Module java.base
Package java.net

Class 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 Detail

      • getName

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

      • getInetAddresses

        public Enumeration<InetAddress> getInetAddresses​()
        Get 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
        See Also:
        inetAddresses()

      • inetAddresses

        public Stream<InetAddress> inetAddresses​()
        Get a Stream of 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 Stream. However, if the caller has the NetPermission("getNetworkInformation") permission, then all InetAddresses are returned.

        Returns:
        a Stream object with all or a subset of the InetAddresses bound to this network interface
        Since:
        9

      • 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
        See Also:
        subInterfaces()

      • subInterfaces

        public Stream<NetworkInterface> subInterfaces​()
        Get a Stream of all subinterfaces (also known as virtual interfaces) attached to this network interface.
        Returns:
        a Stream object with all of the subinterfaces of this network interface
        Since:
        9

      • 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

      • getIndex

        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
        Since:
        1.7
        See Also:
        getByIndex(int)

      • 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:
        a non-empty string representing 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

        public 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, 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
        Since:
        1.7
        See Also:
        getIndex()

      • 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 an Enumeration of 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.
        API Note:
        this method can be used in combination with 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, or if the platform does not have at least one configured network interface.
        See Also:
        networkInterfaces()

      • networkInterfaces

        public static Stream<NetworkInterface> networkInterfaces​()
                                                  throws SocketException
        Returns a Stream of all the interfaces on this machine. The Stream contains at least one interface, possibly representing a loopback interface that only supports communication between entities on this machine.
        API Note:
        this method can be used in combination with inetAddresses()} to obtain a stream of all IP addresses for this node, for example: 
         
 Stream<InetAddress> addrs = NetworkInterface.networkInterfaces()
     .flatMap(NetworkInterface::inetAddresses);
        Returns:
        a Stream of NetworkInterfaces found on this machine
        Throws:
        SocketException - if an I/O error occurs, or if the platform does not have at least one configured network interface.
        Since:
        9

      • 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. 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.
        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 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 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 hash tables.

        As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (The hashCode may or may not be implemented as some function of an object's memory address at some point in time.)

        Overrides:
        hashCode in class Object
        Returns:
        a hash code value for this object.
        See Also:
        Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

      • 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.