File	Doc	Category	Size	Date	Package
DatagramPacket.java	API Doc	Java SE 5 API	11290	Fri Aug 26 14:57:08 BST 2005	java.net

DatagramPacket

• java.lang.Object

Fields Summary
byte[]	buf Perform class initialization
int	offset
int	length
int	bufLength
InetAddress	address
int	port

Constructors Summary
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. param buf buffer for holding the incoming datagram. param offset the offset for the buffer param length the number of bytes to read. since JDK1.2 setData(buf, offset, length); this.address = null; this.port = -1;
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. param buf buffer for holding the incoming datagram. param length the number of bytes to read. this (buf, 0, length);
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. param buf the packet data. param offset the packet data offset. param length the packet data length. param address the destination address. param port the destination port number. see java.net.InetAddress since JDK1.2 setData(buf, offset, length); setAddress(address); setPort(port);
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. param buf the packet data. param offset the packet data offset. param length the packet data length. param address the destination socket address. throws IllegalArgumentException if address type is not supported see java.net.InetAddress since 1.4 setData(buf, offset, length); setSocketAddress(address);
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. param buf the packet data. param length the packet length. param address the destination address. param port the destination port number. see java.net.InetAddress this(buf, 0, length, address, port);
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. param buf the packet data. param length the packet length. param address the destination address. throws IllegalArgumentException if address type is not supported since 1.4 see java.net.InetAddress this(buf, 0, length, address);

Methods Summary
public synchronized java.net.InetAddress	getAddress() Returns the IP address of the machine to which this datagram is being sent or from which the datagram was received. return the IP address of the machine to which this datagram is being sent or from which the datagram was received. see java.net.InetAddress see #setAddress(java.net.InetAddress) return address;
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. return the buffer used to receive or send data see #setData(byte[], int, int) return buf;
public synchronized int	getLength() Returns the length of the data to be sent or the length of the data received. return the length of the data to be sent or the length of the data received. see #setLength(int) return length;
public synchronized int	getOffset() Returns the offset of the data to be sent or the offset of the data received. return the offset of the data to be sent or the offset of the data received. since JDK1.2 return offset;
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. return the port number on the remote host to which this datagram is being sent or from which the datagram was received. see #setPort(int) return port;
public synchronized java.net.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. return the SocketAddress since 1.4 see #setSocketAddress return new InetSocketAddress(getAddress(), getPort());
private static native void	init() Perform class load-time initializations.
public synchronized void	setAddress(java.net.InetAddress iaddr) Sets the IP address of the machine to which this datagram is being sent. param iaddr the InetAddress since JDK1.1 see #getAddress() address = iaddr;
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. param buf the buffer to set for this packet param offset the offset into the data param length the length of the data and/or the length of the buffer used to receive data exception NullPointerException if the argument is null see #getData see #getOffset see #getLength since JDK1.2 /* this will check to see if buf is null */ if (length < 0 || offset < 0 || ((length + offset) > buf.length)) { throw new IllegalArgumentException("illegal length or offset"); } this.buf = buf; this.length = length; this.bufLength = length; this.offset = offset;
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. param buf the buffer to set for this packet. exception NullPointerException if the argument is null. see #getLength see #getData since JDK1.1 if (buf == null) { throw new NullPointerException("null packet buffer"); } this.buf = buf; this.offset = 0; this.length = buf.length; this.bufLength = buf.length;
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. param length the length to set for this packet. exception IllegalArgumentException if the length is negative of if the length is greater than the packet's data buffer length. see #getLength see #setData since JDK1.1 if ((length + offset) > buf.length || length < 0) { throw new IllegalArgumentException("illegal length"); } this.length = length; this.bufLength = this.length;
public synchronized void	setPort(int iport) Sets the port number on the remote host to which this datagram is being sent. param iport the port number since JDK1.1 see #getPort() if (iport < 0 || iport > 0xFFFF) { throw new IllegalArgumentException("Port out of range:"+ iport); } port = iport;
public synchronized void	setSocketAddress(java.net.SocketAddress address) Sets the SocketAddress (usually IP address + port number) of the remote host to which this datagram is being sent. param address the SocketAddress throws IllegalArgumentException if address is null or is a SocketAddress subclass not supported by this socket since 1.4 see #getSocketAddress if (address == null || !(address instanceof InetSocketAddress)) throw new IllegalArgumentException("unsupported address type"); InetSocketAddress addr = (InetSocketAddress) address; setAddress(addr.getAddress()); setPort(addr.getPort());