java program to check whether a port is being used or not


Levels of difficulty: / perform operation:

java program

import java.net.*;
import java.io.*;
public class Main {
	public static void main(String[] args) {
		Socket Skt;
		String host = "localhost";
		if (args.length gt;0) {
			host = args[0];
		}
		for (int i = 0; i < 1024; i++) {
			try {
			     System.out.println("Looking for "+ i);
		             Skt = new Socket(host, i);
			     System.out.println("There is a server on port "+ i + " of " + host);
			}
			catch (UnknownHostException e) {
				System.out.println("Exception occured"+ e);
				break;
			}
			catch (IOException e) {
			}
		}
	}
}


Output

Looking for 0
Looking for 1
Looking for 2
Looking for 3
Looking for 4. . .