We can check if a given port is free by trying to construct a ServerSocket with the port that needs to be checked:

import java.io.*;import java.net.*;public class CheckingIfPortIsFree{   public static void main(String args[])   {      CheckingIfPortIsFree checkingIfPortIsFree = new CheckingIfPortIsFree();      checkingIfPortIsFree.proceed();   }      private void proceed()   {      int portToBeChecked = 4567;      boolean isPortFree;            try {         ServerSocket serverSocket = new ServerSocket(portToBeChecked);         isPortFree = true;      }      catch (IOException ioe)      {        isPortFree = false;      }      System.out.println("isPortFree: " + isPortFree);   }}/*

Expected output:

[root@mypc]# java CheckingIfPortIsFreeisPortFree: true*/