Java™ Platform
Standard Ed. 6

java.net
Class NetworkInterface

java.lang.Object
  extended by 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

Method Summary
 boolean equals(Object obj)
          Compares this object against the specified object.
static NetworkInterface getByInetAddress(InetAddress addr)
          Convenience method to search for a network interface that has the specified Internet Protocol (IP) address bound to it.
static NetworkInterface getByName(String name)
          Searches for the network interface with the specified name.
 String getDisplayName()
          Get the display name of this network interface.
 byte[] getHardwareAddress()
          Returns the hardware address (usually MAC) of the interface if it has one and if it can be accessed given the current privileges.
 Enumeration<InetAddress> getInetAddresses()
          Convenience method to return an Enumeration with all or a subset of the InetAddresses bound to this network interface.
 List<InterfaceAddress> getInterfaceAddresses()
          Get a List of all or a subset of the InterfaceAddresses of this network interface.
 int getMTU()
          Returns the Maximum Transmission Unit (MTU) of this interface.
 String getName()
          Get the name of this network interface.
static Enumeration<NetworkInterface> getNetworkInterfaces()
          Returns all the interfaces on this machine.
 NetworkInterface getParent()
          Returns the parent NetworkInterface of this interface if this is a subinterface, or null if it is a physical (non virtual) interface or has no parent.
 Enumeration<NetworkInterface> getSubInterfaces()
          Get an Enumeration with all the subinterfaces (also known as virtual interfaces) attached to this network interface.
 int hashCode()
          Returns a hash code value for the object.
 boolean isLoopback()
          Returns whether a network interface is a loopback interface.
 boolean isPointToPoint()
          Returns whether a network interface is a point to point interface.
 boolean isUp()
          Returns whether a network interface is up and running.
 boolean isVirtual()
          Returns whether this interface is a virtual interface (also called subinterface).
 boolean supportsMulticast()
          Returns whether a network interface supports multicasting or not.
 String toString()
          Returns a string representation of the object.
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 

Method Detail

getName

public String getName()
Get the name of this network interface.

Returns:
the name of this network interface

getInetAddresses

public Enumeration<InetAddress> 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

getInterfaceAddresses

public List<InterfaceAddress> getInterfaceAddresses()
Get a List of all or a subset of the InterfaceAddresses of this network interface.

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

Returns:
a List object with all or a subset of the InterfaceAddresss of this network interface
Since:
1.6

getSubInterfaces

public Enumeration<NetworkInterface> getSubInterfaces()
Get an Enumeration with all the subinterfaces (also known as virtual interfaces) attached to this network interface.

For instance eth0:1 will be a subinterface to eth0.

Returns:
an Enumeration object with all of the subinterfaces of this network interface
Since:
1.6

getParent

public NetworkInterface getParent()
Returns the parent NetworkInterface of this interface if this is a subinterface, or null if it is a physical (non virtual) interface or has no parent.

Returns:
The NetworkInterface this interface is attached to.
Since:
1.6

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.

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<NetworkInterface> 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.

isUp

public boolean isUp()
             throws SocketException
Returns whether a network interface is up and running.

Returns:
true if the interface is up and running.
Throws:
SocketException - if an I/O error occurs.
Since:
1.6

isLoopback

public boolean isLoopback()
                   throws SocketException
Returns whether a network interface is a loopback interface.

Returns:
true if the interface is a loopback interface.
Throws:
SocketException - if an I/O error occurs.
Since:
1.6

isPointToPoint

public boolean isPointToPoint()
                       throws SocketException
Returns whether a network interface is a point to point interface. A typical point to point interface would be a PPP connection through a modem.

Returns:
true if the interface is a point to point interface.
Throws:
SocketException - if an I/O error occurs.
Since:
1.6

supportsMulticast

public boolean supportsMulticast()
                          throws SocketException
Returns whether a network interface supports multicasting or not.

Returns:
true if the interface supports Multicasting.
Throws:
SocketException - if an I/O error occurs.
Since:
1.6

getHardwareAddress

public byte[] getHardwareAddress()
                          throws SocketException
Returns the hardware address (usually MAC) of the interface if it has one and if it can be accessed given the current privileges.

Returns:
a byte array containing the address or null if the address doesn't exist or is not accessible.
Throws:
SocketException - if an I/O error occurs.
Since:
1.6

getMTU

public int getMTU()
           throws SocketException
Returns the Maximum Transmission Unit (MTU) of this interface.

Returns:
the value of the MTU for that interface.
Throws:
SocketException - if an I/O error occurs.
Since:
1.6

isVirtual

public boolean isVirtual()
Returns whether this interface is a virtual interface (also called subinterface). Virtual interfaces are, on some systems, interfaces created as a child of a physical interface and given different settings (like address or MTU). Usually the name of the interface will the name of the parent followed by a colon (:) and a number identifying the child since there can be several virtual interfaces attached to a single physical interface.

Returns:
true if this interface is a virtual interface.
Since:
1.6

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:

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 JavaTM 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.

Java™ Platform
Standard Ed. 6

Submit a bug or feature
For further API reference and developer documentation, see Java SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Copyright 2008 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.


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