This Java tip shows how to scan your computer for ports in use.

Java Code:
import java.net.ServerSocket;

public class LocalScan {
  public static void main(String[] args) {
    for (int i = 1; i < 1023; i++) {
      testPort(i);
    }
    System.out.println("Completed");
  }

  private static void testPort(int i) {
    try {
      ServerSocket sock = new ServerSocket(i);
    } catch (java.io.IOException e) {
      System.out.println("Port " + i + " in use.");
    }
  }
}