hashCode()

Object

notify()

Object

notifyAll()

Object

toString()

Object

wait()

Object

wait(long)

Object

wait(long, int)

Object

   


Previous Home Next
Math Book Index Object

Java in a Nutshell Java Language Reference Java AWT Java Fundamental Classes Exploring Java










??????????????@Mail.ru