Added in API level 1

DatagramChannel

abstract class DatagramChannel : AbstractSelectableChannel, ByteChannel, GatheringByteChannel, MulticastChannel, ScatteringByteChannel

kotlin.Any
↳	java.nio.channels.spi.AbstractInterruptibleChannel
	↳	java.nio.channels.SelectableChannel
		↳	java.nio.channels.spi.AbstractSelectableChannel
			↳	java.nio.channels.DatagramChannel

A selectable channel for datagram-oriented sockets.

A datagram channel is created by invoking one of the #open methods of this class. It is not possible to create a channel for an arbitrary, pre-existing datagram socket. A newly-created datagram channel is open but not connected. A datagram channel need not be connected in order for the send and receive methods to be used. A datagram channel may be connected, by invoking its connect method, in order to avoid the overhead of the security checks are otherwise performed as part of every send and receive operation. A datagram channel must be connected in order to use the read and write methods, since those methods do not accept or return socket addresses.

Once connected, a datagram channel remains connected until it is disconnected or closed. Whether or not a datagram channel is connected may be determined by invoking its isConnected method.

Socket options are configured using the setOption method. A datagram channel to an Internet Protocol socket supports the following options:

Socket options

Option Name	Description
SO_SNDBUF	The size of the socket send buffer
SO_RCVBUF	The size of the socket receive buffer
SO_REUSEADDR	Re-use address
SO_BROADCAST	Allow transmission of broadcast datagrams
IP_TOS	The Type of Service (ToS) octet in the Internet Protocol (IP) header
IP_MULTICAST_IF	The network interface for Internet Protocol (IP) multicast datagrams
IP_MULTICAST_TTL	The time-to-live for Internet Protocol (IP) multicast datagrams
IP_MULTICAST_LOOP	Loopback for Internet Protocol (IP) multicast datagrams

Additional (implementation specific) options may also be supported.

Datagram channels are safe for use by multiple concurrent threads. They support concurrent reading and writing, though at most one thread may be reading and at most one thread may be writing at any given time.

Summary

Protected constructors
DatagramChannel(provider: SelectorProvider!) Initializes a new instance of this class.

Public methods
abstract DatagramChannel!	bind(local: SocketAddress!)
abstract DatagramChannel!	connect(remote: SocketAddress!) Connects this channel's socket.
abstract DatagramChannel!	disconnect() Disconnects this channel's socket.
abstract SocketAddress!	getLocalAddress() Returns the socket address that this channel's socket is bound to.
abstract SocketAddress!	getRemoteAddress() Returns the remote address to which this channel's socket is connected.
abstract Boolean	isConnected() Tells whether or not this channel's socket is connected.
open static DatagramChannel!	open() Opens a datagram channel.
open static DatagramChannel!	open(family: ProtocolFamily!) Opens a datagram channel.
abstract Int	read(dst: ByteBuffer!) Reads a datagram from this channel.
Long	read(dsts: Array<ByteBuffer!>!) Reads a datagram from this channel.
abstract Long	read(dsts: Array<ByteBuffer!>!, offset: Int, length: Int) Reads a datagram from this channel.
abstract SocketAddress!	receive(dst: ByteBuffer!) Receives a datagram via this channel.
abstract Int	send(src: ByteBuffer!, target: SocketAddress!) Sends a datagram via this channel.
abstract DatagramChannel!	setOption(name: SocketOption<T>!, value: T)
abstract DatagramSocket!	socket() Retrieves a datagram socket associated with this channel.
Int	validOps() Returns an operation set identifying this channel's supported operations.
abstract Int	write(src: ByteBuffer!) Writes a datagram to this channel.
Long	write(srcs: Array<ByteBuffer!>!) Writes a datagram to this channel.
abstract Long	write(srcs: Array<ByteBuffer!>!, offset: Int, length: Int) Writes a datagram to this channel.

