1. Description
2. Constructor Summary
3. Method Summary
4. Constructor Details
   1. Socket()
   2. Socket(Proxy)
   3. Socket(SocketImpl)
   4. Socket(String, int)
   5. Socket(InetAddress, int)
   6. Socket(String, int, InetAddress, int)
   7. Socket(InetAddress, int, InetAddress, int)
   8. Socket(String, int, boolean)
   9. Socket(InetAddress, int, boolean)
5. Method Details
   1. connect(SocketAddress)
   2. connect(SocketAddress, int)
   3. bind(SocketAddress)
   4. getInetAddress()
   5. getLocalAddress()
   6. getPort()
   7. getLocalPort()
   8. getRemoteSocketAddress()
   9. getLocalSocketAddress()
   10. getChannel()
   11. getInputStream()
   12. getOutputStream()
   13. setTcpNoDelay(boolean)
   14. getTcpNoDelay()
   15. setSoLinger(boolean, int)
   16. getSoLinger()
   17. sendUrgentData(int)
   18. setOOBInline(boolean)
   19. getOOBInline()
   20. setSoTimeout(int)
   21. getSoTimeout()
   22. setSendBufferSize(int)
   23. getSendBufferSize()
   24. setReceiveBufferSize(int)
   25. getReceiveBufferSize()
   26. setKeepAlive(boolean)
   27. getKeepAlive()
   28. setTrafficClass(int)
   29. getTrafficClass()
   30. setReuseAddress(boolean)
   31. getReuseAddress()
   32. close()
   33. shutdownInput()
   34. shutdownOutput()
   35. toString()
   36. isConnected()
   37. isBound()
   38. isClosed()
   39. isInputShutdown()
   40. isOutputShutdown()
   41. setSocketImplFactory(SocketImplFactory)
   42. setPerformancePreferences(int, int, int)
   43. setOption(SocketOption, T)
   44. getOption(SocketOption)
   45. supportedOptions()

• Constructor Summary

  Constructors
  Modifier

  Constructor

  Description

   

  Socket()

  Creates an unconnected Socket.

   

  Socket(String host, int port)

  Creates a stream socket and connects it to the specified port number on the named host.

   

  Socket(String host, int port, boolean stream)

  Deprecated, for removal: This API element is subject to removal in a future version.

  The stream parameter provided a way in early JDK releases to create a Socket that used a datagram socket.

   

  Socket(String host, int port, InetAddress localAddr, int localPort)

  Creates a socket and connects it to the specified remote host on the specified remote port.

   

  Socket(InetAddress address, int port)

  Creates a stream socket and connects it to the specified port number at the specified IP address.

   

  Socket(InetAddress host, int port, boolean stream)

  Deprecated, for removal: This API element is subject to removal in a future version.

  The stream parameter provided a way in early JDK releases to create a Socket that used a datagram socket.

   

  Socket(InetAddress address, int port, InetAddress localAddr, int localPort)

  Creates a socket and connects it to the specified remote address on the specified remote port.

   

  Socket(Proxy proxy)

  Creates an unconnected socket, specifying the type of proxy, if any, that should be used regardless of any other settings.

  protected

  Socket(SocketImpl impl)

  Creates an unconnected Socket with a user-specified SocketImpl.

• Method Summary

  All MethodsStatic MethodsInstance MethodsConcrete MethodsDeprecated Methods

  Modifier and Type

  Method

  Description

  void

  bind(SocketAddress bindpoint)

  Binds the socket to a local address.

  void

  close()

  Closes this socket.

  void

  connect(SocketAddress endpoint)

  Connects this socket to the server.

  void

  connect(SocketAddress endpoint, int timeout)

  Connects this socket to the server with a specified timeout value.

  SocketChannel

  getChannel()

  Returns the unique SocketChannel object associated with this socket, if any.

  InetAddress

  getInetAddress()

  Returns the address to which the socket is connected.

  InputStream

  getInputStream()

  Returns an input stream for this socket.

  boolean

  getKeepAlive()

  Tests if SO_KEEPALIVE is enabled.

  InetAddress

  getLocalAddress()

  Gets the local address to which the socket is bound.

  int

  getLocalPort()

  Returns the local port number to which this socket is bound.

  SocketAddress

  getLocalSocketAddress()

  Returns the address of the endpoint this socket is bound to.

  boolean

  getOOBInline()

  Tests if SO_OOBINLINE is enabled.

  <T> T

  getOption(SocketOption<T> name)

  Returns the value of a socket option.

  OutputStream

  getOutputStream()

  Returns an output stream for this socket.

  int

  getPort()

  Returns the remote port number to which this socket is connected.

  int

  getReceiveBufferSize()

  Gets the value of the SO_RCVBUF option for this Socket, that is the buffer size used by the platform for input on this Socket.

