Ping a server

From WikiJava

This example shows how to perform a pseudo ping in Java

the article

It's not possible to really "ping" a machine to check if it's alive or not (it's a long story, but to keep it short I will just say that the Socket class is not low-level enough for that operation). But we can emulate a ping by talking the "echo port". On a server, the echo port is always port 7. We write a string to that port and the server will echo the string.

pseudo ping

import java.io.*;
import java.net.*;
 
public class PseudoPing {
  public static void main(String args[]) {
    try {
      Socket t = new Socket(args[0], 7);
      DataInputStream dis = new DataInputStream(t.getInputStream());
      PrintStream ps = new PrintStream(t.getOutputStream());
      ps.println("Hello");
      String str = dis.readLine();
      if (str.equals("Hello"))
        System.out.println("Alive!") ;
      else
        System.out.println("Dead or echo port not responding");              
      t.close();
    }
    catch (IOException e) {
      e.printStackTrace();}
    }
  }
}

See Also

ping a server jdk1.5, Real's Java How To

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