public void changeNickname(String[] strs){
	    //input string format (everything inside <> is variable):
	    //<username>(NAME_CHANGE): <newnickname>

	    //split input to get user's data
	    String[] strings1 = strs[0].split("\\(");
	    String[] strings2 = strs[0].split(": ");
	    String username = strings1[0];
	    String oldNickname = "";
	    String newNickname = strings2[1];

	    //search the server's client list for the one that is changing its nickname
	    for(Client c : clients){
		if(c.getUser().getName().equals(username))
		    {
			oldNickname = c.getUser().getNickname();

			//update server's users and send message to client to change its nickname 
			if (c.sendMsg(newNickname + "&1007") == 0){
			c.getUser().setNickname(newNickname);
			//display messages on the server and client about the nickname change
			controller.displayMsg(serverMsgPrefix + username + "'s nickname has been changed from " + oldNickname + " to " + newNickname);
			c.sendMsg("Your nickname has been changed from " + oldNickname + " to " + newNickname + "&1001");
            }
			else
			c.sendMsg("Nickname change failed" + "&1001");
			break;
		    }
	    }

	    //notify all other contacts that the user has changed their nickname
	    for(Client c : clients)
		if(!c.getUser().getName().equals(username))
		    c.sendMsg(oldNickname + ":" + newNickname + "&1006");

	    //update the user's new nickname in the users
	    for(User u : users)
		if(u.getName().equals(username))
		    u.setNickname(newNickname);
	}