  SocketAddress

  getRemoteSocketAddress()

  Returns the address of the endpoint this socket is connected to, or null if it is unconnected.

  boolean

  getReuseAddress()

  Tests if SO_REUSEADDR is enabled.

  int

  getSendBufferSize()

  Get value of the SO_SNDBUF option for this Socket, that is the buffer size used by the platform for output on this Socket.

  int

  getSoLinger()

  Returns setting for SO_LINGER. -1 returns implies that the option is disabled.

  int

  getSoTimeout()

  Returns setting for SO_TIMEOUT. 0 returns implies that the option is disabled (i.e., timeout of infinity).

  boolean

  getTcpNoDelay()

  Tests if TCP_NODELAY is enabled.

  int

  getTrafficClass()

  Gets traffic class or type-of-service in the IP header for packets sent from this Socket

  boolean

  isBound()

  Returns the binding state of the socket.

  boolean

  isClosed()

  Returns the closed state of the socket.

  boolean

  isConnected()

  Returns the connection state of the socket.

  boolean

  isInputShutdown()

  Returns whether the read-half of the socket connection is closed.

  boolean

  isOutputShutdown()

  Returns whether the write-half of the socket connection is closed.

  void

  sendUrgentData(int data)

  Send one byte of urgent data on the socket.

  void

  setKeepAlive(boolean on)

  Enable/disable SO_KEEPALIVE.

  void

  setOOBInline(boolean on)

  Enable/disable SO_OOBINLINE (receipt of TCP urgent data) By default, this option is disabled and TCP urgent data received on a socket is silently discarded.

  <T> Socket

  setOption(SocketOption<T> name, T value)

  Sets the value of a socket option.

  void

  setPerformancePreferences(int connectionTime, int latency, int bandwidth)

  Deprecated, for removal: This API element is subject to removal in a future version.

  This method was intended to allow for protocols that are now obsolete.

  void

  setReceiveBufferSize(int size)

  Sets the SO_RCVBUF option to the specified value for this Socket.

  void

  setReuseAddress(boolean on)

  Enable/disable the SO_REUSEADDR socket option.

  void

  setSendBufferSize(int size)

  Sets the SO_SNDBUF option to the specified value for this Socket.

  static void

  setSocketImplFactory(SocketImplFactory fac)

  Deprecated.

  Use a SocketFactory and subclass Socket directly.

  void

  setSoLinger(boolean on, int linger)

  Enable/disable SO_LINGER with the specified linger time in seconds.

  void

  setSoTimeout(int timeout)

  Enable/disable SO_TIMEOUT with the specified timeout, in milliseconds.

  void

  setTcpNoDelay(boolean on)

  Enable/disable TCP_NODELAY (disable/enable Nagle's algorithm).

  void

  setTrafficClass(int tc)

  Sets traffic class or type-of-service octet in the IP header for packets sent from this Socket.

  void

  shutdownInput()

  Places the input stream for this socket at "end of stream".

  void

  shutdownOutput()

  Disables the output stream for this socket.

  Set<SocketOption<?>>

  supportedOptions()

  Returns a set of the socket options supported by this socket.

  String

  toString()

  Converts this socket to a String.

  Methods declared in class Object

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

  Modifier and Type

  Method

  Description

  protected Object

  clone()

  Creates and returns a copy of this object.

  boolean

  equals(Object obj)

  Indicates whether some other object is "equal to" this one.

  protected void

  finalize()

  Deprecated, for removal: This API element is subject to removal in a future version.

  Finalization is deprecated and subject to removal in a future release.

  final Class<?>

  getClass()

  Returns the runtime class of this Object.

  int

  hashCode()

  Returns a hash code value for this 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.

  final void

  wait()

  Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

  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(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.

• Constructor Details

  • Socket

    public Socket()

    Creates an unconnected Socket.

    If the application has specified a client socket implementation factory, that factory's createSocketImpl method is called to create the actual socket implementation. Otherwise a system-default socket implementation is created.

    Since: 1.1

  • Socket

    public Socket(Proxy proxy)

    Creates an unconnected socket, specifying the type of proxy, if any, that should be used regardless of any other settings.

    Examples:

    • Socket s = new Socket(Proxy.NO_PROXY); will create a plain socket ignoring any other proxy configuration.
    • Socket s = new Socket(new Proxy(Proxy.Type.SOCKS, new InetSocketAddress("socks.mydom.com", 1080))); will create a socket connecting through the specified SOCKS proxy server.

    Parameters: proxy - a Proxy object specifying what kind of proxying should be used. Throws: IllegalArgumentException - if the proxy is of an invalid type or null. Since: 1.5 See Also:

    • ProxySelector
    • Proxy

  • Socket

    protected Socket(SocketImpl impl) throws SocketException

    Creates an unconnected Socket with a user-specified SocketImpl.

    Parameters: impl - an instance of a SocketImpl the subclass wishes to use on the Socket. Throws: SocketException - if there is an error in the underlying protocol, such as a TCP error. Since: 1.1

  • Socket

    public Socket(String host, int port) throws UnknownHostException, IOException

    Creates a stream socket and connects it to the specified port number on the named host.

    If the specified host is null it is the equivalent of specifying the address as InetAddress.getByName(null). In other words, it is equivalent to specifying an address of the loopback interface.