Inherited functions
From class AbstractInterruptibleChannel Unit begin() Marks the beginning of an I/O operation that might block indefinitely. This method should be invoked in tandem with the end method, using a try ... finally block as shown above, in order to implement asynchronous closing and interruption for this channel. Unit close() Closes this channel. If the channel has already been closed then this method returns immediately. Otherwise it marks the channel as closed and then invokes the implCloseChannel method in order to complete the close operation. Unit end(completed: Boolean) Marks the end of an I/O operation that might block indefinitely. This method should be invoked in tandem with the begin method, using a try ... finally block as shown above, in order to implement asynchronous closing and interruption for this channel. Unit implCloseChannel() Closes this channel. This method is invoked by the #close method in order to perform the actual work of closing the channel. This method is only invoked if the channel has not yet been closed, and it is never invoked more than once. An implementation of this method must arrange for any other thread that is blocked in an I/O operation upon this channel to return immediately, either by throwing an exception or by returning normally. Boolean isOpen()
From class NetworkChannel NetworkChannel! bind(local: SocketAddress!) Binds the channel's socket to a local address. This method is used to establish an association between the socket and a local address. Once an association is established then the socket remains bound until the channel is closed. If the local parameter has the value null then the socket will be bound to an address that is assigned automatically. SocketAddress! getLocalAddress() Returns the socket address that this channel's socket is bound to. Where the channel is bound to an Internet Protocol socket address then the return value from this method is of type . T getOption(name: SocketOption<T>!) Returns the value of a socket option. NetworkChannel! setOption(name: SocketOption<T>!, value: T) Sets the value of a socket option. MutableSet<SocketOption<*>!>! supportedOptions() Returns a set of the socket options supported by this channel. This method will continue to return the set of options even after the channel has been closed.
From class AbstractSelectableChannel Any! blockingLock() SelectableChannel! configureBlocking(block: Boolean) Adjusts this channel's blocking mode. If the given blocking mode is different from the current blocking mode then this method invokes the implConfigureBlocking method, while holding the appropriate locks, in order to change the mode. Unit implCloseChannel() Closes this channel. This method, which is specified in the AbstractInterruptibleChannel class and is invoked by the java.nio.channels.Channel#close method, in turn invokes the implCloseSelectableChannel method in order to perform the actual work of closing this channel. It then cancels all of this channel's keys. Unit implCloseSelectableChannel() Closes this selectable channel. This method is invoked by the java.nio.channels.Channel#close method in order to perform the actual work of closing the channel. This method is only invoked if the channel has not yet been closed, and it is never invoked more than once. An implementation of this method must arrange for any other thread that is blocked in an I/O operation upon this channel to return immediately, either by throwing an exception or by returning normally. Unit implConfigureBlocking(block: Boolean) Adjusts this channel's blocking mode. This method is invoked by the configureBlocking method in order to perform the actual work of changing the blocking mode. This method is only invoked if the new mode is different from the current mode. Boolean isBlocking() Boolean isRegistered() SelectionKey! keyFor(sel: Selector!) SelectorProvider! provider() Returns the provider that created this channel. SelectionKey! register(sel: Selector!, ops: Int, att: Any!) Registers this channel with the given selector, returning a selection key. This method first verifies that this channel is open and that the given initial interest set is valid. If this channel is already registered with the given selector then the selection key representing that registration is returned after setting its interest set to the given value. Otherwise this channel has not yet been registered with the given selector, so the register method of the selector is invoked while holding the appropriate locks. The resulting key is added to this channel's key set before being returned.
From class Channel Unit close() Closes this channel. After a channel is closed, any further attempt to invoke I/O operations upon it will cause a ClosedChannelException to be thrown. If this channel is already closed then invoking this method has no effect. This method may be invoked at any time. If some other thread has already invoked it, however, then another invocation will block until the first invocation is complete, after which it will return without effect. Boolean isOpen() Tells whether or not this channel is open.
From class MulticastChannel MembershipKey! join(group: InetAddress!, interf: NetworkInterface!) Joins a multicast group to begin receiving all datagrams sent to the group, returning a membership key. If this channel is currently a member of the group on the given interface to receive all datagrams then the membership key, representing that membership, is returned. Otherwise this channel joins the group and the resulting new membership key is returned. The resulting membership key is not source-specific. A multicast channel may join several multicast groups, including the same group on more than one interface. An implementation may impose a limit on the number of groups that may be joined at the same time. MembershipKey! join(group: InetAddress!, interf: NetworkInterface!, source: InetAddress!) Joins a multicast group to begin receiving datagrams sent to the group from a given source address. If this channel is currently a member of the group on the given interface to receive datagrams from the given source address then the membership key, representing that membership, is returned. Otherwise this channel joins the group and the resulting new membership key is returned. The resulting membership key is source-specific. Membership is cumulative and this method may be invoked again with the same group and interface to allow receiving datagrams sent by other source addresses to the group.
From class SelectableChannel SelectionKey! register(sel: Selector!, ops: Int) Registers this channel with the given selector, returning a selection key. An invocation of this convenience method of the form sc.register(sel, ops) behaves in exactly the same way as the invocation sc. register(sel, ops, null) Int validOps() Returns an operation set identifying this channel's supported operations. The bits that are set in this integer value denote exactly the operations that are valid for this channel. This method always returns the same value for a given concrete channel class.

