java.net
Class NetworkInterface

java.lang.Object
  java.net.NetworkInterface

public final class NetworkInterface

extends Object

This class represents a Network Interface made up of a name, and a list of IP addresses assigned to this interface. It is used to identify the local interface on which a multicast group is joined. Interfaces are normally known by names such as "le0".

Since:

1.4

Field Summary

private InetAddress[]	addrs
private String	displayName
private int	index
private String	name

Constructor Summary

(package private)	NetworkInterface() Returns an NetworkInterface object with index set to 0 and name to null.
(package private)	NetworkInterface(String name, int index, InetAddress[] addrs)

Method Summary

boolean	equals(Object obj) Compares this object against the specified object.
private static NetworkInterface[]	getAll()
(package private) static NetworkInterface	getByIndex(int index) Get a network interface given its index.
static NetworkInterface	getByInetAddress(InetAddress addr) Convenience method to search for a network interface that has the specified Internet Protocol (IP) address bound to it.
private static NetworkInterface	getByInetAddress0(InetAddress addr)
static NetworkInterface	getByName(String name) Searches for the network interface with the specified name.
private static NetworkInterface	getByName0(String name)
String	getDisplayName() Get the display name of this network interface.
(package private) int	getIndex() Get the index of this network interface.
Enumeration	getInetAddresses() Convenience method to return an Enumeration with all or a subset of the InetAddresses bound to this network interface.
String	getName() Get the name of this network interface.
static Enumeration	getNetworkInterfaces() Returns all the interfaces on this machine.
int	hashCode() Returns a hash code value for the object.
private static void	init()
String	toString() Returns a string representation of the object.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

name

private String name

displayName

private String displayName

index

private int index

addrs

private InetAddress[] addrs

Constructor Detail

NetworkInterface

NetworkInterface()

Returns an NetworkInterface object with index set to 0 and name to null. Setting such an interface on a MulticastSocket will cause the kernel to choose one interface for sending multicast packets.

NetworkInterface

NetworkInterface(String name,
                 int index,
                 InetAddress[] addrs)

Method Detail

getName

public String getName()

Get the name of this network interface.

Returns:

the name of this network interface

getInetAddresses

public Enumeration getInetAddresses()

Convenience method to return an Enumeration with all or a subset of the InetAddresses bound to this network interface.

If there is a security manager, its checkConnect method is called for each InetAddress. Only InetAddresses where the checkConnect doesn't throw a SecurityException will be returned in the Enumeration.

Returns:

an Enumeration object with all or a subset of the InetAddresses bound to this network interface

getIndex

int getIndex()

Get the index of this network interface.

Returns:

the index of this network interface

getDisplayName

public String getDisplayName()

Get the display name of this network interface. A display name is a human readable String describing the network device.

Returns:

the display name of this network interface, or null if no display name is available.

getByName

public static NetworkInterface getByName(String name)
                                  throws SocketException

Searches for the network interface with the specified name.

Parameters:

name - The name of the network interface.

Returns:

A NetworkInterface with the specified name, or null if there is no network interface with the specified name.

Throws:

SocketException - If an I/O error occurs.

NullPointerException - If the specified name is null.

getByIndex

static NetworkInterface getByIndex(int index)
                            throws SocketException

Get a network interface given its index.

Parameters:

index - an integer, the index of the interface

Returns:

the NetworkInterface obtained from its index

Throws:

SocketException - if an I/O error occurs.

getByInetAddress

public static NetworkInterface getByInetAddress(InetAddress addr)
                                         throws SocketException

Convenience method to search for a network interface that has the specified Internet Protocol (IP) address bound to it.

If the specified IP address is bound to multiple network interfaces it is not defined which network interface is returned.

Parameters:

addr - The InetAddress to search with.

Returns:

A NetworkInterface or null if there is no network interface with the specified IP address.

Throws:

SocketException - If an I/O error occurs.

NullPointerException - If the specified address is null.

getNetworkInterfaces

public static Enumeration getNetworkInterfaces()
                                        throws SocketException

Returns all the interfaces on this machine. Returns null if no network interfaces could be found on this machine. NOTE: can use getNetworkInterfaces()+getInetAddresses() to obtain all IP addresses for this node

Returns:

an Enumeration of NetworkInterfaces found on this machine

Throws:

SocketException - if an I/O error occurs.

getAll

private static NetworkInterface[] getAll()
                                  throws SocketException

Throws:

SocketException

getByName0

private static NetworkInterface getByName0(String name)
                                    throws SocketException

Throws:

SocketException

getByInetAddress0

private static NetworkInterface getByInetAddress0(InetAddress addr)
                                           throws SocketException

Throws:

SocketException

equals

public boolean equals(Object obj)

Compares this object against the specified object. The result is true if and only if the argument is not null and it represents the same NetworkInterface as this object.

Two instances of NetworkInterface represent the same NetworkInterface if both name and addrs are the same for both.

Overrides:

equals in class Object

Parameters:

obj - the object to compare against.

Returns:

true if the objects are the same; false otherwise.

See Also:

InetAddress.getAddress()

hashCode

public int hashCode()

Description copied from class: Object

Returns a hash code value for the object. This method is supported for the benefit of hashtables such as those provided by java.util.Hashtable.

The general contract of hashCode is:

• Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
• If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
• It is not required that if two objects are unequal according to the Object.equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hashtables.

As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the Java^TM programming language.)

Overrides:

hashCode in class Object

Returns:

a hash code value for this object.

See Also:

Object.equals(java.lang.Object), Hashtable

toString

public String toString()

Description copied from class: Object

Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

 getClass().getName() + '@' + Integer.toHexString(hashCode())
 

Overrides:

toString in class Object

Returns:

a string representation of the object.

init

private static void init()