    If the application has specified a client socket implementation factory, that factory's createSocketImpl method is called to create the actual socket implementation. Otherwise a system-default socket implementation is created.

    Parameters: host - the host name, or null for the loopback address. port - the port number. Throws: UnknownHostException - if the IP address of the host could not be determined. IOException - if an I/O error occurs when creating the socket. IllegalArgumentException - if the port parameter is outside the specified range of valid port values, which is between 0 and 65535, inclusive.

  • Socket

    public Socket(InetAddress address, int port) throws IOException

    Creates a stream socket and connects it to the specified port number at the specified IP address.

    If the application has specified a client socket implementation factory, that factory's createSocketImpl method is called to create the actual socket implementation. Otherwise a system-default socket implementation is created.

    Parameters: address - the IP address. port - the port number. Throws: IOException - if an I/O error occurs when creating the socket. IllegalArgumentException - if the port parameter is outside the specified range of valid port values, which is between 0 and 65535, inclusive. NullPointerException - if address is null.

  • Socket

    public Socket(String host, int port, InetAddress localAddr, int localPort) throws IOException

    Creates a socket and connects it to the specified remote host on the specified remote port. The Socket will also bind() to the local address and port supplied.

    If the specified host is null it is the equivalent of specifying the address as InetAddress.getByName(null). In other words, it is equivalent to specifying an address of the loopback interface.

    A local port number of zero will let the system pick up a free port in the bind operation.

    Parameters: host - the name of the remote host, or null for the loopback address. port - the remote port localAddr - the local address the socket is bound to, or null for the anyLocal address. localPort - the local port the socket is bound to, or zero for a system selected free port. Throws: IOException - if an I/O error occurs when creating the socket. IllegalArgumentException - if the port parameter or localPort parameter is outside the specified range of valid port values, which is between 0 and 65535, inclusive. Since: 1.1

  • Socket

    public Socket(InetAddress address, int port, InetAddress localAddr, int localPort) throws IOException

    Creates a socket and connects it to the specified remote address on the specified remote port. The Socket will also bind() to the local address and port supplied.

    If the specified local address is null it is the equivalent of specifying the address as the AnyLocal address (see InetAddress.isAnyLocalAddress()).

    A local port number of zero will let the system pick up a free port in the bind operation.

    Parameters: address - the remote address port - the remote port localAddr - the local address the socket is bound to, or null for the anyLocal address. localPort - the local port the socket is bound to or zero for a system selected free port. Throws: IOException - if an I/O error occurs when creating the socket. IllegalArgumentException - if the port parameter or localPort parameter is outside the specified range of valid port values, which is between 0 and 65535, inclusive. NullPointerException - if address is null. Since: 1.1

  • Socket

    @Deprecated(forRemoval=true, since="1.1") public Socket(String host, int port, boolean stream) throws IOException

    Deprecated, for removal: This API element is subject to removal in a future version.

    The stream parameter provided a way in early JDK releases to create a Socket that used a datagram socket. This feature no longer exists. Instead use DatagramSocket for datagram sockets.

    Creates a stream socket and connects it to the specified port number on the named host.

    If the specified host is null it is the equivalent of specifying the address as InetAddress.getByName(null). In other words, it is equivalent to specifying an address of the loopback interface.

    If the application has specified a client socket implementation factory, that factory's createSocketImpl method is called to create the actual socket implementation. Otherwise a system-default socket implementation is created.

    Parameters: host - the host name, or null for the loopback address. port - the port number. stream - must be true, false is not allowed. Throws: IOException - if an I/O error occurs when creating the socket. IllegalArgumentException - if the stream parameter is false or if the port parameter is outside the specified range of valid port values, which is between 0 and 65535, inclusive.

  • Socket

    @Deprecated(forRemoval=true, since="1.1") public Socket(InetAddress host, int port, boolean stream) throws IOException

    Deprecated, for removal: This API element is subject to removal in a future version.

    The stream parameter provided a way in early JDK releases to create a Socket that used a datagram socket. This feature no longer exists. Instead use DatagramSocket for datagram sockets.

    Creates a socket and connects it to the specified port number at the specified IP address.

    If the application has specified a client socket implementation factory, that factory's createSocketImpl method is called to create the actual socket implementation. Otherwise a system-default socket implementation is created.

    Parameters: host - the IP address. port - the port number. stream - must be true, false is not allowed. Throws: IOException - if an I/O error occurs when creating the socket. IllegalArgumentException - if the stream parameter is false or if the port parameter is outside the specified range of valid port values, which is between 0 and 65535, inclusive. NullPointerException - if host is null.

• Method Details

  • connect

    public void connect(SocketAddress endpoint) throws IOException

    Connects this socket to the server.

    If the connection cannot be established, then the socket is closed, and an IOException is thrown.

    This method is interruptible in the following circumstances:

    1. The socket is associated with a SocketChannel. In that case, interrupting a thread establishing a connection will close the underlying channel and cause this method to throw ClosedByInterruptException with the thread's interrupted status set.
    2. The socket uses the system-default socket implementation and a virtual thread is establishing a connection. In that case, interrupting the virtual thread will cause it to wakeup and close the socket. This method will then throw SocketException with the thread's interrupted status set.

