DouKaku?

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.StringReader;
import java.net.URL;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Node;
import org.xml.sax.InputSource;

public class GetLastBuildDate {
    public static void main(String[] args) throws Exception {
         URL url = new URL("http://ja.doukaku.org/feeds/comments/");
         // 題意に沿ったもの
         BufferedReader br = new BufferedReader(new InputStreamReader(url.openStream(), "UTF-8"));
         StringBuffer buf = new StringBuffer();
         for (String s = br.readLine(); s != null; s = br.readLine()) {
             buf.append(s).append("\n");
         }
         String data = buf.toString();  // dataにXMLを文字列として格納
         System.out.println(getLastBuildDate(data));
         // より「Javaらしい」方法
         InputSource in = new InputSource(url.openStream());     // XMLはInputSourceで
         System.out.println(getLastBuildDate(in));
    }
    public static String getLastBuildDate(String data) throws XPathExpressionException {
        return getLastBuildDate(new InputSource(new StringReader(data)));
    }
    public static String getLastBuildDate(InputSource in) throws XPathExpressionException {
        XPath xpath = XPathFactory.newInstance().newXPath();
        String path = "//lastBuildDate";
        Node node = (Node)xpath.evaluate(path, in, XPathConstants.NODE);
        return node.getTextContent();
    }
}