Protected constructors

DatagramChannel

Added in API level 1

protected DatagramChannel(provider: SelectorProvider!)

Initializes a new instance of this class.

Parameters
provider	SelectorProvider!: The provider that created this channel

Public methods

bind

Added in API level 24

abstract fun bind(local: SocketAddress!): DatagramChannel!

Parameters
local	SocketAddress!: The address to bind the socket, or null to bind the socket to an automatically assigned socket address

Return
DatagramChannel!	This channel

Exceptions
java.nio.channels.AlreadyBoundException	If the socket is already bound
java.nio.channels.UnsupportedAddressTypeException	If the type of the given address is not supported
java.nio.channels.ClosedChannelException	If the channel is closed
java.io.IOException	If some other I/O error occurs
java.lang.SecurityException	If a security manager has been installed and its checkListen method denies the operation

connect

Added in API level 1

abstract fun connect(remote: SocketAddress!): DatagramChannel!

Connects this channel's socket.

The channel's socket is configured so that it only receives datagrams from, and sends datagrams to, the given remote peer address. Once connected, datagrams may not be received from or sent to any other address. A datagram socket remains connected until it is explicitly disconnected or until it is closed.

This method performs exactly the same security checks as the java.net.DatagramSocket#connect method of the class. That is, if a security manager has been installed then this method verifies that its checkAccept and java.lang.SecurityManager#checkConnect methods permit datagrams to be received from and sent to, respectively, the given remote address.

This method may be invoked at any time. It will not have any effect on read or write operations that are already in progress at the moment that it is invoked. If this channel's socket is not bound then this method will first cause the socket to be bound to an address that is assigned automatically, as if invoking the bind method with a parameter of null.

Parameters
remote	SocketAddress!: The remote address to which this channel is to be connected

Return
DatagramChannel!	This datagram channel

Exceptions
java.nio.channels.AlreadyConnectedException	If this channel is already connected
java.nio.channels.ClosedChannelException	If this channel is closed
java.nio.channels.AsynchronousCloseException	If another thread closes this channel while the connect operation is in progress
java.nio.channels.ClosedByInterruptException	If another thread interrupts the current thread while the connect operation is in progress, thereby closing the channel and setting the current thread's interrupt status
java.nio.channels.UnresolvedAddressException	If the given remote address is not fully resolved
java.nio.channels.UnsupportedAddressTypeException	If the type of the given remote address is not supported
java.lang.SecurityException	If a security manager has been installed and it does not permit access to the given remote address
java.io.IOException	If some other I/O error occurs

disconnect

Added in API level 1

abstract fun disconnect(): DatagramChannel!

