This program calls send/receive after trying to connect to a non-existing DatagramSocket, it times out after 5 seconds without throwing a PortUnreachableException.

Apple JDK 6 throws a PortUnreachableException immediately.

import java.net.*;

public class A1 {

    public static void main(String[] args) throws Exception {
        byte[] data = "hello".getBytes();
        InetAddress iaddr = InetAddress.getByName("localhost");
        DatagramSocket dgSocket = new DatagramSocket();
        dgSocket.setSoTimeout(5000);
        dgSocket.connect(iaddr, 8080);
        DatagramPacket dgPacketOut = new DatagramPacket(data, data.length,
                                                        iaddr, 8080);
        dgSocket.send(dgPacketOut);
        byte ibuf[] = new byte[1024];
        DatagramPacket dgPacketIn = new DatagramPacket(ibuf, ibuf.length);
        dgSocket.receive(dgPacketIn);
    }
}