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NetworkInterface

public final class NetworkInterface
extends Object

java.lang.Object
   ↳ java.net.NetworkInterface


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".

Summary

Public methods

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 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.

Inherited methods

From class java.lang.Object

Public methods

equals

Added in API level 1
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 Object: the object to compare against.
Returns
boolean true if the objects are the same; false otherwise.

See also:

getByIndex

Added in API level 19
NetworkInterface getByIndex (int index)

Get a network interface given its index.

Parameters
index int: an integer, the index of the interface
Returns
NetworkInterface 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:

getByInetAddress

Added in API level 1
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 InetAddress: The InetAddress to search with.
Returns
NetworkInterface 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.

getByName

Added in API level 1
NetworkInterface getByName (String name)

Searches for the network interface with the specified name.

Parameters
name String: The name of the network interface.
Returns
NetworkInterface 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.

getDisplayName

Added in API level 1
String getDisplayName ()

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

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

getHardwareAddress

Added in API level 9
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
byte[] 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.

getIndex

Added in API level 19
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
int the index of this network interface or -1 if the index is unknown

See also:

getInetAddresses

Added in API level 1
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
Enumeration<InetAddress> an Enumeration object with all or a subset of the InetAddresses bound to this network interface

getInterfaceAddresses

Added in API level 9
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
List<InterfaceAddress> a List object with all or a subset of the InterfaceAddresss of this network interface

getMTU

Added in API level 9
int getMTU ()

Returns the Maximum Transmission Unit (MTU) of this interface.

Returns
int the value of the MTU for that interface.
Throws
SocketException if an I/O error occurs.

getName

Added in API level 1
String getName ()

Get the name of this network interface.

Returns
String the name of this network interface

getNetworkInterfaces

Added in API level 1
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
Enumeration<NetworkInterface> an Enumeration of NetworkInterfaces found on this machine
Throws
SocketException if an I/O error occurs.

getParent

Added in API level 9
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
NetworkInterface The NetworkInterface this interface is attached to.

getSubInterfaces

Added in API level 9
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
Enumeration<NetworkInterface> an Enumeration object with all of the subinterfaces of this network interface

hashCode

Added in API level 1
int hashCode ()

Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by HashMap.

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 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 hash tables.

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.)

Returns
int a hash code value for this object.

isLoopback

Added in API level 9
boolean isLoopback ()

Returns whether a network interface is a loopback interface.

Returns
boolean true if the interface is a loopback interface.
Throws
SocketException if an I/O error occurs.

isPointToPoint

Added in API level 9
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
boolean true if the interface is a point to point interface.
Throws
SocketException if an I/O error occurs.

isUp

Added in API level 9
boolean isUp ()

Returns whether a network interface is up and running.

Returns
boolean true if the interface is up and running.
Throws
SocketException if an I/O error occurs.

isVirtual

Added in API level 9
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
boolean true if this interface is a virtual interface.

supportsMulticast

Added in API level 9
boolean supportsMulticast ()

Returns whether a network interface supports multicasting or not.

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

toString

Added in API level 1
String toString ()

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())
 

Returns
String a string representation of the object.
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