Disconnects this channel's socket.

The channel's socket is configured so that it can receive datagrams from, and sends datagrams to, any remote address so long as the security manager, if installed, permits it.

This method may be invoked at any time. It will not have any effect on read or write operations that are already in progress at the moment that it is invoked.

If this channel's socket is not connected, or if the channel is closed, then invoking this method has no effect.

Return
DatagramChannel!	This datagram channel

Exceptions
java.io.IOException	If some other I/O error occurs

getLocalAddress

Added in API level 24

abstract fun getLocalAddress(): SocketAddress!

Returns the socket address that this channel's socket is bound to.

Where the channel is bound to an Internet Protocol socket address then the return value from this method is of type .

If there is a security manager set, its checkConnect method is called with the local address and -1 as its arguments to see if the operation is allowed. If the operation is not allowed, a SocketAddress representing the loopback address and the local port of the channel's socket is returned.

Return
SocketAddress!	The SocketAddress that the socket is bound to, or the SocketAddress representing the loopback address if denied by the security manager, or null if the channel's socket is not bound

Exceptions
java.nio.channels.ClosedChannelException	If the channel is closed
java.io.IOException	If an I/O error occurs

getRemoteAddress

Added in API level 24

abstract fun getRemoteAddress(): SocketAddress!

Returns the remote address to which this channel's socket is connected.

Return
SocketAddress!	The remote address; null if the channel's socket is not connected

Exceptions
java.nio.channels.ClosedChannelException	If the channel is closed
java.io.IOException	If an I/O error occurs

isConnected

Added in API level 1

abstract fun isConnected(): Boolean

Tells whether or not this channel's socket is connected.

Return
Boolean	true if, and only if, this channel's socket is open and connected

open

Added in API level 1

open static fun open(): DatagramChannel!

Opens a datagram channel.

The new channel is created by invoking the openDatagramChannel method of the system-wide default object. The channel will not be connected.

The ProtocolFamily of the channel's socket is platform (and possibly configuration) dependent and therefore unspecified. The open allows the protocol family to be selected when opening a datagram channel, and should be used to open datagram channels that are intended for Internet Protocol multicasting.

Return
DatagramChannel!	A new datagram channel

Exceptions
java.io.IOException	If an I/O error occurs

open

Added in API level 24

open static fun open(family: ProtocolFamily!): DatagramChannel!

Opens a datagram channel.

The family parameter is used to specify the ProtocolFamily. If the datagram channel is to be used for IP multicasting then this should correspond to the address type of the multicast groups that this channel will join.

The new channel is created by invoking the openDatagramChannel method of the system-wide default object. The channel will not be connected.

Parameters
family	ProtocolFamily!: The protocol family

Return
DatagramChannel!	A new datagram channel

Exceptions
java.lang.UnsupportedOperationException	If the specified protocol family is not supported. For example, suppose the parameter is specified as StandardProtocolFamily.INET6 but IPv6 is not enabled on the platform.
java.io.IOException	If an I/O error occurs

read

Added in API level 1

abstract fun read(dst: ByteBuffer!): Int

Reads a datagram from this channel.

This method may only be invoked if this channel's socket is connected, and it only accepts datagrams from the socket's peer. If there are more bytes in the datagram than remain in the given buffer then the remainder of the datagram is silently discarded. Otherwise this method behaves exactly as specified in the ReadableByteChannel interface.

