Package Summary Overview Summary

### class:DatagramChannel [NONE]
> All Implemented Interfaces: `Closeable`, `AutoCloseable`, `ByteChannel`, `Channel`, `GatheringByteChannel`, `InterruptibleChannel`, `MulticastChannel`, `NetworkChannel`, `ReadableByteChannel`, `ScatteringByteChannel`, `WritableByteChannel` public abstract class DatagramChannel extends AbstractSelectableChannel implements ByteChannel, ScatteringByteChannel, GatheringByteChannel, MulticastChannel 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. Since: 1.4

### constructor:DatagramChannel(java.nio.channels.spi.SelectorProvider) [NONE]
### DatagramChannel protected DatagramChannel (SelectorProvider provider) Initializes a new instance of this class. Parameters: `provider` - The provider that created this channel

### method:open() [NONE]
### open public static DatagramChannel open() throws IOException Opens a datagram channel. The new channel is created by invoking the `openDatagramChannel` method of the system-wide default `SelectorProvider` 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. Returns: A new datagram channel Throws: `IOException` - If an I/O error occurs See Also: java.net.preferIPv4Stack system property

### method:open(java.net.ProtocolFamily) [NONE]
### open public static DatagramChannel open (ProtocolFamily family) throws IOException 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 `SelectorProvider` object. The channel will not be connected. API Note: Unix domain sockets are not supported. Parameters: `family` - The protocol family Returns: A new datagram channel Throws: `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. `IOException` - If an I/O error occurs Since: 1.7 See Also: java.net.preferIPv4Stack system property

### method:validOps() [NONE]
### validOps public final int validOps() Returns an operation set identifying this channel's supported operations. Datagram channels support reading and writing, so this method returns `(``SelectionKey.OP_READ``|` `SelectionKey.OP_WRITE``)`. Specified by: `validOps` in class `SelectableChannel` Returns: The valid-operation set

### method:bind(java.net.SocketAddress) [NONE]
### bind public abstract DatagramChannel bind (SocketAddress local) throws IOException Description copied from interface: `NetworkChannel` 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. Specified by: `bind` in interface `NetworkChannel` Parameters: `local` - The address to bind the socket, or `null` to bind the socket to an automatically assigned socket address Returns: This channel Throws: `AlreadyBoundException` - If the socket is already bound `UnsupportedAddressTypeException` - If the type of the given address is not supported `ClosedChannelException` - If the channel is closed `IOException` - If some other I/O error occurs `SecurityException` - If a security manager has been installed and its `checkListen` method denies the operation Since: 1.7 See Also: `NetworkChannel.getLocalAddress()` ### setOption public abstract <T> DatagramChannel setOption (SocketOption<T> name, T value) throws IOException Description copied from interface: `NetworkChannel` Sets the value of a socket option. Specified by: `setOption` in interface `NetworkChannel` 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 a valid value for some socket options. Returns: This channel Throws: `UnsupportedOperationException` - If the socket option is not supported by this channel `IllegalArgumentException` - If the value is not a valid value for this socket option `ClosedChannelException` - If this channel is closed `IOException` - If an I/O error occurs Since: 1.7 See Also: `StandardSocketOptions`

### method:socket() [NONE]
### socket public abstract DatagramSocket socket() Retrieves a datagram socket associated with this channel. Returns: A datagram socket associated with this channel

### method:isConnected() [NONE]
### isConnected public abstract boolean isConnected() Tells whether or not this channel's socket is connected. Returns: `true` if, and only if, this channel's socket is `open` and connected

### method:connect(java.net.SocketAddress) [NONE]
### connect public abstract DatagramChannel connect (SocketAddress remote) throws IOException 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. Datagrams in the channel's socket receive buffer , which have not been received before invoking this method, may be discarded. The channel's socket remains connected until it is explicitly disconnected or until it is closed. This method performs exactly the same security checks as the `connect` method of the `DatagramSocket` class. That is, if a security manager has been installed then this method verifies that its `checkAccept` and `checkConnect` methods permit datagrams to be received from and sent to, respectively, the given remote address. Once connected, no further security checks are performed for datagrams received from, or sent to, the given remote address. Care should be taken to ensure that a connected datagram channel is not shared with untrusted code. This method may be invoked at any time. If another thread has already initiated a read or write operation upon this channel, then an invocation of this method will block until any such 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: `remote` - The remote address to which this channel is to be connected Returns: This datagram channel Throws: `AlreadyConnectedException` - If this channel is already connected `ClosedChannelException` - If this channel is closed `AsynchronousCloseException` - If another thread closes this channel while the connect operation is in progress `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 `UnresolvedAddressException` - If the given remote address is not fully resolved `UnsupportedAddressTypeException` - If the type of the given remote address is not supported `SecurityException` - If a security manager has been installed and it does not permit access to the given remote address, or if unbound, the security manager `checkListen` method denies the operation `IOException` - If some other I/O error occurs

### method:disconnect() [NONE]
### disconnect public abstract DatagramChannel disconnect() throws IOException 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. If another thread has already initiated a read or write operation upon this channel, then an invocation of this method will block until any such operation is complete. If this channel's socket is not connected, or if the channel is closed, then invoking this method has no effect. API Note: If this method throws an IOException, the channel's socket may be left in an unspecified state. It is strongly recommended that the channel be closed when disconnect fails. Returns: This datagram channel Throws: `IOException` - If some other I/O error occurs

### method:getRemoteAddress() [NONE]
### getRemoteAddress public abstract SocketAddress getRemoteAddress() throws IOException Returns the remote address to which this channel's socket is connected. Returns: The remote address; `null` if the channel's socket is not connected Throws: `ClosedChannelException` - If the channel is closed `IOException` - If an I/O error occurs Since: 1.7

