UDP - Java Network Programming - page 430

public void halt () {
this . stopped = true ;
}
@Override
public void run () {
try {
BufferedReader userInput
= new BufferedReader ( new InputStreamReader ( System . in ));
while ( true ) {
if ( stopped ) return ;
String theLine = userInput . readLine ();
if ( theLine . equals ( "." )) break ;
byte [] data = theLine . getBytes ( "UTF-8" );
DatagramPacket output
= new DatagramPacket ( data , data . length , server , port );
socket . send ( output );
Thread . yield ();
}
} catch ( IOException ex ) {
System . err . println ( ex );
}
}
}
The ReceiverThread class shown in Example 12-14 waits for datagrams to arrive from
the network. When a datagram is received, it is converted to a String and printed on
System.out for display to the user. A more advanced echo client could include an option
to send the output elsewhere.
This class has two fields. The more important is the DatagramSocket , theSocket , which
must be the same DatagramSocket used by the SenderThread . Data arrives on the port
used by that DatagramSocket ; any other DatagramSocket would not be allowed to con‐
nect to the same port. The second field, stopped , is a boolean used to halt this thread
without invoking the deprecated stop() method.
The run() method is an infinite loop that uses socket 's receive() method to wait for
incoming datagrams. When an incoming datagram appears, it is converted into a String
with the same length as the incoming data and printed on System.out . As in the input
thread, this thread then yields to give other threads an opportunity to execute.
Example 12-14. The ReceiverThread class
import java.io.* ;
import java.net.* ;
class ReceiverThread extends Thread {
private DatagramSocket socket ;