Module java.base
Package java.net

Class Inet6Address

java.lang.Object
java.net.InetAddress
java.net.Inet6Address
All Implemented Interfaces:
Serializable
public final class Inet6Address
extends InetAddress
This class represents an Internet Protocol version 6 (IPv6) address. Defined by RFC 2373: IP Version 6 Addressing Architecture.

Textual representation of IP addresses

Textual representation of IPv6 address used as input to methods takes one of the following forms:

  1. The preferred form is x:x:x:x:x:x:x:x, where the 'x's are the hexadecimal values of the eight 16-bit pieces of the address. This is the full form. For example,

    • 1080:0:0:0:8:800:200C:417A

    Note that it is not necessary to write the leading zeros in an individual field. However, there must be at least one numeral in every field, except as described below.

  2. Due to some methods of allocating certain styles of IPv6 addresses, it will be common for addresses to contain long strings of zero bits. In order to make writing addresses containing zero bits easier, a special syntax is available to compress the zeros. The use of "::" indicates multiple groups of 16-bits of zeros. The "::" can only appear once in an address. The "::" can also be used to compress the leading and/or trailing zeros in an address. For example,

    • 1080::8:800:200C:417A

  3. An alternative form that is sometimes more convenient when dealing with a mixed environment of IPv4 and IPv6 nodes is x:x:x:x:x:x:d.d.d.d, where the 'x's are the hexadecimal values of the six high-order 16-bit pieces of the address, and the 'd's are the decimal values of the four low-order 8-bit pieces of the standard IPv4 representation address, for example,

    • ::FFFF:129.144.52.38
    • ::129.144.52.38

    where "::FFFF:d.d.d.d" and "::d.d.d.d" are, respectively, the general forms of an IPv4-mapped IPv6 address and an IPv4-compatible IPv6 address. Note that the IPv4 portion must be in the "d.d.d.d" form. The following forms are invalid:

    • ::FFFF:d.d.d
    • ::FFFF:d.d
    • ::d.d.d
    • ::d.d

    The following form:

    • ::FFFF:d

    is valid, however it is an unconventional representation of the IPv4-compatible IPv6 address,

    • ::255.255.0.d

    while "::d" corresponds to the general IPv6 address "0:0:0:0:0:0:0:d".

For methods that return a textual representation as output value, the full form is used. Inet6Address will return the full form because it is unambiguous when used in combination with other textual data.

Special IPv6 address

Description of IPv4-mapped address
IPv4-mapped address Of the form ::ffff:w.x.y.z, this IPv6 address is used to represent an IPv4 address. It allows the native program to use the same address data structure and also the same socket when communicating with both IPv4 and IPv6 nodes.

In InetAddress and Inet6Address, it is used for internal representation; it has no functional role. Java will never return an IPv4-mapped address. These classes can take an IPv4-mapped address as input, both in byte array and text representation. However, it will be converted into an IPv4 address.

Textual representation of IPv6 scoped addresses

The textual representation of IPv6 addresses as described above can be extended to specify IPv6 scoped addresses. This extension to the basic addressing architecture is described in [draft-ietf-ipngwg-scoping-arch-04.txt].

Because link-local and site-local addresses are non-global, it is possible that different hosts may have the same destination address and may be reachable through different interfaces on the same originating system. In this case, the originating system is said to be connected to multiple zones of the same scope. In order to disambiguate which is the intended destination zone, it is possible to append a zone identifier (or scope_id) to an IPv6 address.

The general format for specifying the scope_id is the following:

IPv6-address%scope_id

The IPv6-address is a literal IPv6 address as described above. The scope_id refers to an interface on the local system, and it can be specified in two ways.

  1. As a numeric identifier. This must be a positive integer that identifies the particular interface and scope as understood by the system. Usually, the numeric values can be determined through administration tools on the system. Each interface may have multiple values, one for each scope. If the scope is unspecified, then the default value used is zero.
  2. As a string. This must be the exact string that is returned by NetworkInterface.getName() for the particular interface in question. When an Inet6Address is created in this way, the numeric scope-id is determined at the time the object is created by querying the relevant NetworkInterface.

Note also, that the numeric scope_id can be retrieved from Inet6Address instances returned from the NetworkInterface class. This can be used to find out the current scope ids configured on the system.

Since:
1.4
See Also:
Serialized Form

  • Method Details

    • getByAddress

      public static Inet6Address getByAddress​(String host, byte[] addr, NetworkInterface nif) throws UnknownHostException
      Create an Inet6Address in the exact manner of InetAddress.getByAddress(String,byte[]) except that the IPv6 scope_id is set to the value corresponding to the given interface for the address type specified in addr. The call will fail with an UnknownHostException if the given interface does not have a numeric scope_id assigned for the given address type (e.g. link-local or site-local). See here for a description of IPv6 scoped addresses.
      Parameters:
      host - the specified host
      addr - the raw IP address in network byte order
      nif - an interface this address must be associated with.
      Returns:
      an Inet6Address object created from the raw IP address.
      Throws:
      UnknownHostException - if IP address is of illegal length, or if the interface does not have a numeric scope_id assigned for the given address type.
      Since:
      1.5

