sockets - How To create the packet and send using java? -

hi getting data gps device, want send response gps device creating packet packet this.

no. field   type    length  description 1   smark    char   6   flag of message (\r\n*kw\0) 2   packetle short  2   message length 3   cmd  short  2   0x8200 4   cerrorcodechar  1   0x00ok, 0x01invalid deviceid 5   send     char   2   message end "\r\n" 

i want crete packet using code.

inetaddress ipaddress = receivepacket.getaddress();               string sendstring = "polo";               senddata = sendstring.getbytes();               datagrampacket sendpacket = new datagrampacket(senddata, senddata.length, ipaddress, port);               serversocket.send(sendpacket); 

i trying this.

 bytearrayoutputstream bytearrypacket = new bytearrayoutputstream();         dataoutputstream dateoutputpacket = new dataoutputstream(bytearrypacket);         dateoutputpacket.writechars("\r\n*kw\0");         dateoutputpacket.writeshort(15);         dateoutputpacket.writeshort(82);         dateoutputpacket.writechar('1');         dateoutputpacket.writechars("\r\n");         dateoutputpacket.flush();          byte[] result = bytearrypacket.tobytearray(); 

updated:

   bytearrayoutputstream bytearrypacket = new bytearrayoutputstream();     dataoutputstream dateoutputpacket = new dataoutputstream(bytearrypacket);     dateoutputpacket.writebytes("\r\n*kw\0");     dateoutputpacket.writeshort(15);     dateoutputpacket.writeshort(82);     dateoutputpacket.writebyte(1);     dateoutputpacket.writebytes("\r\n");     dateoutputpacket.flush();     byte[] result = bytearrypacket.tobytearray(); 

updated 2:

try {                         bytearrayoutputstream bytearrypacket = new bytearrayoutputstream();                         dataoutputstream dateoutputpacket = new dataoutputstream(bytearrypacket);                         dateoutputpacket.writebytes("\r\n*kw\0");                         dateoutputpacket.writeshort(15);                         dateoutputpacket.writeshort(82);                         dateoutputpacket.writebyte(1);                         dateoutputpacket.writebytes("\r\n");                         dateoutputpacket.flush();                         byte[] result = bytearrypacket.tobytearray();                         datagrampacket responsepacket = new datagrampacket(result, result.length, packet.getaddress(), packet.getport());                         dsocket.send(responsepacket);                     } catch (ioexception ex) {                         ex.printstacktrace();                     } catch (securityexception se) {                         se.printstacktrace();                     } catch (illegalblockingmodeexception il) {                         il.printstacktrace();                     } catch (illegalargumentexception ilg) {                         ilg.printstacktrace();                     } 

create dataoutputstream around bytearrayoutputstream; use various methods write data; bytes bytearrayoutputstream , wrap datagrampacket around that.