DatagramSocketImpl (Java Platform SE 8 )
Keywords: java.net.DatagramSocketImpl class
Date: 2026-08-19

compact1, compact2, compact3
java.net

## Class DatagramSocketImpl

- java.lang.Object
- - java.net.DatagramSocketImpl

- All Implemented Interfaces:
    SocketOptions

      public abstract class DatagramSocketImpl
      extends Object
      implements SocketOptions

  Abstract datagram and multicast socket implementation base class.
  Since:
    JDK1.1

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected FileDescriptor` | `fd` The file descriptor object.
    `protected int` | `localPort` The local port number.

    - ### Fields inherited from interface java.net.SocketOptions

      `IP_MULTICAST_IF, IP_MULTICAST_IF2, IP_MULTICAST_LOOP, IP_TOS, SO_BINDADDR, SO_BROADCAST, SO_KEEPALIVE, SO_LINGER, SO_OOBINLINE, SO_RCVBUF, SO_REUSEADDR, SO_SNDBUF, SO_TIMEOUT, TCP_NODELAY`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `DatagramSocketImpl()`

  - ### Method Summary

    All Methods Instance Methods Abstract Methods Concrete Methods Deprecated Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected abstract void` | `bind(int lport, InetAddress laddr)` Binds a datagram socket to a local port and address.
    `protected abstract void` | `close()` Close the socket.
    `protected void` | `connect(InetAddress address, int port)` Connects a datagram socket to a remote destination.
    `protected abstract void` | `create()` Creates a datagram socket.
    `protected void` | `disconnect()` Disconnects a datagram socket from its remote destination.
    `protected FileDescriptor` | `getFileDescriptor()` Gets the datagram socket file descriptor.
    `protected int` | `getLocalPort()` Gets the local port.
    `protected abstract int` | `getTimeToLive()` Retrieve the TTL (time-to-live) option.
    `protected abstract byte` | `getTTL()` Deprecated. use getTimeToLive instead.
    `protected abstract void` | `join(InetAddress inetaddr)` Join the multicast group.
    `protected abstract void` | `joinGroup(SocketAddress mcastaddr, NetworkInterface netIf)` Join the multicast group.
    `protected abstract void` | `leave(InetAddress inetaddr)` Leave the multicast group.
    `protected abstract void` | `leaveGroup(SocketAddress mcastaddr, NetworkInterface netIf)` Leave the multicast group.
    `protected abstract int` | `peek(InetAddress i)` Peek at the packet to see who it is from.
    `protected abstract int` | `peekData(DatagramPacket p)` Peek at the packet to see who it is from.
    `protected abstract void` | `receive(DatagramPacket p)` Receive the datagram packet.
    `protected abstract void` | `send(DatagramPacket p)` Sends a datagram packet.
    `protected abstract void` | `setTimeToLive(int ttl)` Set the TTL (time-to-live) option.
    `protected abstract void` | `setTTL(byte ttl)` Deprecated. use setTimeToLive instead.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

    - ### Methods inherited from interface java.net.SocketOptions

      `getOption, setOption`

- - ### Field Detail

    - #### localPort

          protected int localPort

      The local port number.

    - #### fd

          protected FileDescriptor fd

      The file descriptor object.

  - ### Constructor Detail

    - #### DatagramSocketImpl

          public DatagramSocketImpl()

  - ### Method Detail

    - #### create

          protected abstract void create()
                                  throws SocketException

      Creates a datagram socket.
      Throws:
        `SocketException` - if there is an error in the underlying protocol, such as a TCP error.

    - #### bind

          protected abstract void bind(int lport,
                                       InetAddress laddr)
                                throws SocketException

      Binds a datagram socket to a local port and address.
      Parameters:
        `lport` - the local port
        `laddr` - the local address
      Throws:
        `SocketException` - if there is an error in the underlying protocol, such as a TCP error.

    - #### send

          protected abstract void send(DatagramPacket p)
                                throws IOException

      Sends a datagram packet. The packet contains the data and the destination address to send the packet to.
      Parameters:
        `p` - the packet to be sent.
      Throws:
        `IOException` - if an I/O exception occurs while sending the datagram packet.
        `PortUnreachableException` - may be thrown if the socket is connected to a currently unreachable destination. Note, there is no guarantee that the exception will be thrown.

    - #### connect

          protected void connect(InetAddress address,
                                 int port)
                          throws SocketException

      Connects a datagram socket to a remote destination. This associates the remote address with the local socket so that datagrams may only be sent to this destination and received from this destination. This may be overridden to call a native system connect.

      If the remote destination to which the socket is connected does not exist, or is otherwise unreachable, and if an ICMP destination unreachable packet has been received for that address, then a subsequent call to send or receive may throw a PortUnreachableException. Note, there is no guarantee that the exception will be thrown.

