Java MulticastSocket setSoTimeout freezes program

Question

I am trying to use multicastsockets in a program of mine. Today, I'm not sure what changed, but my program (which hasn't changed and was working fine before) started freezing on random occasion when the setSoTimeout(int) method was called. It's not consistently, the method may be called a few times before this happens. Any clues as to what this is?

Code:

private String[] getPlayerInfo() {
    sendMessageToPlayers("count", 500);
    String[] temp = new String[4];
    while (true) {
        try {
            byte[] buffer = new byte[1000];
            DatagramPacket datagram = new DatagramPacket(buffer, buffer.length);
            cSocket.receive(datagram);
            String message = new String(datagram.getData());
            if (message.contains("received")) {
                message.substring(message.indexOf("received") - 1, 1);
                int playerNum = Integer.parseInt(message.substring(message.indexOf("received") - 1, 1));
                temp[playerNum] = message.substring(message.indexOf("received") + "received ".length());
            }
        } catch (IOException e) {
            try {
                cSocket.setSoTimeout(100000);
            } catch (SocketException e1) {
                break;
            }
            break;
        }
    }
    return temp;
}

public void sendMessageToPlayers(String message, int timeout) {
    byte[] buf = (message).getBytes();
    DatagramPacket dg = new DatagramPacket(buf, buf.length, group, 6789);
    try {
        cSocket.send(dg);
        cSocket.setSoTimeout(timeout);
    } catch (IOException ex) {
        System.out.println(ex);
    }
}

Answer 1

The documentation of setSoTimeout is

Enable/disable SO_TIMEOUT with the specified timeout, in milliseconds. With this option set to a non-zero timeout, a read() call on the InputStream associated with this Socket will block for only this amount of time. If the timeout expires, a java.net.SocketTimeoutException is raised, though the Socket is still valid. The option must be enabled prior to entering the blocking operation to have effect. The timeout must be > 0. A timeout of zero is interpreted as an infinite timeout.

And SO_TIMEOUT

Set a timeout on blocking Socket operations:

• ServerSocket.accept()
• SocketInputStream.read()
• DatagramSocket.receive()

The option must be set prior to entering a blocking operation to take effect. If the timeout expires and the operation would continue to block, java.io.InterruptedIOException is raised. The Socket is not closed in this case.

I don't understand the usage you made of it.