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".

Public Method Summary

boolean
equals(Object obj)
Compares this object against the specified object.
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.
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.
int
getIndex()
Returns the index of this network interface.
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 an integer hash code for this 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 containing a concise, human-readable description of this object.

Inherited Method Summary

Public Methods

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.

Parameters
obj the object to compare against.
Returns
  • true if the objects are the same; false otherwise.
See Also

public static NetworkInterface getByIndex (int index)

Get a network interface given its index.

Parameters
index an integer, the index of the interface
Returns
  • the NetworkInterface obtained from its index, or null if there is no interface with such an index on the system
Throws
SocketException if an I/O error occurs.
IllegalArgumentException if index has a negative value
See Also

public static NetworkInterface getByInetAddress (InetAddress addr)

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.

public static NetworkInterface getByName (String name)

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.

public String getDisplayName ()

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

Returns
  • a non-empty string representing the display name of this network interface, or null if no display name is available.

public 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. If a security manager is set, then the caller must have the permission NetPermission("getNetworkInformation").

Returns
  • a byte array containing the address, or null if the address doesn't exist, is not accessible or a security manager is set and the caller does not have the permission NetPermission("getNetworkInformation")
Throws
SocketException if an I/O error occurs.

public int getIndex ()

Returns the index of this network interface. The index is an integer greater or equal to zero, or -1 for unknown. This is a system specific value and interfaces with the same name can have different indexes on different machines.

Returns
  • the index of this network interface or -1 if the index is unknown
See Also

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. However, if the caller has the NetPermission("getNetworkInformation") permission, then all InetAddresses are returned.

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

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

public int getMTU ()

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.

public String getName ()

Get the name of this network interface.

Returns
  • the name of this network interface

public static Enumeration<NetworkInterface> getNetworkInterfaces ()

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.

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.

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

public int hashCode ()

Returns an integer hash code for this object. By contract, any two objects for which equals(Object) returns true must return the same hash code value. This means that subclasses of Object usually override both methods or neither method.

Note that hash values must not change over time unless information used in equals comparisons also changes.

See Writing a correct hashCode method if you intend implementing your own hashCode method.

Returns
  • this object's hash code.

public boolean isLoopback ()

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.

public boolean isPointToPoint ()

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.

public boolean isUp ()

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.

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.

public boolean supportsMulticast ()

Returns whether a network interface supports multicasting or not.

Returns
  • true if the interface supports Multicasting.
Throws
SocketException if an I/O error occurs.

public String toString ()

Returns a string containing a concise, human-readable description of this object. Subclasses are encouraged to override this method and provide an implementation that takes into account the object's type and data. The default implementation is equivalent to the following expression:

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

See Writing a useful toString method if you intend implementing your own toString method.

Returns
  • a printable representation of this object.