      Parameters:
        `address` - the remote InetAddress to connect to
        `port` - the remote port number
      Throws:
        `SocketException` - may be thrown if the socket cannot be connected to the remote destination
      Since:
        1.4

    - #### disconnect

          protected void disconnect()

      Disconnects a datagram socket from its remote destination.
      Since:
        1.4

    - #### peek

          protected abstract int peek(InetAddress i)
                               throws IOException

      Peek at the packet to see who it is from. Updates the specified `InetAddress` to the address which the packet came from.
      Parameters:
        `i` - an InetAddress object
      Returns:
        the port number which the packet came from.
      Throws:
        `IOException` - if an I/O exception occurs
        `PortUnreachableException` - may be thrown if the socket is connected to a currently unreachable destination. Note, there is no guarantee that the exception will be thrown.

    - #### peekData

          protected abstract int peekData(DatagramPacket p)
                                   throws IOException

      Peek at the packet to see who it is from. The data is copied into the specified `DatagramPacket`. The data is returned, but not consumed, so that a subsequent peekData/receive operation will see the same data.
      Parameters:
        `p` - the Packet Received.
      Returns:
        the port number which the packet came from.
      Throws:
        `IOException` - if an I/O exception occurs
        `PortUnreachableException` - may be thrown if the socket is connected to a currently unreachable destination. Note, there is no guarantee that the exception will be thrown.
      Since:
        1.4

    - #### receive

          protected abstract void receive(DatagramPacket p)
                                   throws IOException

      Receive the datagram packet.
      Parameters:
        `p` - the Packet Received.
      Throws:
        `IOException` - if an I/O exception occurs while receiving the datagram packet.
        `PortUnreachableException` - may be thrown if the socket is connected to a currently unreachable destination. Note, there is no guarantee that the exception will be thrown.

    - #### setTTL

          @Deprecated
          protected abstract void setTTL(byte ttl)
                                              throws IOException

      Deprecated. use setTimeToLive instead.
      Set the TTL (time-to-live) option.
      Parameters:
        `ttl` - a byte specifying the TTL value
      Throws:
        `IOException` - if an I/O exception occurs while setting the time-to-live option.
      See Also:
        `getTTL()`

    - #### getTTL

          @Deprecated
          protected abstract byte getTTL()
                                              throws IOException

      Deprecated. use getTimeToLive instead.
      Retrieve the TTL (time-to-live) option.
      Returns:
        a byte representing the TTL value
      Throws:
        `IOException` - if an I/O exception occurs while retrieving the time-to-live option
      See Also:
        `setTTL(byte)`

    - #### setTimeToLive

          protected abstract void setTimeToLive(int ttl)
                                         throws IOException

      Set the TTL (time-to-live) option.
      Parameters:
        `ttl` - an `int` specifying the time-to-live value
      Throws:
        `IOException` - if an I/O exception occurs while setting the time-to-live option.
      See Also:
        `getTimeToLive()`

    - #### getTimeToLive

          protected abstract int getTimeToLive()
                                        throws IOException

      Retrieve the TTL (time-to-live) option.
      Returns:
        an `int` representing the time-to-live value
      Throws:
        `IOException` - if an I/O exception occurs while retrieving the time-to-live option
      See Also:
        `setTimeToLive(int)`

    - #### join

          protected abstract void join(InetAddress inetaddr)
                                throws IOException

      Join the multicast group.
      Parameters:
        `inetaddr` - multicast address to join.
      Throws:
        `IOException` - if an I/O exception occurs while joining the multicast group.

    - #### leave

          protected abstract void leave(InetAddress inetaddr)
                                 throws IOException

      Leave the multicast group.
      Parameters:
        `inetaddr` - multicast address to leave.
      Throws:
        `IOException` - if an I/O exception occurs while leaving the multicast group.

    - #### joinGroup

          protected abstract void joinGroup(SocketAddress mcastaddr,
                                            NetworkInterface netIf)
                                     throws IOException

      Join the multicast group.
      Parameters:
        `mcastaddr` - address to join.
        `netIf` - specifies the local interface to receive multicast datagram packets
      Throws:
        `IOException` - if an I/O exception occurs while joining the multicast group
      Since:
        1.4

    - #### leaveGroup

          protected abstract void leaveGroup(SocketAddress mcastaddr,
                                             NetworkInterface netIf)
                                      throws IOException

      Leave the multicast group.
      Parameters:
        `mcastaddr` - address to leave.
        `netIf` - specified the local interface to leave the group at
      Throws:
        `IOException` - if an I/O exception occurs while leaving the multicast group
      Since:
        1.4

    - #### close

          protected abstract void close()

      Close the socket.

    - #### getLocalPort

          protected int getLocalPort()

      Gets the local port.
      Returns:
        an `int` representing the local port value

    - #### getFileDescriptor

          protected FileDescriptor getFileDescriptor()

      Gets the datagram socket file descriptor.
      Returns:
        a `FileDescriptor` object representing the datagram socket file descriptor

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