Parameters
dst	ByteBuffer!: The buffer into which bytes are to be transferred

Return
Int	The number of bytes read, possibly zero, or -1 if the channel has reached end-of-stream

Exceptions
java.nio.channels.NonReadableChannelException	If this channel was not opened for reading
java.nio.channels.ClosedChannelException	If this channel is closed
java.nio.channels.AsynchronousCloseException	If another thread closes this channel while the read operation is in progress
java.nio.channels.ClosedByInterruptException	If another thread interrupts the current thread while the read operation is in progress, thereby closing the channel and setting the current thread's interrupt status
java.io.IOException	If some other I/O error occurs
java.nio.channels.NotYetConnectedException	If this channel's socket is not connected

read

Added in API level 1

fun read(dsts: Array<ByteBuffer!>!): Long

Reads a datagram from this channel.

This method may only be invoked if this channel's socket is connected, and it only accepts datagrams from the socket's peer. If there are more bytes in the datagram than remain in the given buffers then the remainder of the datagram is silently discarded. Otherwise this method behaves exactly as specified in the ScatteringByteChannel interface.

Parameters
dsts	Array<ByteBuffer!>!: The buffers into which bytes are to be transferred

Return
Long	The number of bytes read, possibly zero, or -1 if the channel has reached end-of-stream

Exceptions
java.nio.channels.NonReadableChannelException	If this channel was not opened for reading
java.nio.channels.ClosedChannelException	If this channel is closed
java.nio.channels.AsynchronousCloseException	If another thread closes this channel while the read operation is in progress
java.nio.channels.ClosedByInterruptException	If another thread interrupts the current thread while the read operation is in progress, thereby closing the channel and setting the current thread's interrupt status
java.io.IOException	If some other I/O error occurs
java.nio.channels.NotYetConnectedException	If this channel's socket is not connected

read

Added in API level 1

abstract fun read(
    dsts: Array<ByteBuffer!>!, 
    offset: Int, 
    length: Int
): Long

Reads a datagram from this channel.

This method may only be invoked if this channel's socket is connected, and it only accepts datagrams from the socket's peer. If there are more bytes in the datagram than remain in the given buffers then the remainder of the datagram is silently discarded. Otherwise this method behaves exactly as specified in the ScatteringByteChannel interface.

Parameters
dsts	Array<ByteBuffer!>!: The buffers into which bytes are to be transferred
offset	Int: The offset within the buffer array of the first buffer into which bytes are to be transferred; must be non-negative and no larger than dsts.length
length	Int: The maximum number of buffers to be accessed; must be non-negative and no larger than dsts.length - offset

Return
Long	The number of bytes read, possibly zero, or -1 if the channel has reached end-of-stream

Exceptions
java.lang.IndexOutOfBoundsException	If the preconditions on the offset and length parameters do not hold
java.nio.channels.NonReadableChannelException	If this channel was not opened for reading
java.nio.channels.ClosedChannelException	If this channel is closed
java.nio.channels.AsynchronousCloseException	If another thread closes this channel while the read operation is in progress
java.nio.channels.ClosedByInterruptException	If another thread interrupts the current thread while the read operation is in progress, thereby closing the channel and setting the current thread's interrupt status
java.io.IOException	If some other I/O error occurs
java.nio.channels.NotYetConnectedException	If this channel's socket is not connected

receive

Added in API level 1

abstract fun receive(dst: ByteBuffer!): SocketAddress!

Receives a datagram via this channel.

If a datagram is immediately available, or if this channel is in blocking mode and one eventually becomes available, then the datagram is copied into the given byte buffer and its source address is returned. If this channel is in non-blocking mode and a datagram is not immediately available then this method immediately returns null.

The datagram is transferred into the given byte buffer starting at its current position, as if by a regular read operation. If there are fewer bytes remaining in the buffer than are required to hold the datagram then the remainder of the datagram is silently discarded.

This method performs exactly the same security checks as the receive method of the class. That is, if the socket is not connected to a specific remote address and a security manager has been installed then for each datagram received this method verifies that the source's address and port number are permitted by the security manager's checkAccept method. The overhead of this security check can be avoided by first connecting the socket via the connect method.