    Parameters: endpoint - the SocketAddress Throws: IOException - if an error occurs during the connection, the socket is already connected or the socket is closed UnknownHostException - if the connection could not be established because the endpoint is an unresolved InetSocketAddress IllegalBlockingModeException - if this socket has an associated channel, and the channel is in non-blocking mode IllegalArgumentException - if endpoint is null or is a SocketAddress subclass not supported by this socket Since: 1.4

  • connect

    public void connect(SocketAddress endpoint, int timeout) throws IOException

    Connects this socket to the server with a specified timeout value. A timeout of zero is interpreted as an infinite timeout. The connection will then block until established or an error occurs.

    If the connection cannot be established, or the timeout expires before the connection is established, then the socket is closed, and an IOException is thrown.

    This method is interruptible in the following circumstances:

    1. The socket is associated with a SocketChannel. In that case, interrupting a thread establishing a connection will close the underlying channel and cause this method to throw ClosedByInterruptException with the thread's interrupted status set.
    2. The socket uses the system-default socket implementation and a virtual thread is establishing a connection. In that case, interrupting the virtual thread will cause it to wakeup and close the socket. This method will then throw SocketException with the thread's interrupted status set.

    API Note: Establishing a TCP/IP connection is subject to connect timeout settings in the operating system. The typical operating system timeout is in the range of tens of seconds to minutes. If the operating system timeout expires before the timeout specified to this method then an IOException is thrown. The timeout specified to this method is typically a timeout value that is shorter than the operating system timeout. Parameters: endpoint - the SocketAddress timeout - the timeout value to be used in milliseconds. Throws: IOException - if an error occurs during the connection, the socket is already connected or the socket is closed SocketTimeoutException - if timeout expires before connecting UnknownHostException - if the connection could not be established because the endpoint is an unresolved InetSocketAddress IllegalBlockingModeException - if this socket has an associated channel, and the channel is in non-blocking mode IllegalArgumentException - if endpoint is null or is a SocketAddress subclass not supported by this socket, or if timeout is negative Since: 1.4

  • bind

    public void bind(SocketAddress bindpoint) throws IOException

    Binds the socket to a local address.

    If the address is null, then the system will pick up an ephemeral port and a valid local address to bind the socket.

    Parameters: bindpoint - the SocketAddress to bind to Throws: IOException - if the bind operation fails, the socket is already bound or the socket is closed. IllegalArgumentException - if bindpoint is a SocketAddress subclass not supported by this socket Since: 1.4 See Also:

    • isBound()

  • getInetAddress

    public InetAddress getInetAddress()

    Returns the address to which the socket is connected.

    If the socket was connected prior to being closed, then this method will continue to return the connected address after the socket is closed.

    Returns: the remote IP address to which this socket is connected, or null if the socket is not connected.

  • getLocalAddress

    public InetAddress getLocalAddress()

    Gets the local address to which the socket is bound.

    Returns: the local address to which the socket is bound, or the wildcard address if the socket is closed or not bound yet. Since: 1.1

  • getPort

    public int getPort()

    Returns the remote port number to which this socket is connected.

    If the socket was connected prior to being closed, then this method will continue to return the connected port number after the socket is closed.

    Returns: the remote port number to which this socket is connected, or 0 if the socket is not connected yet.

  • getLocalPort

    public int getLocalPort()

    Returns the local port number to which this socket is bound.

    If the socket was bound prior to being closed, then this method will continue to return the local port number after the socket is closed.

    Returns: the local port number to which this socket is bound or -1 if the socket is not bound yet.

  • getRemoteSocketAddress

    public SocketAddress getRemoteSocketAddress()

    Returns the address of the endpoint this socket is connected to, or null if it is unconnected.

    If the socket was connected prior to being closed, then this method will continue to return the connected address after the socket is closed.

    Returns: a SocketAddress representing the remote endpoint of this socket, or null if it is not connected yet. Since: 1.4 See Also:

    • getInetAddress()
    • getPort()
    • connect(SocketAddress, int)
    • connect(SocketAddress)

  • getLocalSocketAddress

    public SocketAddress getLocalSocketAddress()

    Returns the address of the endpoint this socket is bound to.

    If a socket bound to an endpoint represented by an InetSocketAddress is closed, then this method will continue to return an InetSocketAddress after the socket is closed. In that case the returned InetSocketAddress's address is the wildcard address and its port is the local port that it was bound to.

    Returns: a SocketAddress representing the local endpoint of this socket, or null if the socket is not bound yet. Since: 1.4 See Also:

    • getLocalAddress()
    • getLocalPort()
    • bind(SocketAddress)

  • getChannel

    public SocketChannel getChannel()

    Returns the unique SocketChannel object associated with this socket, if any.

    A socket will have a channel if, and only if, the channel itself was created via the SocketChannel.open or ServerSocketChannel.accept methods.

    Returns: the socket channel associated with this socket, or null if this socket was not created for a channel Since: 1.4

  • getInputStream

    public InputStream getInputStream() throws IOException

    Returns an input stream for this socket.

