how do i write to a file i a udp stream?

//file named 0003388f.txt
File f= new File ("LogFile0003388f.txt");
// create Fileoutputstream
FileOutputStream fos= new FileOutputStream(f);
BufferedOutputStream bos = new BufferedOutputStream(fos);
// printwriter
PrintWriter pw = new PrintWriter(bos);

try
{
while(true)
{
// READ INTO THE DATAGRAM FROM THE SOCKET HERE
s.receive(p);
// finally extract the data received from the datagram and print it
// method .getData() returns a byte array
buf = p.getData();
len = p.getLength();
str = new String(buf,0,len);
System.out.println("LogReceiver: Got < "+str+" >");
pw.println(str);

if(str.equals("END"))
{
System.out.println("LogReceiver: Finished.");
System.exit(1);
}

}
}

catch (Exception e)
{
System.out.println("LogReceiver: Could not read from socket");
System.exit(1);
}