This method may be invoked at any time. If another thread has already initiated a read operation upon this channel, however, then an invocation of this method will block until the first operation is complete. If this channel's socket is not bound then this method will first cause the socket to be bound to an address that is assigned automatically, as if invoking the bind method with a parameter of null.

Parameters
dst	ByteBuffer!: The buffer into which the datagram is to be transferred

Return
SocketAddress!	The datagram's source address, or null if this channel is in non-blocking mode and no datagram was immediately available

Exceptions
java.nio.channels.ClosedChannelException	If this channel is closed
java.nio.channels.AsynchronousCloseException	If another thread closes this channel while the read operation is in progress
java.nio.channels.ClosedByInterruptException	If another thread interrupts the current thread while the read operation is in progress, thereby closing the channel and setting the current thread's interrupt status
java.lang.SecurityException	If a security manager has been installed and it does not permit datagrams to be accepted from the datagram's sender
java.io.IOException	If some other I/O error occurs

send

Added in API level 1

abstract fun send(
    src: ByteBuffer!, 
    target: SocketAddress!
): Int

Sends a datagram via this channel.

If this channel is in non-blocking mode and there is sufficient room in the underlying output buffer, or if this channel is in blocking mode and sufficient room becomes available, then the remaining bytes in the given buffer are transmitted as a single datagram to the given target address.

The datagram is transferred from the byte buffer as if by a regular write operation.

This method performs exactly the same security checks as the send method of the class. That is, if the socket is not connected to a specific remote address and a security manager has been installed then for each datagram sent this method verifies that the target address and port number are permitted by the security manager's java.lang.SecurityManager#checkConnect method. The overhead of this security check can be avoided by first connecting the socket via the connect method.

This method may be invoked at any time. If another thread has already initiated a write operation upon this channel, however, then an invocation of this method will block until the first operation is complete. If this channel's socket is not bound then this method will first cause the socket to be bound to an address that is assigned automatically, as if by invoking the bind method with a parameter of null.

Parameters
src	ByteBuffer!: The buffer containing the datagram to be sent
target	SocketAddress!: The address to which the datagram is to be sent

Return
Int	The number of bytes sent, which will be either the number of bytes that were remaining in the source buffer when this method was invoked or, if this channel is non-blocking, may be zero if there was insufficient room for the datagram in the underlying output buffer

Exceptions
java.nio.channels.AlreadyConnectedException	If this channel is connected to a different address from that specified by target
java.nio.channels.ClosedChannelException	If this channel is closed
java.nio.channels.AsynchronousCloseException	If another thread closes this channel while the read operation is in progress
java.nio.channels.ClosedByInterruptException	If another thread interrupts the current thread while the read operation is in progress, thereby closing the channel and setting the current thread's interrupt status
java.nio.channels.UnresolvedAddressException	If the given remote address is not fully resolved
java.nio.channels.UnsupportedAddressTypeException	If the type of the given remote address is not supported
java.lang.SecurityException	If a security manager has been installed and it does not permit datagrams to be sent to the given address
java.io.IOException	If some other I/O error occurs

setOption

Added in API level 24

abstract fun <T : Any!> setOption(
    name: SocketOption<T>!, 
    value: T
): DatagramChannel!

Parameters
<T>	The type of the socket option value
name	SocketOption<T>!: The socket option
value	T: The value of the socket option. A value of null may be a valid value for some socket options.

Return
DatagramChannel!	This channel

Exceptions
java.lang.UnsupportedOperationException	If the socket option is not supported by this channel
java.lang.IllegalArgumentException	If the value is not a valid value for this socket option
java.nio.channels.ClosedChannelException	If this channel is closed
java.io.IOException	If an I/O error occurs

socket

Added in API level 1

abstract fun socket(): DatagramSocket!

Retrieves a datagram socket associated with this channel.

The returned object will not declare any public methods that are not declared in the java.net.DatagramSocket class.