    If this socket has an associated channel then the resulting input stream delegates all of its operations to the channel. If the channel is in non-blocking mode then the input stream's read operations will throw an IllegalBlockingModeException.

    Reading from the input stream is interruptible in the following circumstances:

    1. The socket is associated with a SocketChannel. In that case, interrupting a thread reading from the input stream will close the underlying channel and cause the read method to throw ClosedByInterruptException with the thread's interrupted status set.
    2. The socket uses the system-default socket implementation and a virtual thread is reading from the input stream. In that case, interrupting the virtual thread will cause it to wakeup and close the socket. The read method will then throw SocketException with the thread's interrupted status set.

    Under abnormal conditions the underlying connection may be broken by the remote host or the network software (for example a connection reset in the case of TCP connections). When a broken connection is detected by the network software the following applies to the returned input stream :-

    • The network software may discard bytes that are buffered by the socket. Bytes that aren't discarded by the network software can be read using read.

    • If there are no bytes buffered on the socket, or all buffered bytes have been consumed by read, then all subsequent calls to read will throw an IOException.

    • If there are no bytes buffered on the socket, and the socket has not been closed using close, then available will return 0.

    Closing the returned InputStream will close the associated socket.

    Returns: an input stream for reading bytes from this socket. Throws: IOException - if an I/O error occurs when creating the input stream, the socket is closed, the socket is not connected, or the socket input has been shutdown using shutdownInput()

  • getOutputStream

    public OutputStream getOutputStream() throws IOException

    Returns an output stream for this socket.

    If this socket has an associated channel then the resulting output stream delegates all of its operations to the channel. If the channel is in non-blocking mode then the output stream's write operations will throw an IllegalBlockingModeException.

    Writing to the output stream is interruptible in the following circumstances:

    1. The socket is associated with a SocketChannel. In that case, interrupting a thread writing to the output stream will close the underlying channel and cause the write method to throw ClosedByInterruptException with the thread's interrupted status set.
    2. The socket uses the system-default socket implementation and a virtual thread is writing to the output stream. In that case, interrupting the virtual thread will cause it to wakeup and close the socket. The write method will then throw SocketException with the thread's interrupted status set.

    Closing the returned OutputStream will close the associated socket.

    Returns: an output stream for writing bytes to this socket. Throws: IOException - if an I/O error occurs when creating the output stream, the socket is not connected or the socket is closed.

  • setTcpNoDelay

    public void setTcpNoDelay(boolean on) throws SocketException

    Enable/disable TCP_NODELAY (disable/enable Nagle's algorithm).

    Parameters: on - true to enable TCP_NODELAY, false to disable. Throws: SocketException - if there is an error in the underlying protocol, such as a TCP error, or the socket is closed. Since: 1.1 See Also:

    • getTcpNoDelay()

  • getTcpNoDelay

    public boolean getTcpNoDelay() throws SocketException

    Tests if TCP_NODELAY is enabled.

    Returns: a boolean indicating whether or not TCP_NODELAY is enabled. Throws: SocketException - if there is an error in the underlying protocol, such as a TCP error, or the socket is closed. Since: 1.1 See Also:

    • setTcpNoDelay(boolean)

  • setSoLinger

    public void setSoLinger(boolean on, int linger) throws SocketException

    Enable/disable SO_LINGER with the specified linger time in seconds. The maximum timeout value is platform specific. The setting only affects socket close.

    Parameters: on - whether or not to linger on. linger - how long to linger for, if on is true. Throws: SocketException - if there is an error in the underlying protocol, such as a TCP error, or the socket is closed. IllegalArgumentException - if the linger value is negative. Since: 1.1 See Also:

    • getSoLinger()

  • getSoLinger

    public int getSoLinger() throws SocketException

    Returns setting for SO_LINGER. -1 returns implies that the option is disabled. The setting only affects socket close.

    Returns: the setting for SO_LINGER. Throws: SocketException - if there is an error in the underlying protocol, such as a TCP error, or the socket is closed. Since: 1.1 See Also:

    • setSoLinger(boolean, int)

  • sendUrgentData

    public void sendUrgentData(int data) throws IOException

    Send one byte of urgent data on the socket. The byte to be sent is the lowest eight bits of the data parameter. The urgent byte is sent after any preceding writes to the socket OutputStream and before any future writes to the OutputStream.

    Parameters: data - The byte of data to send Throws: IOException - if there is an error sending the data. Since: 1.4

  • setOOBInline

    public void setOOBInline(boolean on) throws SocketException

    Enable/disable SO_OOBINLINE (receipt of TCP urgent data) By default, this option is disabled and TCP urgent data received on a socket is silently discarded. If the user wishes to receive urgent data, then this option must be enabled. When enabled, urgent data is received inline with normal data.

    Note, only limited support is provided for handling incoming urgent data. In particular, no notification of incoming urgent data is provided and there is no capability to distinguish between normal data and urgent data unless provided by a higher level protocol.