### method:receive(java.nio.ByteBuffer) [NONE]
### receive public abstract SocketAddress receive (ByteBuffer dst) throws IOException 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 `DatagramSocket` 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. Datagrams that are not permitted by the security manager are silently discarded. 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` - The buffer into which the datagram is to be transferred Returns: The datagram's source address, or `null` if this channel is in non-blocking mode and no datagram was immediately available Throws: `IllegalArgumentException` - If the buffer is read-only `ClosedChannelException` - If this channel is closed `AsynchronousCloseException` - If another thread closes this channel while the read operation is in progress `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 `SecurityException` - If unbound, and a security manager has been installed and its `checkListen` method denies the operation `IOException` - If some other I/O error occurs

### method:send(java.nio.ByteBuffer,java.net.SocketAddress) [NONE]
### send public abstract int send (ByteBuffer src, SocketAddress target) throws IOException 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 `DatagramSocket` 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 `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` - The buffer containing the datagram to be sent `target` - The address to which the datagram is to be sent Returns: 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 Throws: `AlreadyConnectedException` - If this channel is connected to a different address from that specified by `target` `ClosedChannelException` - If this channel is closed `AsynchronousCloseException` - If another thread closes this channel while the read operation is in progress `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 `UnresolvedAddressException` - If the given remote address is not fully resolved `UnsupportedAddressTypeException` - If the type of the given remote address is not supported `SecurityException` - If a security manager has been installed and it does not permit datagrams to be sent to the given address, or if unbound, and the security manager's `checkListen` method denies the operation `IOException` - If some other I/O error occurs

### method:read(java.nio.ByteBuffer) [NONE]
### read public abstract int read (ByteBuffer dst) throws IOException 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. Specified by: `read` in interface `ReadableByteChannel` Parameters: `dst` - The buffer into which bytes are to be transferred Returns: The number of bytes read, possibly zero, or `-1` if the channel has reached end-of-stream Throws: `NotYetConnectedException` - If this channel's socket is not connected `ClosedChannelException` - If this channel is closed `AsynchronousCloseException` - If another thread closes this channel while the read operation is in progress `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 `IOException` - If some other I/O error occurs

### method:read(java.nio.ByteBuffer[],int,int) [NONE]
### read public abstract long read (ByteBuffer[] dsts, int offset, int length) throws IOException 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. Specified by: `read` in interface `ScatteringByteChannel` Parameters: `dsts` - The buffers into which bytes are to be transferred `offset` - 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` - The maximum number of buffers to be accessed; must be non-negative and no larger than `dsts.length` - `offset` Returns: The number of bytes read, possibly zero, or `-1` if the channel has reached end-of-stream Throws: `NotYetConnectedException` - If this channel's socket is not connected `ClosedChannelException` - If this channel is closed `AsynchronousCloseException` - If another thread closes this channel while the read operation is in progress `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 `IOException` - If some other I/O error occurs

### method:read(java.nio.ByteBuffer[]) [NONE]
### read public final long read (ByteBuffer[] dsts) throws IOException 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. Specified by: `read` in interface `ScatteringByteChannel` Parameters: `dsts` - The buffers into which bytes are to be transferred Returns: The number of bytes read, possibly zero, or `-1` if the channel has reached end-of-stream Throws: `NotYetConnectedException` - If this channel's socket is not connected `ClosedChannelException` - If this channel is closed `AsynchronousCloseException` - If another thread closes this channel while the read operation is in progress `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 `IOException` - If some other I/O error occurs

### method:write(java.nio.ByteBuffer) [NONE]
### write public abstract int write (ByteBuffer src) throws IOException 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. Specified by: `write` in interface `WritableByteChannel` Parameters: `src` - The buffer from which bytes are to be retrieved Returns: The number of bytes written, possibly zero Throws: `NotYetConnectedException` - If this channel's socket is not connected `ClosedChannelException` - If this channel is closed `AsynchronousCloseException` - If another thread closes this channel while the write operation is in progress `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 `IOException` - If some other I/O error occurs

### method:write(java.nio.ByteBuffer[],int,int) [NONE]
### write public abstract long write (ByteBuffer[] srcs, int offset, int length) throws IOException 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. Specified by: `write` in interface `GatheringByteChannel` Parameters: `srcs` - The buffers from which bytes are to be retrieved `offset` - 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` - The maximum number of buffers to be accessed; must be non-negative and no larger than `srcs.length` - `offset` Returns: 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 Throws: `NotYetConnectedException` - If this channel's socket is not connected `ClosedChannelException` - If this channel is closed `AsynchronousCloseException` - If another thread closes this channel while the write operation is in progress `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 `IOException` - If some other I/O error occurs

### method:write(java.nio.ByteBuffer[]) [NONE]
### write public final long write (ByteBuffer[] srcs) throws IOException 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. Specified by: `write` in interface `GatheringByteChannel` Parameters: `srcs` - The buffers from which bytes are to be retrieved Returns: 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 Throws: `NotYetConnectedException` - If this channel's socket is not connected `ClosedChannelException` - If this channel is closed `AsynchronousCloseException` - If another thread closes this channel while the write operation is in progress `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 `IOException` - If some other I/O error occurs

### method:getLocalAddress() [NONE]
### getLocalAddress public abstract SocketAddress getLocalAddress() throws IOException 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 `InetSocketAddress`. 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. Specified by: `getLocalAddress` in interface `NetworkChannel` Returns: 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 Throws: `ClosedChannelException` - If the channel is closed `IOException` - If an I/O error occurs