DatagramPacket

public final class DatagramPacket extends Object

This class represents a datagram packet.

Datagram packets are used to implement a connectionless packet delivery service. Each message is routed from one machine to another based solely on information contained within that packet. Multiple packets sent from one machine to another might be routed differently, and might arrive in any order. Packet delivery is not guaranteed.

Public Constructor Summary

DatagramPacket(byte[] buf, int offset, int length)
Constructs a DatagramPacket for receiving packets of length length, specifying an offset into the buffer.
DatagramPacket(byte[] buf, int length)
Constructs a DatagramPacket for receiving packets of length length.
DatagramPacket(byte[] buf, int offset, int length, InetAddress address, int port)
Constructs a datagram packet for sending packets of length length with offset ioffsetto the specified port number on the specified host.
DatagramPacket(byte[] buf, int offset, int length, SocketAddress address)
Constructs a datagram packet for sending packets of length length with offset ioffsetto the specified port number on the specified host.
DatagramPacket(byte[] buf, int length, InetAddress address, int port)
Constructs a datagram packet for sending packets of length length to the specified port number on the specified host.
DatagramPacket(byte[] buf, int length, SocketAddress address)
Constructs a datagram packet for sending packets of length length to the specified port number on the specified host.

Public Method Summary

synchronized InetAddress
getAddress()
Returns the IP address of the machine to which this datagram is being sent or from which the datagram was received.
synchronized byte[]
getData()
Returns the data buffer.
synchronized int
getLength()
Returns the length of the data to be sent or the length of the data received.
synchronized int
getOffset()
Returns the offset of the data to be sent or the offset of the data received.
synchronized int
getPort()
Returns the port number on the remote host to which this datagram is being sent or from which the datagram was received.
synchronized SocketAddress
getSocketAddress()
Gets the SocketAddress (usually IP address + port number) of the remote host that this packet is being sent to or is coming from.
synchronized void
setAddress(InetAddress iaddr)
Sets the IP address of the machine to which this datagram is being sent.
synchronized void
setData(byte[] buf, int offset, int length)
Set the data buffer for this packet.
synchronized void
setData(byte[] buf)
Set the data buffer for this packet.
synchronized void
setLength(int length)
Set the length for this packet.
synchronized void
setPort(int iport)
Sets the port number on the remote host to which this datagram is being sent.
synchronized void
setSocketAddress(SocketAddress address)
Sets the SocketAddress (usually IP address + port number) of the remote host to which this datagram is being sent.

Inherited Method Summary

Public Constructors

public DatagramPacket (byte[] buf, int offset, int length)

Constructs a DatagramPacket for receiving packets of length length, specifying an offset into the buffer.

The length argument must be less than or equal to buf.length.

Parameters
buf buffer for holding the incoming datagram.
offset the offset for the buffer
length the number of bytes to read.

public DatagramPacket (byte[] buf, int length)

Constructs a DatagramPacket for receiving packets of length length.

The length argument must be less than or equal to buf.length.

Parameters
buf buffer for holding the incoming datagram.
length the number of bytes to read.

public DatagramPacket (byte[] buf, int offset, int length, InetAddress address, int port)

Constructs a datagram packet for sending packets of length length with offset ioffsetto the specified port number on the specified host. The length argument must be less than or equal to buf.length.

Parameters
buf the packet data.
offset the packet data offset.
length the packet data length.
address the destination address.
port the destination port number.
See Also

public DatagramPacket (byte[] buf, int offset, int length, SocketAddress address)

Constructs a datagram packet for sending packets of length length with offset ioffsetto the specified port number on the specified host. The length argument must be less than or equal to buf.length.

Parameters
buf the packet data.
offset the packet data offset.
length the packet data length.
address the destination socket address.
Throws
IllegalArgumentException if address type is not supported
SocketException
See Also

public DatagramPacket (byte[] buf, int length, InetAddress address, int port)

Constructs a datagram packet for sending packets of length length to the specified port number on the specified host. The length argument must be less than or equal to buf.length.

Parameters
buf the packet data.
length the packet length.
address the destination address.
port the destination port number.
See Also

public DatagramPacket (byte[] buf, int length, SocketAddress address)

Constructs a datagram packet for sending packets of length length to the specified port number on the specified host. The length argument must be less than or equal to buf.length.

Parameters
buf the packet data.
length the packet length.
address the destination address.
Throws
IllegalArgumentException if address type is not supported
SocketException
See Also

Public Methods

public synchronized InetAddress getAddress ()

Returns the IP address of the machine to which this datagram is being sent or from which the datagram was received.

Returns
  • the IP address of the machine to which this datagram is being sent or from which the datagram was received.

public synchronized byte[] getData ()

Returns the data buffer. The data received or the data to be sent starts from the offset in the buffer, and runs for length long.

Returns
  • the buffer used to receive or send data

public synchronized int getLength ()

Returns the length of the data to be sent or the length of the data received.

Returns
  • the length of the data to be sent or the length of the data received.
See Also

public synchronized int getOffset ()

Returns the offset of the data to be sent or the offset of the data received.

Returns
  • the offset of the data to be sent or the offset of the data received.

public synchronized int getPort ()

Returns the port number on the remote host to which this datagram is being sent or from which the datagram was received.

Returns
  • the port number on the remote host to which this datagram is being sent or from which the datagram was received.
See Also

public synchronized SocketAddress getSocketAddress ()

Gets the SocketAddress (usually IP address + port number) of the remote host that this packet is being sent to or is coming from.

Returns
  • the SocketAddress

public synchronized void setAddress (InetAddress iaddr)

Sets the IP address of the machine to which this datagram is being sent.

Parameters
iaddr the InetAddress
See Also

public synchronized void setData (byte[] buf, int offset, int length)

Set the data buffer for this packet. This sets the data, length and offset of the packet.

Parameters
buf the buffer to set for this packet
offset the offset into the data
length the length of the data and/or the length of the buffer used to receive data
Throws
NullPointerException if the argument is null

public synchronized void setData (byte[] buf)

Set the data buffer for this packet. With the offset of this DatagramPacket set to 0, and the length set to the length of buf.

Parameters
buf the buffer to set for this packet.
Throws
NullPointerException if the argument is null.

public synchronized void setLength (int length)

Set the length for this packet. The length of the packet is the number of bytes from the packet's data buffer that will be sent, or the number of bytes of the packet's data buffer that will be used for receiving data. The length must be lesser or equal to the offset plus the length of the packet's buffer.

Parameters
length the length to set for this packet.
Throws
IllegalArgumentException if the length is negative of if the length is greater than the packet's data buffer length.

public synchronized void setPort (int iport)

Sets the port number on the remote host to which this datagram is being sent.

Parameters
iport the port number
See Also

public synchronized void setSocketAddress (SocketAddress address)

Sets the SocketAddress (usually IP address + port number) of the remote host to which this datagram is being sent.

Parameters
address the SocketAddress
Throws
IllegalArgumentException if address is null or is a SocketAddress subclass not supported by this socket