Question:
I would like to create a very simple applet that pings anIP address and returns a message stating whether that IP is alive. Icouldn’t find any straightforward answers to my problem in thejava.netpackage. How can I create a program with Java that performs this task?

Answer:
I created a little client program that opens a connection to the echoserver (always port 7) of a given host (using the domain name insteadof the IP address, hope that’s okay), sends the string “Hello,” readsthe response, then compares it with the string sent:

import java.io.*;import java.net.*;class Ping {   public static void main(String args[]) {      try {         Socket t = new Socket(args[0], 7);         DataInputStream is = new DataInputStream(t.getInputStream());         PrintStream os = new PrintStream(t.getOutputStream());         os.println(“Hello”);         String str = is.readLine();         if (str.equals(“Hello”))           System.out.println(“Alive :-)”) ;         else            System.out.println(“Dead :-(“);         t.close();      }      catch (IOException e) {System.out.println(“Error: ” + e);}   }}