运行时什么也没有产生

package java_13DOMtest;

import java.io.IOException;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;

import org.xml.sax.SAXException;

public class DomTest {

public static void main(String[] args) {

DocumentBuilderFactory dbf=DocumentBuilderFactory.newInstance();

try {

DocumentBuilder db=dbf.newDocumentBuilder();

Document document =db.parse("books.xml");

}

catch (SAXException | IOException e) {

e.printStackTrace();}

catch (ParserConfigurationException e) {

e.printStackTrace();

}

}

}