Module java.base
Package java.net

Class DatagramPacket

java.lang.Object
java.net.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.

Unless otherwise specified, passing a null argument causes a NullPointerException to be thrown.

Methods and constructors of DatagramPacket accept parameters of type SocketAddress. DatagramPacket supports InetSocketAddress, and may support additional SocketAddress sub-types.

Since:
1.0

  • Constructor Summary

    Constructors
    Constructor
    Description
    DatagramPacket​(byte[] buf, int length)
    Constructs a DatagramPacket for receiving packets of length length.
    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 offset, int length, InetAddress address, int port)
    Constructs a datagram packet for sending packets of length length with offset offset to 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 offset to 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.

  • Method Summary

    Modifier and Type
    Method
    Description
    InetAddress
    getAddress()
    Returns the IP address of the machine to which this datagram is being sent or from which the datagram was received, or null if not set.
    byte[]
    getData()
    Returns the data buffer.
    int
    getLength()
    Returns the length of the data to be sent or the length of the data received.
    int
    getOffset()
    Returns the offset of the data to be sent or the offset of the data received.
    int
    getPort()
    Returns the port number on the remote host to which this datagram is being sent or from which the datagram was received, or 0 if not set.
    SocketAddress
    getSocketAddress()
    Returns the SocketAddress (usually IP address + port number) of the remote host that this packet is being sent to or is coming from.
    void
    setAddress​(InetAddress iaddr)
    Sets the IP address of the machine to which this datagram is being sent.
    void
    setData​(byte[] buf)
    Set the data buffer for this packet.
    void
    setData​(byte[] buf, int offset, int length)
    Set the data buffer for this packet.
    void
    setLength​(int length)
    Set the length for this packet.
    void
    setPort​(int iport)
    Sets the port number on the remote host to which this datagram is being sent.
    void
    setSocketAddress​(SocketAddress address)
    Sets the SocketAddress (usually IP address + port number) of the remote host to which this datagram is being sent.

    Methods declared in class java.lang.Object

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

  • Constructor Details

    • DatagramPacket

      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.
      Throws:
      IllegalArgumentException - if the length or offset is negative, or if the length plus the offset is greater than the length of the packet's given buffer.
      Since:
      1.2

    • DatagramPacket

      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.
      Throws:
      IllegalArgumentException - if the length is negative or if the length is greater than the length of the packet's given buffer.

    • DatagramPacket

      public DatagramPacket​(byte[] buf, int offset, int length, InetAddress address, int port)
      Constructs a datagram packet for sending packets of length length with offset offset 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.
      offset - the packet data offset.
      length - the packet data length.
      address - the destination address, or null.
      port - the destination port number.
      Throws:
      IllegalArgumentException - if the length or offset is negative, or if the length plus the offset is greater than the length of the packet's given buffer, or if the port is out of range.
      Since:
      1.2
      See Also:
      InetAddress

    • DatagramPacket

      public DatagramPacket​(byte[] buf, int offset, int length, SocketAddress address)
      Constructs a datagram packet for sending packets of length length with offset offset 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.
      offset - the packet data offset.
      length - the packet data length.
      address - the destination socket address.
      Throws:
      IllegalArgumentException - if address is null or its type is not supported, or if the length or offset is negative, or if the length plus the offset is greater than the length of the packet's given buffer.
      Since:
      1.4
      See Also:
      InetAddress

    • DatagramPacket

      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, or null.
      port - the destination port number.
      Throws:
      IllegalArgumentException - if the length is negative, or if the length is greater than the length of the packet's given buffer, or if the port is out of range.
      See Also:
      InetAddress

    • DatagramPacket

      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 is null or its type is not supported, or if the length is negative, or if the length is greater than the length of the packet's given buffer, or if the port is out of range.
      Since:
      1.4
      See Also:
      InetAddress

  • Method Details

    • getAddress

      public InetAddress getAddress()
      Returns the IP address of the machine to which this datagram is being sent or from which the datagram was received, or null if not set.
      Returns:
      the IP address of the machine to which this datagram is being sent or from which the datagram was received.
      See Also:
      InetAddress, setAddress(java.net.InetAddress)

    • getPort

      public int getPort()
      Returns the port number on the remote host to which this datagram is being sent or from which the datagram was received, or 0 if not set.
      Returns:
      the port number on the remote host to which this datagram is being sent or from which the datagram was received.
      See Also:
      setPort(int)

    • getData

      public 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
      See Also:
      setData(byte[], int, int)

    • getOffset

      public 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.
      Since:
      1.2

    • getLength

      public 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:
      setLength(int)

    • setData

      public 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:
      IllegalArgumentException - if the length or offset is negative, or if the length plus the offset is greater than the length of the packet's given buffer.
      Since:
      1.2
      See Also:
      getData(), getOffset(), getLength()

    • setAddress

      public void setAddress​(InetAddress iaddr)
      Sets the IP address of the machine to which this datagram is being sent.
      Parameters:
      iaddr - the InetAddress, or null.
      Since:
      1.1
      See Also:
      getAddress()

    • setPort

      public void setPort​(int iport)
      Sets the port number on the remote host to which this datagram is being sent.
      Parameters:
      iport - the port number
      Throws:
      IllegalArgumentException - if the port is out of range
      Since:
      1.1
      See Also:
      getPort()

    • setSocketAddress

      public 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.
      Since:
      1.4
      See Also:
      getSocketAddress()

    • getSocketAddress

      public SocketAddress getSocketAddress()
      Returns 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
      Since:
      1.4
      See Also:
      setSocketAddress(java.net.SocketAddress)

    • setData

      public 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.
      Since:
      1.1
      See Also:
      getLength(), getData()

    • setLength

      public 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, or if the length plus the offset is greater than the length of the packet's data buffer.
      Since:
      1.1
      See Also:
      getLength(), setData(byte[], int, int)