test.java

import java.util.Scanner;

public class test
{
    public static void main(String[] args)
    {
        String input;
        System.out.println("Hello, welcome to the forum.  Input your post");

        Scanner k = new Scanner(System.in);
        input = k.nextLine();

        input = input.replaceAll("([^A-Za-z])[dD][oO][gG]([^A-Za-z])","$1!@#$2");
        input = input.replaceAll("^[dD][oO][gG]([^A-Za-z])","!@#$1");
        input = input.replaceAll("([^A-Za-z])[dD][oO][gG]$","$1!@#");
        System.out.println("Your thread has been posted");
        System.out.println(input);
    }
}