    Parameters: on - true to enable SO_OOBINLINE, false to disable. Throws: SocketException - if there is an error in the underlying protocol, such as a TCP error, or the socket is closed. Since: 1.4 See Also:

    • getOOBInline()

  • getOOBInline

    public boolean getOOBInline() throws SocketException

    Tests if SO_OOBINLINE is enabled.

    Returns: a boolean indicating whether or not SO_OOBINLINE is enabled. Throws: SocketException - if there is an error in the underlying protocol, such as a TCP error, or the socket is closed. Since: 1.4 See Also:

    • setOOBInline(boolean)

  • setSoTimeout

    public void setSoTimeout(int timeout) throws SocketException

    Enable/disable SO_TIMEOUT with the specified timeout, in milliseconds. With this option set to a positive timeout value, a read() call on the InputStream associated with this Socket will block for only this amount of time. If the timeout expires, a java.net.SocketTimeoutException is raised, though the Socket is still valid. A timeout of zero is interpreted as an infinite timeout. The option must be enabled prior to entering the blocking operation to have effect.

    Parameters: timeout - the specified timeout, in milliseconds. Throws: SocketException - if there is an error in the underlying protocol, such as a TCP error, or the socket is closed. IllegalArgumentException - if timeout is negative Since: 1.1 See Also:

    • getSoTimeout()

  • getSoTimeout

    public int getSoTimeout() throws SocketException

    Returns setting for SO_TIMEOUT. 0 returns implies that the option is disabled (i.e., timeout of infinity).

    Returns: the setting for SO_TIMEOUT Throws: SocketException - if there is an error in the underlying protocol, such as a TCP error, or the socket is closed. Since: 1.1 See Also:

    • setSoTimeout(int)

  • setSendBufferSize

    public void setSendBufferSize(int size) throws SocketException

    Sets the SO_SNDBUF option to the specified value for this Socket. The SO_SNDBUF option is used by the platform's networking code as a hint for the size to set the underlying network I/O buffers.

    Because SO_SNDBUF is a hint, applications that want to verify what size the buffers were set to should call getSendBufferSize().

    Parameters: size - the size to which to set the send buffer size. This value must be greater than 0. Throws: SocketException - if there is an error in the underlying protocol, such as a TCP error, or the socket is closed. IllegalArgumentException - if the value is 0 or is negative. Since: 1.2 See Also:

    • getSendBufferSize()

  • getSendBufferSize

    public int getSendBufferSize() throws SocketException

    Get value of the SO_SNDBUF option for this Socket, that is the buffer size used by the platform for output on this Socket.

    Returns: the value of the SO_SNDBUF option for this Socket. Throws: SocketException - if there is an error in the underlying protocol, such as a TCP error, or the socket is closed. Since: 1.2 See Also:

    • setSendBufferSize(int)

  • setReceiveBufferSize

    public void setReceiveBufferSize(int size) throws SocketException

    Sets the SO_RCVBUF option to the specified value for this Socket. The SO_RCVBUF option is used by the platform's networking code as a hint for the size to set the underlying network I/O buffers.

    Increasing the receive buffer size can increase the performance of network I/O for high-volume connection, while decreasing it can help reduce the backlog of incoming data.

    Because SO_RCVBUF is a hint, applications that want to verify what size the buffers were set to should call getReceiveBufferSize().

    The value of SO_RCVBUF is also used to set the TCP receive window that is advertised to the remote peer. Generally, the window size can be modified at any time when a socket is connected. However, if a receive window larger than 64K is required then this must be requested before the socket is connected to the remote peer. There are two cases to be aware of:

    1. For sockets accepted from a ServerSocket, this must be done by calling ServerSocket.setReceiveBufferSize(int) before the ServerSocket is bound to a local address.
    2. For client sockets, setReceiveBufferSize() must be called before connecting the socket to its remote peer.

    Parameters: size - the size to which to set the receive buffer size. This value must be greater than 0. Throws: IllegalArgumentException - if the value is 0 or is negative. SocketException - if there is an error in the underlying protocol, such as a TCP error, or the socket is closed. Since: 1.2 See Also:

    • getReceiveBufferSize()
    • ServerSocket.setReceiveBufferSize(int)

  • getReceiveBufferSize

    public int getReceiveBufferSize() throws SocketException

    Gets the value of the SO_RCVBUF option for this Socket, that is the buffer size used by the platform for input on this Socket.

    Returns: the value of the SO_RCVBUF option for this Socket. Throws: SocketException - if there is an error in the underlying protocol, such as a TCP error, or the socket is closed. Since: 1.2 See Also:

    • setReceiveBufferSize(int)

  • setKeepAlive

    public void setKeepAlive(boolean on) throws SocketException

    Enable/disable SO_KEEPALIVE.

    Parameters: on - whether or not to have socket keep alive turned on. Throws: SocketException - if there is an error in the underlying protocol, such as a TCP error, or the socket is closed. Since: 1.3 See Also:

    • getKeepAlive()

  • getKeepAlive

    public boolean getKeepAlive() throws SocketException

    Tests if SO_KEEPALIVE is enabled.