Return
DatagramSocket!	A datagram socket associated with this channel

validOps

Added in API level 1

fun validOps(): Int

Returns an operation set identifying this channel's supported operations.

Datagram channels support reading and writing, so this method returns (SelectionKey.OP_READ | java.nio.channels.SelectionKey#OP_WRITE).

Return
Int	The valid-operation set

write

Added in API level 1

abstract fun write(src: ByteBuffer!): Int

Writes a datagram to this channel.

This method may only be invoked if this channel's socket is connected, in which case it sends datagrams directly to the socket's peer. Otherwise it behaves exactly as specified in the WritableByteChannel interface.

Parameters
src	ByteBuffer!: The buffer from which bytes are to be retrieved

Return
Int	The number of bytes written, possibly zero

Exceptions
java.nio.channels.NonWritableChannelException	If this channel was not opened for writing
java.nio.channels.ClosedChannelException	If this channel is closed
java.nio.channels.AsynchronousCloseException	If another thread closes this channel while the write operation is in progress
java.nio.channels.ClosedByInterruptException	If another thread interrupts the current thread while the write operation is in progress, thereby closing the channel and setting the current thread's interrupt status
java.io.IOException	If some other I/O error occurs
java.nio.channels.NotYetConnectedException	If this channel's socket is not connected

write

Added in API level 1

fun write(srcs: Array<ByteBuffer!>!): Long

Writes a datagram to this channel.

This method may only be invoked if this channel's socket is connected, in which case it sends datagrams directly to the socket's peer. Otherwise it behaves exactly as specified in the GatheringByteChannel interface.

Parameters
srcs	Array<ByteBuffer!>!: The buffers from which bytes are to be retrieved

Return
Long	The number of bytes sent, which will be either the number of bytes that were remaining in the source buffer when this method was invoked or, if this channel is non-blocking, may be zero if there was insufficient room for the datagram in the underlying output buffer

Exceptions
java.nio.channels.NonWritableChannelException	If this channel was not opened for writing
java.nio.channels.ClosedChannelException	If this channel is closed
java.nio.channels.AsynchronousCloseException	If another thread closes this channel while the write operation is in progress
java.nio.channels.ClosedByInterruptException	If another thread interrupts the current thread while the write operation is in progress, thereby closing the channel and setting the current thread's interrupt status
java.io.IOException	If some other I/O error occurs
java.nio.channels.NotYetConnectedException	If this channel's socket is not connected

write

Added in API level 1

abstract fun write(
    srcs: Array<ByteBuffer!>!, 
    offset: Int, 
    length: Int
): Long

Writes a datagram to this channel.

This method may only be invoked if this channel's socket is connected, in which case it sends datagrams directly to the socket's peer. Otherwise it behaves exactly as specified in the GatheringByteChannel interface.

Parameters
srcs	Array<ByteBuffer!>!: The buffers from which bytes are to be retrieved
offset	Int: The offset within the buffer array of the first buffer from which bytes are to be retrieved; must be non-negative and no larger than srcs.length
length	Int: The maximum number of buffers to be accessed; must be non-negative and no larger than srcs.length - offset

Return
Long	The number of bytes sent, which will be either the number of bytes that were remaining in the source buffer when this method was invoked or, if this channel is non-blocking, may be zero if there was insufficient room for the datagram in the underlying output buffer

Exceptions
java.lang.IndexOutOfBoundsException	If the preconditions on the offset and length parameters do not hold
java.nio.channels.NonWritableChannelException	If this channel was not opened for writing
java.nio.channels.ClosedChannelException	If this channel is closed
java.nio.channels.AsynchronousCloseException	If another thread closes this channel while the write operation is in progress
java.nio.channels.ClosedByInterruptException	If another thread interrupts the current thread while the write operation is in progress, thereby closing the channel and setting the current thread's interrupt status
java.io.IOException	If some other I/O error occurs
java.nio.channels.NotYetConnectedException	If this channel's socket is not connected