    • getByAddress

      public static Inet6Address getByAddress​(String host, byte[] addr, int scope_id) throws UnknownHostException
      Create an Inet6Address in the exact manner of InetAddress.getByAddress(String,byte[]) except that the IPv6 scope_id is set to the given numeric value. The scope_id is not checked to determine if it corresponds to any interface on the system. See here for a description of IPv6 scoped addresses.
      Parameters:
      host - the specified host
      addr - the raw IP address in network byte order
      scope_id - the numeric scope_id for the address.
      Returns:
      an Inet6Address object created from the raw IP address.
      Throws:
      UnknownHostException - if IP address is of illegal length.
      Since:
      1.5

    • isMulticastAddress

      public boolean isMulticastAddress()
      Utility routine to check if the InetAddress is an IP multicast address. 11111111 at the start of the address identifies the address as being a multicast address.
      Overrides:
      isMulticastAddress in class InetAddress
      Returns:
      a boolean indicating if the InetAddress is an IP multicast address

    • isAnyLocalAddress

      public boolean isAnyLocalAddress()
      Utility routine to check if the InetAddress is a wildcard address.
      Overrides:
      isAnyLocalAddress in class InetAddress
      Returns:
      a boolean indicating if the InetAddress is a wildcard address.

    • isLoopbackAddress

      public boolean isLoopbackAddress()
      Utility routine to check if the InetAddress is a loopback address.
      Overrides:
      isLoopbackAddress in class InetAddress
      Returns:
      a boolean indicating if the InetAddress is a loopback address; or false otherwise.

    • isLinkLocalAddress

      public boolean isLinkLocalAddress()
      Utility routine to check if the InetAddress is an link local address.
      Overrides:
      isLinkLocalAddress in class InetAddress
      Returns:
      a boolean indicating if the InetAddress is a link local address; or false if address is not a link local unicast address.

    • isSiteLocalAddress

      public boolean isSiteLocalAddress()
      Utility routine to check if the InetAddress is a site local address.
      Overrides:
      isSiteLocalAddress in class InetAddress
      Returns:
      a boolean indicating if the InetAddress is a site local address; or false if address is not a site local unicast address.

    • isMCGlobal

      public boolean isMCGlobal()
      Utility routine to check if the multicast address has global scope.
      Overrides:
      isMCGlobal in class InetAddress
      Returns:
      a boolean indicating if the address has is a multicast address of global scope, false if it is not of global scope or it is not a multicast address

    • isMCNodeLocal

      public boolean isMCNodeLocal()
      Utility routine to check if the multicast address has node scope.
      Overrides:
      isMCNodeLocal in class InetAddress
      Returns:
      a boolean indicating if the address has is a multicast address of node-local scope, false if it is not of node-local scope or it is not a multicast address

    • isMCLinkLocal

      public boolean isMCLinkLocal()
      Utility routine to check if the multicast address has link scope.
      Overrides:
      isMCLinkLocal in class InetAddress
      Returns:
      a boolean indicating if the address has is a multicast address of link-local scope, false if it is not of link-local scope or it is not a multicast address

    • isMCSiteLocal

      public boolean isMCSiteLocal()
      Utility routine to check if the multicast address has site scope.
      Overrides:
      isMCSiteLocal in class InetAddress
      Returns:
      a boolean indicating if the address has is a multicast address of site-local scope, false if it is not of site-local scope or it is not a multicast address

    • isMCOrgLocal

      public boolean isMCOrgLocal()
      Utility routine to check if the multicast address has organization scope.
      Overrides:
      isMCOrgLocal in class InetAddress
      Returns:
      a boolean indicating if the address has is a multicast address of organization-local scope, false if it is not of organization-local scope or it is not a multicast address

    • getAddress

      public byte[] getAddress()
      Returns the raw IP address of this InetAddress object. The result is in network byte order: the highest order byte of the address is in getAddress()[0].
      Overrides:
      getAddress in class InetAddress
      Returns:
      the raw IP address of this object.

    • getScopeId

      public int getScopeId()
      Returns the numeric scopeId, if this instance is associated with an interface. If no scoped_id is set, the returned value is zero.
      Returns:
      the scopeId, or zero if not set.
      Since:
      1.5

    • getScopedInterface

      public NetworkInterface getScopedInterface()
      Returns the scoped interface, if this instance was created with a scoped interface.
      Returns:
      the scoped interface, or null if not set.
      Since:
      1.5

    • getHostAddress

      public String getHostAddress()
      Returns the IP address string in textual presentation. If the instance was created specifying a scope identifier then the scope id is appended to the IP address preceded by a "%" (per-cent) character. This can be either a numeric value or a string, depending on which was used to create the instance.
      Overrides:
      getHostAddress in class InetAddress
      Returns:
      the raw IP address in a string format.

    • hashCode

      public int hashCode()
      Returns a hashcode for this IP address.
      Overrides:
      hashCode in class InetAddress
      Returns:
      a hash code value for this IP address.
      See Also:
      Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

    • 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 IP address as this object.

      Two instances of InetAddress represent the same IP address if the length of the byte arrays returned by getAddress is the same for both, and each of the array components is the same for the byte arrays.

      Overrides:
      equals in class InetAddress
      Parameters:
      obj - the object to compare against.
      Returns:
      true if the objects are the same; false otherwise.
      See Also:
      InetAddress.getAddress()

    • isIPv4CompatibleAddress

      public boolean isIPv4CompatibleAddress()
      Utility routine to check if the InetAddress is an IPv4 compatible IPv6 address.
      Returns:
      a boolean indicating if the InetAddress is an IPv4 compatible IPv6 address; or false if address is IPv4 address.