    Returns: a boolean indicating whether or not SO_KEEPALIVE is enabled. Throws: SocketException - if there is an error in the underlying protocol, such as a TCP error, or the socket is closed. Since: 1.3 See Also:

    • setKeepAlive(boolean)

  • setTrafficClass

    public void setTrafficClass(int tc) throws SocketException

    Sets traffic class or type-of-service octet in the IP header for packets sent from this Socket. As the underlying network implementation may ignore this value applications should consider it a hint.

    The tc must be in the range 0 <= tc <= 255 or an IllegalArgumentException will be thrown.

    Notes:

    For Internet Protocol v4 the value consists of an integer, the least significant 8 bits of which represent the value of the TOS octet in IP packets sent by the socket. RFC 1349 defines the TOS values as follows:

    • IPTOS_LOWCOST (0x02)
    • IPTOS_RELIABILITY (0x04)
    • IPTOS_THROUGHPUT (0x08)
    • IPTOS_LOWDELAY (0x10)

    The last low order bit is always ignored as this corresponds to the MBZ (must be zero) bit.

    Setting bits in the precedence field may result in a SocketException indicating that the operation is not permitted.

    As RFC 1122 section 4.2.4.2 indicates, a compliant TCP implementation should, but is not required to, let application change the TOS field during the lifetime of a connection. So whether the type-of-service field can be changed after the TCP connection has been established depends on the implementation in the underlying platform. Applications should not assume that they can change the TOS field after the connection.

    For Internet Protocol v6 tc is the value that would be placed into the sin6_flowinfo field of the IP header.

    Parameters: tc - an int value for the bitset. Throws: SocketException - if there is an error setting the traffic class or type-of-service, or the socket is closed. Since: 1.4 See Also:

    • getTrafficClass()
    • StandardSocketOptions.IP_TOS

  • getTrafficClass

    public int getTrafficClass() throws SocketException

    Gets traffic class or type-of-service in the IP header for packets sent from this Socket

    As the underlying network implementation may ignore the traffic class or type-of-service set using setTrafficClass(int) this method may return a different value than was previously set using the setTrafficClass(int) method on this Socket.

    Returns: the traffic class or type-of-service already set Throws: SocketException - if there is an error obtaining the traffic class or type-of-service value, or the socket is closed. Since: 1.4 See Also:

    • setTrafficClass(int)
    • StandardSocketOptions.IP_TOS

  • setReuseAddress

    public void setReuseAddress(boolean on) throws SocketException

    Enable/disable the SO_REUSEADDR socket option.

    When a TCP connection is closed the connection may remain in a timeout state for a period of time after the connection is closed (typically known as the TIME_WAIT state or 2MSL wait state). For applications using a well known socket address or port it may not be possible to bind a socket to the required SocketAddress if there is a connection in the timeout state involving the socket address or port.

    Enabling SO_REUSEADDR prior to binding the socket using bind(SocketAddress) allows the socket to be bound even though a previous connection is in a timeout state.

    When a Socket is created the initial setting of SO_REUSEADDR is disabled.

    The behaviour when SO_REUSEADDR is enabled or disabled after a socket is bound (See isBound()) is not defined.

    Parameters: on - whether to enable or disable the socket option Throws: SocketException - if an error occurs enabling or disabling the SO_REUSEADDR socket option, or the socket is closed. Since: 1.4 See Also:

    • getReuseAddress()
    • bind(SocketAddress)
    • isClosed()
    • isBound()

  • getReuseAddress

    public boolean getReuseAddress() throws SocketException

    Tests if SO_REUSEADDR is enabled.

    Returns: a boolean indicating whether or not SO_REUSEADDR is enabled. Throws: SocketException - if there is an error in the underlying protocol, such as a TCP error, or the socket is closed. Since: 1.4 See Also:

    • setReuseAddress(boolean)

  • close

    public void close() throws IOException

    Closes this socket.

    Any thread currently blocked in an I/O operation upon this socket will throw a SocketException.

    Once a socket has been closed, it is not available for further networking use (i.e. can't be reconnected or rebound) and several of the methods defined by this class will throw an exception if invoked on the closed socket. A new socket needs to be created.

    Closing this socket will also close the socket's InputStream and OutputStream.

    If this socket has an associated channel then the channel is closed as well.

    Specified by: close in interface AutoCloseable Specified by: close in interface Closeable Throws: IOException - if an I/O error occurs when closing this socket. See Also:

    • isClosed()

  • shutdownInput

    public void shutdownInput() throws IOException

    Places the input stream for this socket at "end of stream". Any data sent to the input stream side of the socket is acknowledged and then silently discarded.

    If you read from a socket input stream after invoking this method on the socket, the stream's available method will return 0, and its read methods will return -1 (end of stream).

    Throws: IOException - if an I/O error occurs when shutting down this socket, the socket is not connected or the socket is closed. Since: 1.3 See Also:

    • shutdownOutput()
    • close()
    • setSoLinger(boolean, int)
    • isInputShutdown()

  • shutdownOutput

    public void shutdownOutput() throws IOException

    Disables the output stream for this socket. For a TCP socket, any previously written data will be sent followed by TCP's normal connection termination sequence. If you write to a socket output stream after invoking shutdownOutput() on the socket, the stream will throw an IOException.

