public boolean eval() throws BuildException 
{
                                  
        if (empty(host) && empty(url)) {
            throw new BuildException(ERROR_NO_HOSTNAME);
        }
        if (timeout <  0) {
            throw new BuildException(ERROR_BAD_TIMEOUT);
        }
        String target = host;
        if (!empty(url)) {
            if (!empty(host)) {
                throw new BuildException(ERROR_BOTH_TARGETS);
            }
            try {
                //get the host of a url
                URL realURL = new URL(url);
                target = realURL.getHost();
                if (empty(target)) {
                    throw new BuildException(ERROR_NO_HOST_IN_URL + url);
                }
            } catch (MalformedURLException e) {
                throw new BuildException(ERROR_BAD_URL + url, e);
            }
        }
        log("Probing host " + target, Project.MSG_VERBOSE);
        InetAddress address;
        try {
            address = InetAddress.getByName(target);
        } catch (UnknownHostException e1) {
            log(WARN_UNKNOWN_HOST + target);
            return false;
        }
        log("Host address = " + address.getHostAddress(),
                Project.MSG_VERBOSE);
        boolean reachable;
        //Java1.5: reachable = address.isReachable(timeout * 1000);
        Method reachableMethod = null;
        try {
            reachableMethod = InetAddress.class.getMethod(METHOD_NAME,
                    parameterTypes);
            Object[] params = new Object[1];
            params[0] = new Integer(timeout * SECOND);
            try {
                reachable = ((Boolean) reachableMethod.invoke(address, params))
                        .booleanValue();
            } catch (IllegalAccessException e) {
                //utterly implausible, but catered for anyway
                throw new BuildException("When calling " + reachableMethod);
            } catch (InvocationTargetException e) {
                //assume this is an IOexception about un readability
                Throwable nested = e.getTargetException();
                log(ERROR_ON_NETWORK + target + ": " + nested.toString());
                //any kind of fault: not reachable.
                reachable = false;
            }
        } catch (NoSuchMethodException e) {
            //java1.4 or earlier
            log("Not found: InetAddress." + METHOD_NAME, Project.MSG_VERBOSE);
            log(MSG_NO_REACHABLE_TEST);
            reachable = true;
        }
        log("host is" + (reachable ? "" : " not") + " reachable", Project.MSG_VERBOSE);
        return reachable;
}

Evaluate the condition.

 public  void setHost(String host) 
{
                    
        this.host = host;
}

Set the host to ping.

 public  void setTimeout(int timeout) 
{
        this.timeout = timeout;
}

Set the timeout for the reachability test in seconds.

 public  void setUrl(String url) 
{
        this.url = url;
}

Set the URL from which to extract the hostname.