How to find a free port — Java

import java.io.IOException;
import java.net.ServerSocket;

public static int findAFreePort() {
        try {
            ServerSocket server = new ServerSocket(0);
            int port = server.getLocalPort();
            server.close();
            return port;
        } catch (IOException ex) {
            throw new RuntimeException("Failed to find a free port.", ex);
        }
    }

I am using this post a documentation for myself. Nothing much say, code block is self explanatory.