    Throws: IOException - if an I/O error occurs when shutting down this socket, the socket is not connected or the socket is closed. Since: 1.3 See Also:

    • shutdownInput()
    • close()
    • setSoLinger(boolean, int)
    • isOutputShutdown()

  • toString

    public String toString()

    Converts this socket to a String.

    Overrides: toString in class Object Returns: a string representation of this socket.

  • isConnected

    public boolean isConnected()

    Returns the connection state of the socket.

    Note: Closing a socket doesn't clear its connection state, which means this method will return true for a closed socket (see isClosed()) if it was successfully connected prior to being closed.

    Returns: true if the socket was successfully connected to a server Since: 1.4

  • isBound

    public boolean isBound()

    Returns the binding state of the socket.

    Note: Closing a socket doesn't clear its binding state, which means this method will return true for a closed socket (see isClosed()) if it was successfully bound prior to being closed.

    Returns: true if the socket was successfully bound to an address Since: 1.4 See Also:

    • bind(SocketAddress)

  • isClosed

    public boolean isClosed()

    Returns the closed state of the socket.

    Returns: true if the socket has been closed Since: 1.4 See Also:

    • close()

  • isInputShutdown

    public boolean isInputShutdown()

    Returns whether the read-half of the socket connection is closed.

    Returns: true if the input of the socket has been shutdown Since: 1.4 See Also:

    • shutdownInput()

  • isOutputShutdown

    public boolean isOutputShutdown()

    Returns whether the write-half of the socket connection is closed.

    Returns: true if the output of the socket has been shutdown Since: 1.4 See Also:

    • shutdownOutput()

  • setSocketImplFactory

    @Deprecated(since="17") public static void setSocketImplFactory(SocketImplFactory fac) throws IOException

    Deprecated.

    Use a SocketFactory and subclass Socket directly.
    This method provided a way in early JDK releases to replace the system wide implementation of Socket. It has been mostly obsolete since Java 1.4. If required, a Socket can be created to use a custom implementation by extending Socket and using the protected constructor that takes an implementation as a parameter.

    Sets the client socket implementation factory for the application. The factory can be specified only once.

    When an application creates a new client socket, the socket implementation factory's createSocketImpl method is called to create the actual socket implementation.

    Passing null to the method is a no-op unless the factory was already set.

    Parameters: fac - the desired factory. Throws: IOException - if an I/O error occurs when setting the socket factory. SocketException - if the factory is already defined. See Also:

    • SocketImplFactory.createSocketImpl()

  • setPerformancePreferences

    @Deprecated(since="26", forRemoval=true) public void setPerformancePreferences(int connectionTime, int latency, int bandwidth)

    Deprecated, for removal: This API element is subject to removal in a future version.

    This method was intended to allow for protocols that are now obsolete.

    Sets performance preferences for this socket.

    Sockets use the TCP/IP protocol by default. Some implementations may offer alternative protocols which have different performance characteristics than TCP/IP. This method allows the application to express its own preferences as to how these tradeoffs should be made when the implementation chooses from the available protocols.

    Performance preferences are described by three integers whose values indicate the relative importance of short connection time, low latency, and high bandwidth. The absolute values of the integers are irrelevant; in order to choose a protocol the values are simply compared, with larger values indicating stronger preferences. Negative values represent a lower priority than positive values. If the application prefers short connection time over both low latency and high bandwidth, for example, then it could invoke this method with the values (1, 0, 0). If the application prefers high bandwidth above low latency, and low latency above short connection time, then it could invoke this method with the values (0, 1, 2).

    Invoking this method after this socket has been connected will have no effect.

    Parameters: connectionTime - An int expressing the relative importance of a short connection time latency - An int expressing the relative importance of low latency bandwidth - An int expressing the relative importance of high bandwidth Since: 1.5

  • setOption

    public <T> Socket setOption(SocketOption<T> name, T value) throws IOException

    Sets the value of a socket option.

    Type Parameters: T - The type of the socket option value Parameters: name - The socket option value - The value of the socket option. A value of null may be valid for some options. Returns: this Socket Throws: UnsupportedOperationException - if the socket does not support the option. IllegalArgumentException - if the value is not valid for the option. IOException - if an I/O error occurs, or if the socket is closed. NullPointerException - if name is null Since: 9

  • getOption

    public <T> T getOption(SocketOption<T> name) throws IOException

    Returns the value of a socket option.

    Type Parameters: T - The type of the socket option value Parameters: name - The socket option Returns: The value of the socket option. Throws: UnsupportedOperationException - if the socket does not support the option. IOException - if an I/O error occurs, or if the socket is closed. NullPointerException - if name is null Since: 9

  • supportedOptions

    public Set<SocketOption<?>> supportedOptions()

    Returns a set of the socket options supported by this socket. This method will continue to return the set of options even after the socket has been closed.

    Returns: A set of the socket options supported by this socket. This set may be empty if the socket's SocketImpl cannot be created. Since: 9

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