Added in API level 1

Summary: Methods | Inherited Methods

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".

Note that information about NetworkInterfaces may be restricted. For example, non-system apps will only have access to information about NetworkInterfaces that are associated with an InetAddress.

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 Object clone() Creates and returns a copy of this object. boolean equals(Object obj) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long timeoutMillis, int nanos) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait(long timeoutMillis) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait() Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Public methods

equals

Added in API level 1

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	Object: the object to compare against.

Returns
boolean	true if the objects are the same; false otherwise.

See also:

• InetAddress.getAddress()

getByIndex

Added in API level 19

public static 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 an interface with the specified index does not exist or can't be accessed.

Throws
SocketException	if an I/O error occurs.
IllegalArgumentException	if index has a negative value

See also:

• getIndex()

getByInetAddress

Added in API level 1

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	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

public static 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 the network interface with the specified name does not exist or can't be accessed.

Throws
SocketException	If an I/O error occurs.
NullPointerException	If the specified name is null.

getDisplayName

Added in API level 1

public 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

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
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"). For example, this method will generally return null when called by non-system apps (or 02:00:00:00:00:00 for apps having targetSdkVersion < android.os.Build.VERSION_CODES.R).

Throws
SocketException	if an I/O error occurs.

getIndex

Added in API level 19

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
int	the index of this network interface or -1 if the index is unknown

See also:

• getByIndex(int)

getInetAddresses

Added in API level 1

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

getInterfaceAddresses

Added in API level 9

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
List<InterfaceAddress>	a List object with all or a subset of the InterfaceAddresss of this network interface

getMTU

Added in API level 9

public 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

public String getName ()

Get the name of this network interface.

Returns
String	the name of this network interface

getNetworkInterfaces

Added in API level 1

public static Enumeration<NetworkInterface> getNetworkInterfaces ()

Returns all the interfaces on this machine. The Enumeration contains at least one element, possibly representing a loopback interface that only supports communication between entities on this machine. NOTE: can use getNetworkInterfaces()+getInetAddresses() to obtain all IP addresses for this node

For non-system apps, this method will only return information for NetworkInterfaces associated with an InetAddress.

ANDROID NOTE: On Android versions before S (API level 31), this method may throw a NullPointerException if called in an environment where there is a virtual interface without a parent interface present.

Returns
Enumeration<NetworkInterface>	an Enumeration of NetworkInterfaces found on this machine that are accessible.

Throws
SocketException	if an I/O error occurs.

getParent

Added in API level 9

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
NetworkInterface	The NetworkInterface this interface is attached to.

getSubInterfaces

Added in API level 9

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
Enumeration<NetworkInterface>	an Enumeration object with all of the subinterfaces of this network interface

hashCode

Added in API level 1

public 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 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 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.

Returns
int	a hash code value for this object.

isLoopback

Added in API level 9

public 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

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
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

public 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

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
boolean	true if this interface is a virtual interface.

supportsMulticast

Added in API level 9

public 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

public String toString ()

Returns a string representation of the object.

Returns
String	a string representation of the object.